Mobile Ad hoc Networking (MANET) T. Clausen Internet-Draft LIX, Ecole Polytechnique Intended status: Standards Track C. Dearlove Expires: April 16, 2012 BAE Systems ATC P. Jacquet Project Hipercom, INRIA October 14, 2011 The Optimized Link State Routing Protocol version 2 draft-ietf-manet-olsrv2-13 Abstract This document describes version 2 of the Optimized Link State Routing (OLSRv2) protocol for Mobile Ad hoc NETworks (MANETs). Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on April 16, 2012. Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Clausen, et al. Expires April 16, 2012 [Page 1] Internet-Draft OLSRv2 October 2011 This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 6 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 7 3. Applicability Statement . . . . . . . . . . . . . . . . . . . 9 4. Protocol Overview and Functioning . . . . . . . . . . . . . . 10 4.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 10 4.2. Routers and Interfaces . . . . . . . . . . . . . . . . . 13 4.3. Information Base Overview . . . . . . . . . . . . . . . . 14 4.3.1. Local Information Base . . . . . . . . . . . . . . . 14 4.3.2. Interface Information Bases . . . . . . . . . . . . . 14 4.3.3. Neighbor Information Base . . . . . . . . . . . . . . 14 4.3.4. Topology Information Base . . . . . . . . . . . . . . 15 4.3.5. Received Message Information Base . . . . . . . . . . 16 4.4. Signaling Overview . . . . . . . . . . . . . . . . . . . 16 4.5. Link Metrics . . . . . . . . . . . . . . . . . . . . . . 17 4.6. Routing Set Use . . . . . . . . . . . . . . . . . . . . . 18 5. Protocol Parameters and Constants . . . . . . . . . . . . . . 19 5.1. Protocol and Port Numbers . . . . . . . . . . . . . . . . 19 5.2. Multicast Address . . . . . . . . . . . . . . . . . . . . 19 5.3. Interface Parameters . . . . . . . . . . . . . . . . . . 19 5.3.1. Received Message Validity Time . . . . . . . . . . . 20 5.4. Router Parameters . . . . . . . . . . . . . . . . . . . . 20 5.4.1. Local History Times . . . . . . . . . . . . . . . . . 20 5.4.2. Link Metric Parameters . . . . . . . . . . . . . . . 20 5.4.3. Message Intervals . . . . . . . . . . . . . . . . . . 20 5.4.4. Advertised Information Validity Times . . . . . . . . 21 5.4.5. Processing and Forwarding Validity Times . . . . . . 22 5.4.6. Jitter . . . . . . . . . . . . . . . . . . . . . . . 22 5.4.7. Hop Limit . . . . . . . . . . . . . . . . . . . . . . 23 5.4.8. Willingness . . . . . . . . . . . . . . . . . . . . . 23 5.5. Parameter Change Constraints . . . . . . . . . . . . . . 24 5.6. Constants . . . . . . . . . . . . . . . . . . . . . . . . 26 5.6.1. Link Metric Constants . . . . . . . . . . . . . . . . 26 5.6.2. Willingness Constants . . . . . . . . . . . . . . . . 26 6. Link Metric Values . . . . . . . . . . . . . . . . . . . . . 27 Clausen, et al. Expires April 16, 2012 [Page 2] Internet-Draft OLSRv2 October 2011 6.1. Link Metric Representation . . . . . . . . . . . . . . . 27 6.2. Link Metric Compressed Form . . . . . . . . . . . . . . . 27 7. Local Information Base . . . . . . . . . . . . . . . . . . . 28 7.1. Originator Set . . . . . . . . . . . . . . . . . . . . . 28 7.2. Local Attached Network Set . . . . . . . . . . . . . . . 29 8. Interface Information Base . . . . . . . . . . . . . . . . . 30 8.1. Link Set . . . . . . . . . . . . . . . . . . . . . . . . 30 8.2. 2-Hop Set . . . . . . . . . . . . . . . . . . . . . . . . 30 9. Neighbor Information Base . . . . . . . . . . . . . . . . . . 31 10. Topology Information Base . . . . . . . . . . . . . . . . . . 32 10.1. Advertising Remote Router Set . . . . . . . . . . . . . . 32 10.2. Router Topology Set . . . . . . . . . . . . . . . . . . . 33 10.3. Routable Address Topology Set . . . . . . . . . . . . . . 34 10.4. Attached Network Set . . . . . . . . . . . . . . . . . . 34 10.5. Routing Set . . . . . . . . . . . . . . . . . . . . . . . 35 11. Received Message Information Base . . . . . . . . . . . . . . 36 11.1. Received Set . . . . . . . . . . . . . . . . . . . . . . 36 11.2. Processed Set . . . . . . . . . . . . . . . . . . . . . . 36 11.3. Forwarded Set . . . . . . . . . . . . . . . . . . . . . . 37 12. Information Base Properties . . . . . . . . . . . . . . . . . 37 13. Packets and Messages . . . . . . . . . . . . . . . . . . . . 39 13.1. Messages . . . . . . . . . . . . . . . . . . . . . . . . 39 13.2. Packets . . . . . . . . . . . . . . . . . . . . . . . . . 39 13.3. TLVs . . . . . . . . . . . . . . . . . . . . . . . . . . 40 13.3.1. Message TLVs . . . . . . . . . . . . . . . . . . . . 40 13.3.2. Address Block TLVs . . . . . . . . . . . . . . . . . 40 14. Message Processing and Forwarding . . . . . . . . . . . . . . 42 14.1. Actions when Receiving a Message . . . . . . . . . . . . 43 14.2. Message Considered for Processing . . . . . . . . . . . . 44 14.3. Message Considered for Forwarding . . . . . . . . . . . . 45 15. HELLO Messages . . . . . . . . . . . . . . . . . . . . . . . 46 15.1. HELLO Message Generation . . . . . . . . . . . . . . . . 47 15.2. HELLO Message Transmission . . . . . . . . . . . . . . . 48 15.3. HELLO Message Processing . . . . . . . . . . . . . . . . 49 15.3.1. HELLO Message Discarding . . . . . . . . . . . . . . 49 15.3.2. HELLO Message Usage . . . . . . . . . . . . . . . . . 50 16. TC Messages . . . . . . . . . . . . . . . . . . . . . . . . . 53 16.1. TC Message Generation . . . . . . . . . . . . . . . . . . 53 16.2. TC Message Transmission . . . . . . . . . . . . . . . . . 55 16.3. TC Message Processing . . . . . . . . . . . . . . . . . . 56 16.3.1. Invalid Message . . . . . . . . . . . . . . . . . . . 56 16.3.2. TC Message Processing Definitions . . . . . . . . . . 57 16.3.3. Initial TC Message Processing . . . . . . . . . . . . 58 16.3.4. Completing TC Message Processing . . . . . . . . . . 61 17. Information Base Changes . . . . . . . . . . . . . . . . . . 62 17.1. Originator Address Changes . . . . . . . . . . . . . . . 62 17.2. Link State Changes . . . . . . . . . . . . . . . . . . . 63 17.3. Neighbor State Changes . . . . . . . . . . . . . . . . . 63 Clausen, et al. Expires April 16, 2012 [Page 3] Internet-Draft OLSRv2 October 2011 17.4. Advertised Neighbor Changes . . . . . . . . . . . . . . . 64 17.5. Advertising Remote Router Tuple Expires . . . . . . . . . 64 17.6. Neighborhood Changes and MPR Updates . . . . . . . . . . 65 17.7. Routing Set Updates . . . . . . . . . . . . . . . . . . . 66 18. Selecting MPRs . . . . . . . . . . . . . . . . . . . . . . . 67 18.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 68 18.2. Neighbor Graph . . . . . . . . . . . . . . . . . . . . . 68 18.3. MPR Properties . . . . . . . . . . . . . . . . . . . . . 69 18.4. Flooding MPRs . . . . . . . . . . . . . . . . . . . . . . 70 18.5. Routing MPRs . . . . . . . . . . . . . . . . . . . . . . 72 18.6. Calculating MPRs . . . . . . . . . . . . . . . . . . . . 73 19. Routing Set Calculation . . . . . . . . . . . . . . . . . . . 73 19.1. Network Topology Graph . . . . . . . . . . . . . . . . . 74 19.2. Populating the Routing Set . . . . . . . . . . . . . . . 76 20. Proposed Values for Parameters . . . . . . . . . . . . . . . 77 20.1. Local History Time Parameters . . . . . . . . . . . . . . 77 20.2. Message Interval Parameters . . . . . . . . . . . . . . . 77 20.3. Advertised Information Validity Time Parameters . . . . . 77 20.4. Received Message Validity Time Parameters . . . . . . . . 77 20.5. Jitter Time Parameters . . . . . . . . . . . . . . . . . 78 20.6. Hop Limit Parameter . . . . . . . . . . . . . . . . . . . 78 20.7. Willingness Parameter . . . . . . . . . . . . . . . . . . 78 21. Sequence Numbers . . . . . . . . . . . . . . . . . . . . . . 78 22. Extensions . . . . . . . . . . . . . . . . . . . . . . . . . 79 23. Security Considerations . . . . . . . . . . . . . . . . . . . 79 23.1. Confidentiality . . . . . . . . . . . . . . . . . . . . . 79 23.2. Integrity . . . . . . . . . . . . . . . . . . . . . . . . 80 23.3. Interaction with External Routing Domains . . . . . . . . 81 24. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 82 24.1. Expert Review: Evaluation Guidelines . . . . . . . . . . 82 24.2. Message Types . . . . . . . . . . . . . . . . . . . . . . 82 24.3. Message-Type-Specific TLV Type Registries . . . . . . . . 82 24.4. Message TLV Types . . . . . . . . . . . . . . . . . . . . 83 24.5. Address Block TLV Types . . . . . . . . . . . . . . . . . 84 24.6. NBR_ADDR_TYPE and MPR Values . . . . . . . . . . . . . . 87 25. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 87 26. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 88 27. References . . . . . . . . . . . . . . . . . . . . . . . . . 88 27.1. Normative References . . . . . . . . . . . . . . . . . . 88 27.2. Informative References . . . . . . . . . . . . . . . . . 89 Appendix A. Example Algorithm for Calculating MPRs . . . . . . . 89 A.1. Additional Notation . . . . . . . . . . . . . . . . . . . 89 A.2. MPR Selection Algorithm . . . . . . . . . . . . . . . . . 90 Appendix B. Example Algorithm for Calculating the Routing Set . 91 B.1. Local Interfaces and Neighbors . . . . . . . . . . . . . 91 B.2. Add Neighbor Routers . . . . . . . . . . . . . . . . . . 92 B.3. Add Remote Routers . . . . . . . . . . . . . . . . . . . 92 B.4. Add Neighbor Addresses . . . . . . . . . . . . . . . . . 94 Clausen, et al. Expires April 16, 2012 [Page 4] Internet-Draft OLSRv2 October 2011 B.5. Add Remote Routable Addresses . . . . . . . . . . . . . . 94 B.6. Add Attached Networks . . . . . . . . . . . . . . . . . . 95 B.7. Add 2-Hop Neighbors . . . . . . . . . . . . . . . . . . . 95 Appendix C. TC Message Example . . . . . . . . . . . . . . . . . 96 Appendix D. Constraints . . . . . . . . . . . . . . . . . . . . 98 Appendix E. Flow and Congestion Control . . . . . . . . . . . . 103 Clausen, et al. Expires April 16, 2012 [Page 5] Internet-Draft OLSRv2 October 2011 1. Introduction The Optimized Link State Routing protocol version 2 (OLSRv2) is an update to OLSR (version 1) as published in [RFC3626]. Compared to [RFC3626], OLSRv2 retains the same basic mechanisms and algorithms, enhanced by the ability to use a link metric other than hop count in the selection of shortest routes. OLSRv2 also uses a more flexible and efficient signaling framework, and includes some simplification of the messages being exchanged. OLSRv2 is developed for mobile ad hoc networks (MANETs). It operates as a table driven, proactive protocol, i.e., it exchanges topology information with other routers in the network regularly. OLSRv2 is an optimization of the classical link state routing protocol. Its key concept is that of MultiPoint Relays (MPRs). Each router selects two sets of MPRs, each being a set of its neighbor routers that "cover" all of its symmetrically connected 2-hop neighbor routers. These two sets are of flooding MPRs and routing MPRs, and are used to achieve flooding reduction and topology reduction, respectively. Flooding reduction is achieved by control traffic being flooded through the network using hop by hop forwarding, but with a router only needing to forward control traffic that is first received directly from one of the routers that have selected it as a flooding MPR (its "flooding MPR selectors"). This mechanism, denoted "MPR flooding", provides an efficient mechanism for information distribution within the MANET by reducing the number of transmissions required. Topology reduction is achieved by assigning a special responsibility to routers selected as routing MPRs when declaring link state information. A sufficient requirement for OLSRv2 to provide shortest routes to all destinations is that routers declare link state information for their routing MPR selectors, if any. Routers that are not selected as routing MPRs need not send any link state information. Based on this reduced link state information, routing MPRs are used as intermediate routers in multi-hop routes. Thus the use of MPRs allows reduction of the number and the size of link state messages, and in the amount of link state information maintained in each router. When possible (in particular if using a hop count metric) the same routers may be picked as both flooding MPRs and routing MPRs. A router selects both routing and flooding MPRs from among its one hop neighbors connected by "symmetric", i.e., bidirectional, links. Therefore, selecting routes through routing MPRs avoids the problems associated with data packet transfer over unidirectional links (e.g., Clausen, et al. Expires April 16, 2012 [Page 6] Internet-Draft OLSRv2 October 2011 the problem of not getting link layer acknowledgments at each hop, for link layers employing this technique). OLSRv2 uses and extends the MANET NeighborHood Discovery Protocol (NHDP) defined in [RFC6130] and also uses the MANET generalized packet/message format [RFC5444] and the specifications in [RFC5497] and, optionally, [RFC5148]. These four other protocols and specifications were all originally created as part of OLSRv2, but have been specified separately for wider use. OLSRv2 makes no assumptions about the underlying link layer. OLSRv2, through its use of [RFC6130], may use link layer information and notifications when available and applicable. In addition OLSRv2 uses link metrics that may be derived from link layer or any other information. OLSRv2 does not specify the physical meaning of link metrics, but specifies a means by which new types of link metrics may be specified in the future, but used by OLSRv2 without modification. OLSRv2, as OLSR [RFC3626], inherits its concept of forwarding and relaying from HIPERLAN (a MAC layer protocol) which is standardized by ETSI [HIPERLAN], [HIPERLAN2]. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. All terms introduced in [RFC5444], including "packet", "Packet Header", "message", "Message Header", "Message Body", "Message Type", "message sequence number", "hop limit", "hop count", "Address Block", "TLV Block", "TLV", "Message TLV", "Address Block TLV", "type" (of TLV), "type extension" (of TLV), "value" (of TLV), "address", "address prefix", and "address object" are to be interpreted as described there. All terms introduced in [RFC6130], including "interface", "MANET interface", "network address", "link", "symmetric link", "1-hop neighbor", "symmetric 1-hop neighbor", "symmetric 2-hop neighbor", "constant", "interface parameter", "router parameter", "Information Base", and "HELLO message" are to be interpreted as described there. Additionally, this specification uses the following terminology: Clausen, et al. Expires April 16, 2012 [Page 7] Internet-Draft OLSRv2 October 2011 Router: A MANET router which implements this protocol. OLSRv2 interface: A MANET interface running this protocol. Routable address: A network address which may be used as the destination of a data packet. A router MUST be able to distinguish a routable address from a non-routable address by direct inspection of the network address, based on global scope address allocations by IANA and/or administrative configuration. Broadcast, multicast and anycast addresses, and addresses which are limited in scope to less than the entire MANET, MUST NOT be considered as routable addresses. Originator address An address which is unique (within the MANET) to a router. A router MUST select an originator address; it MAY choose one of its interface addresses as its originator address; it MAY select either a routable or non-routable address. If it selects a routable address then this MUST be one which the router will accept as destination. An originator address MUST NOT have a prefix length, except for when included in an Address Block where it MAY be associated with a prefix of maximum prefix length (e.g., if the originator address is an IPv6 address, it MUST have either no prefix length, or have a prefix length of 128). Message originator address The originator address of the router which created a message, as deduced from that message by its recipient. The message originator address will usually be included in the message as its element as defined in [RFC5444]. However an exceptional case in a HELLO message is also allowed by this specification, when a router only uses a single address. For all messages used in this specification, including HELLO messages defined in [RFC6130], the recipient MUST be able to deduce an originator address. Willingness: A numerical value between WILL_NEVER and WILL_ALWAYS (both inclusive), that represents the router's willingness to be selected as an MPR. A router has separate willingness values to be a flooding MPR and a routing MPR. Willing symmetric 1-hop neighbor A symmetric 1-hop neighbor of this router that has willingness not equal to WILL_NEVER. Clausen, et al. Expires April 16, 2012 [Page 8] Internet-Draft OLSRv2 October 2011 Multipoint relay (MPR): A router, X, is an MPR for a router, Y, if router Y has indicated its selection of router X as an MPR in a recent HELLO message. Router X may be a flooding MPR for Y, if it is indicated to participate in the flooding process of messages received from router Y, or it may be a routing MPR for Y, if it is indicated to declare link-state information for the link from X to Y. It may also be both at the same time. MPR selector: A router, Y, is a flooding/routing MPR selector of router X if router Y has selected router X as a flooding/routing MPR. MPR flooding: The optimized MANET-wide information distribution mechanism, employed by this protocol, in which a message is relayed by only a reduced subset of the routers in the network. MPR flooding is the mechanism by which flooding reduction is achieved. This document employs the same notational conventions as in [RFC5444] and [RFC6130]. 3. Applicability Statement This protocol: o Is a proactive routing protocol for mobile ad hoc networks (MANETs) [RFC2501]. o Is designed to work in networks with a dynamic topology, and in which messages may be lost, such as due to collisions in wireless networks. o Supports routers that each have one or more participating OLSRv2 interfaces. The set of a router's interfaces may change over time. Each OLSRv2 interface may have one or more network addresses (which may have prefix lengths), and these may also be dynamically changing. o Enables hop-by-hop routing, i.e., each router can use its local information provided by this protocol to route packets. o Continuously maintains routes to all destinations in the network, i.e., routes are instantly available and data traffic is subject to no delays due to route discovery. Consequently, no data traffic buffering is required. Clausen, et al. Expires April 16, 2012 [Page 9] Internet-Draft OLSRv2 October 2011 o Supports routers that have non-OLSRv2 interfaces which may be local to a router or that can serve as gateways towards other networks. o Enables the use of bidirectional additive link metrics to use shortest distance routes (i.e., routes with smallest total of link metrics). Incoming link metric values are to be determined by a process outside this specification. o Is optimized for large and dense networks; the larger and more dense a network, the more optimization can be achieved by using MPRs, compared to the classic link state algorithm. o Uses [RFC5444] as described in its "Intended Usage" appendix and by [RFC5498]. o Allows "external" and "internal" extensibility (adding new message types and adding information to existing messages) as enabled by [RFC5444]. o Is designed to work in a completely distributed manner, and does not depend on any central entity. 4. Protocol Overview and Functioning The objectives of this protocol are for each router to, independently: o Identify all destinations in the network. o Identify a sufficient subset of links in the network, in order that shortest paths can be calculated to all available destinations. o Provide a Routing Set, containing these shortest paths from this router to all destinations (routable addresses and local links). 4.1. Overview These objectives are achieved, for each router, by: o Using [RFC6130] to identify symmetric 1-hop neighbors and symmetric 2-hop neighbors. o Extending [RFC6130] to allow the addition of directional link metrics to advertised links, and to indicate which link metric type is being used by that router. Both incoming and outgoing link metrics may be reported, the latter determined by the Clausen, et al. Expires April 16, 2012 [Page 10] Internet-Draft OLSRv2 October 2011 advertising router. o Selecting flooding MPRs and routing MPRs from among its symmetric 1-hop neighbors such that, for each set of MPRs all symmetric 2-hop neighbors are reachable either directly or via at least one symmetric 1-hop neighbor, using a path of minimum total metric where appropriate. An analysis and examples of MPR selection algorithms are given in [MPR]; a suggested algorithm, appropriately adapted for each set of MPRs, is included in this specification. Note that it is not necessary for routers to use the same algorithm in order to interoperate in the same MANET, but these algorithms must each have the appropriate properties. o Signaling its flooding MPR and routing MPR selections by extending [RFC6130] to report this information in outgoing HELLO messages, by the addition of MPR Address Block TLV(s) associated with the appropriate network addresses. o Extracting its flooding MPR selectors and routing MPR selectors from received HELLO messages, using the included MPR Address Block TLV(s). o Reporting its willingness to be a flooding MPR and to be a routing MPR in HELLO messages, by the addition of an MPR_WILLING Message TLV. The router's flooding willingness indicates how willing it is to participate in MPR flooding and the router's routing willingness indicates how willing it is to be an intermediate node for routing, while still being able to be a routing source or destination even if unwilling to perform either function. o Using the message format specified in [RFC5444], specifically defining a TC (Topology Control) Message Type, used to periodically signal links between routing MPR selectors and itself throughout the MANET. This signaling includes suitable directional neighbor metrics (the best link metric in that direction between those routers). o Allowing its TC messages, as well as HELLO messages, to be included in packets specified in [RFC5444], using the "manet" IP protocol or UDP port as specified in [RFC5498]. o Diffusing TC messages by using a flooding reduction mechanism, denoted "MPR flooding"; only the flooding MPRs of a router will retransmit messages received from (i.e., originated or last relayed by) that router. Note that the indicated extensions to [RFC6130] are of forms permitted by that specification. Clausen, et al. Expires April 16, 2012 [Page 11] Internet-Draft OLSRv2 October 2011 This specification defines: o The requirement to use [RFC6130], its parameters, constants, HELLO messages, and Information Bases, each as extended in this specification. o Two new Information Bases: the Topology Information Base and the Received Message Information Base. o TC messages, which are used for MANET wide signaling (using MPR flooding) of selected topology (link state) information. o A requirement for each router to have an originator address to be included in, or deducible from, HELLO messages and TC messages. o The specification of new Message TLVs and Address Block TLVs that are used in HELLO messages and TC messages, including for reporting link metrics and their usage, willingness to be an MPR, MPR selection, and content sequence number information. Note that the generation of (incoming) link metric values is to be undertaken by a process outside this specification; this specification concerns only the distribution and use of those metrics. o The generation of TC messages from the appropriate information in the Information Bases. o The updating of the Topology Information Base according to received TC messages. o The MPR flooding mechanism, including the inclusion of message originator address and sequence number to manage duplicate messages, using information recorded in the Received Message Information Base. o The response to other events, such as the expiration of information in the Information Bases. This protocol inherits the stability of a link state algorithm, and has the advantage of having routes immediately available when needed, due to its proactive nature. This protocol only interacts with IP through routing table management, and the use of the sending IP address for IP datagrams containing OLSRv2 packets. Clausen, et al. Expires April 16, 2012 [Page 12] Internet-Draft OLSRv2 October 2011 4.2. Routers and Interfaces In order for a router to participate in a MANET using this protocol it MUST have at least one, and possibly more, OLSRv2 interfaces. Each OLSRv2 interface: o Is configured with one or more network addresses, as specified in [RFC6130]. These addresses MUST each be specific to this router, and MUST include any address that will be used as the sending address of any IP packet sent on this OLSRv2 interface. o Has a number of interface parameters, adding to those specified in [RFC6130]. o Has an Interface Information Base, extending that specified in [RFC6130]. o Generates and processes HELLO messages according to [RFC6130], extended as specified in Section 15. In addition to a set of OLSRv2 interfaces as described above, each router: o May have one or more non-OLSRv2 interfaces and/or local attached networks for which this router can accept packets. All routable addresses for which the router is to accept packets MUST be used as an (OLSRv2 or non-OLSRv2) interface network address or as an address of a local attached network of the router. o Has a number of router parameters, adding to those specified in [RFC6130]. o Has a Local Information Base, extending that specified in [RFC6130], including selection of an originator address and recording any locally attached networks. o Has a Neighbor Information Base, extending that specified in [RFC6130] to record MPR selection and advertisement information. o Has a Topology Information Base, recording information received in TC messages. o Has a Received Message Information Base, recording information about received messages to ensure that each TC message is only processed once, and forwarded at most once on each OLSRv2 interface, by a router. Clausen, et al. Expires April 16, 2012 [Page 13] Internet-Draft OLSRv2 October 2011 o Generates and processes TC messages. 4.3. Information Base Overview Each router maintains the Information Bases described in the following sections. These are used for describing the protocol in this specification. An implementation of this protocol MAY maintain this information in the indicated form, or in any other organization which offers access to this information. In particular, note that it is not necessary to remove Tuples from Sets at the exact time indicated, only to behave as if the Tuples were removed at that time. 4.3.1. Local Information Base The Local Information Base is specified in [RFC6130], and contains a router's local configuration. It is extended in this specification to also record an originator address, and to include a router's: o Originator Set, containing addresses that were recently used as this router's originator address, and is used, together with the router's current originator address, to enable a router to recognize and discard control traffic which was originated by the router itself. o Local Attached Network Set, containing network addresses of networks to which this router can act as a gateway, and advertises in its TC messages. 4.3.2. Interface Information Bases The Interface Information Bases, one for each OLSRv2 interface, are specified in [RFC6130], and are extended to also record, in each Link Set, link metric values (incoming and outgoing) and flooding MPR selector information. 4.3.3. Neighbor Information Base The Neighbor Information Base is specified in [RFC6130], and is extended to also record, in the Neighbor Tuple for each neighbor: o Its originator address. o Neighbor metric values, these being the minimum of the link metric values in the indicated direction for all symmetric 1-hop links with that neighbor. o Its willingness to be a flooding MPR and to be a routing MPR. Clausen, et al. Expires April 16, 2012 [Page 14] Internet-Draft OLSRv2 October 2011 o Whether it has been selected by this router as a flooding MPR or as a routing MPR, and whether it is a routing MPR selector of this router. (Whether it is a flooding MPR selector of this neighbor is recorded in the Interface Information Base.) o Whether it is to be advertised in TC messages sent by this router. 4.3.4. Topology Information Base The Topology Information Base in each router contains: o An Advertising Remote Router Set, recording each other router from which TC messages have been received. This is used in order to determine if a received TC message contains fresh or outdated information; a received TC message is ignored in the latter case. o A Router Topology Set, recording links between routers in the MANET, as described by received TC messages. o A Routable Address Topology Set, recording routable addresses in the MANET (available as packet destinations) and from which other router these routable addresses can be directly reached (i.e., in a single IP hop), as reported by received TC messages. o An Attached Network Set, recording networks to which a remote router has advertised that it may act as a gateway. These networks may be reached in one or more IP hops. o A Routing Set, recording routes from this router to all available destinations. The IP routing table is to be updated using this Routing Set. (A router MAY choose to use any or all destination network addresses in the Routing Set to update the IP routing table, this selection is outside the scope of this specification.) The purpose of the Topology Information Base is to record information used, in addition to that in the Local Information Base, the Interface Information Bases and the Neighbor Information Base, to construct the Routing Set (which is also included in the Topology Information Base). This specification describes the calculation of the Routing Set based on a Topology Graph constructed in two phases. First, a "backbone" graph representing the routers in the MANET, and the connectivity between them, is constructed from the Local Information Base, the Neighbor Information Base and the Router Topology Set. Second, this graph is "decorated" with additional destination network addresses using the Local Information Base, the Routable Address Topology Set and the Attached Network Set. Clausen, et al. Expires April 16, 2012 [Page 15] Internet-Draft OLSRv2 October 2011 The Topology Graph does not need to be recorded in the Topology Information Base, it can either be constructed as required when the Routing Set is to be changed, or need not be explicitly constructed (as illustrated in Appendix B). An implementation MAY construct and retain the Topology Graph if preferred. 4.3.5. Received Message Information Base The Received Message Information Base in each router contains: o A Received Set for each OLSRv2 interface, describing TC messages received by this router on that OLSRv2 interface. o A Processed Set, describing TC messages processed by this router. o A Forwarded Set, describing TC messages forwarded by this router. The Received Message Information Base serves the MPR flooding mechanism by ensuring that received messages are forwarded at most once by a router, and also ensures that received messages are processed exactly once by a router. The Received Messages Information Base MAY also record information about other message types that use the MPR flooding mechanism. 4.4. Signaling Overview This protocol generates and processes HELLO messages according to [RFC6130], extended according to Section 15 of this specification to include an originator address, link metrics, and MPR selection information. This specification defines a single message type, the TC message. TC messages are sent by their originating router proactively, at a regular interval. This interval may be fixed, or may be dynamic, for example it may be backed off due to congestion or network stability. TC messages may also be sent as a response to a change in the router itself, or its advertised 1-hop neighborhood, for example on first being selected as a routing MPR. Because TC messages are sent periodically, this protocol is tolerant of unreliable transmissions of TC messages. Message losses may occur more frequently in wireless networks due to collisions or other transmission problems. This protocol may use "jitter", randomized adjustments to message transmission times, to reduce the incidence of collisions, as specified in [RFC5148]. This protocol is tolerant of out of sequence delivery of TC messages due to in transit message reordering. Each router maintains an Clausen, et al. Expires April 16, 2012 [Page 16] Internet-Draft OLSRv2 October 2011 Advertised Neighbor Sequence Number (ANSN) that is incremented when its recorded neighbor information that is to be included in its TC messages changes. This ANSN is included in the router's TC messages. The recipient of a TC message can used this included ANSN to identify which of the information it has received is most recent, even if messages have been reordered while in transit. Only the most recent information received is used, older information received later is discarded. TC messages may be "complete" or "incomplete". A complete TC message advertises all of the originating router's routing MPR selectors, it may also advertise other symmetric 1-hop neighbors. Complete TC messages are generated periodically (and also, optionally, in response to neighborhood changes). Incomplete TC messages may be used to report additions to advertised information, without repeating unchanged information. TC messages, and HELLO messages as extended by this specification, include an originator address for the router that created the message. A TC message reports both the originator addresses and routable addresses of its advertised neighbors, distinguishing the two using an Address Block TLV (an address may be both routable and an originator address). TC messages also report the originator's locally attached networks. TC messages are MPR flooded throughout the MANET. A router retransmits a TC message received on an OLSRv2 interface if and only if the message did not originate at this router and has not been previously forwarded by this router, this is the first time the message has been received on this OLSRv2 interface, and the message is received from (i.e., originated from or was last relayed by) one of this router's flooding MPR selectors. Some TC messages may be MPR flooded over only part of the network, e.g., allowing a router to ensure that nearer routers are kept more up to date than distant routers, such as is used in Fisheye State Routing [FSR] and Fuzzy Sighted Link State routing [FSLS]. This is enabled using [RFC5497]. TC messages include outgoing neighbor metrics that will be used in the selection of routes. 4.5. Link Metrics OLSRv1 [RFC3626] created minimum hop routes to destinations. However in many, if not most, circumstances, better routes (in terms of quality of service for end users) can be created by use of link metrics. Clausen, et al. Expires April 16, 2012 [Page 17] Internet-Draft OLSRv2 October 2011 OLSRv2, as defined in this specification, allows links to have a metric (also known as a cost). Link metrics as defined in OLSRv2 are additive, and the routes that are to be created are minimum length routes, where the length of a route is defined as the sum of the metrics of the links in that route. Link metrics are defined to be directional; the link metric from one router to another may be different from that on the reverse link. The link metric is assessed at the receiver, as on a (typically) wireless link, that is the better informed as to link information. Both incoming and outgoing link information is used by OLSRv2, the distinctions in the specification must be clearly followed. This specification also defines both incoming and outgoing neighbor metrics for each symmetric 1-hop neighbor, these being the minimum value of the link metrics in the same direction for all symmetric links with that neighbor. Note that this means that all neighbor metric values are link metric values and that specification of, for example, link metric value encoding also includes neighbor metric values. This specification does not define the nature of the link metric. However this specification allows, through use of the type extension of a defined Address Block TLV, for link metrics with specific meanings to be defined and either allocated by IANA or privately used. Each HELLO or TC message carrying link (or neighbor) metrics thus indicates which link metric information it is carrying, thus allowing routers to determine if they can interoperate. If link metrics require additional signaling to determine their values, whether in HELLO messages or otherwise, then this is permitted but is outside the scope of this specification. Users are advised that they should carefully consider how to use link metrics. In particular they should not simply default to use of all links with equal metrics (i.e. hop count) for routing without careful consideration of whether that is advisable or not. 4.6. Routing Set Use The purpose of the Routing Set is to determine and record routes (local interface network address and next hop interface network address) to all possible routable addresses advertised by this protocol, as well as of all destinations that are local, i.e., within one hop, to the router (whether using routable addresses or not). Only symmetric links are used in such routes. It is intended that the Routing Set can be used for packet routing, by using its contents to update IP's routing tables. That update, Clausen, et al. Expires April 16, 2012 [Page 18] Internet-Draft OLSRv2 October 2011 and whether any Routing Tuples are not used in IP's routing table, is outside the scope of this specification. The signaling in this specification has been designed so that a "backbone" Topology Graph of routers, each identified by its originator address, with at most one direct connection between any pair of routers, can be constructed (from the Neighbor Set and the Router Topology Set) using a suitable minimum path length algorithm. This Topology Graph can, then, have other network addresses (routable or of symmetric 1-hop neighbors) added to it (using the Interface Information Bases, the Routable Address Topology Set and the Attached Network Set). 5. Protocol Parameters and Constants The parameters and constants used in this specification are those defined in [RFC6130] plus those defined in this section. The separation in [RFC6130] into interface parameters, router parameters and constants is also used in this specification. As for the parameters in [RFC6130], parameters defined in this specification MAY be changed dynamically by a router, and need not be the same on different routers, even in the same MANET, or, for interface parameters, on different interfaces of the same router. 5.1. Protocol and Port Numbers This protocol specifies TC messages, which are included in packets as defined by [RFC5444]. These packets may be sent either using the "manet" protocol number or the "manet" UDP well-known port number, as specified in [RFC5498]. TC messages and HELLO messages [RFC6130] SHOULD, in a given deployment of this protocol, both be using the same of either of IP or UDP, in order that it is possible to combine messages of both protocols into the same [RFC5444] packet for transmission. 5.2. Multicast Address This protocol specifies TC messages, which are included in packets as defined by [RFC5444]. These packets MAY be transmitted using the link local multicast address "LL-MANET-Routers", as specified in [RFC5498]. 5.3. Interface Parameters Clausen, et al. Expires April 16, 2012 [Page 19] Internet-Draft OLSRv2 October 2011 5.3.1. Received Message Validity Time The following parameter manages the validity time of recorded received message information: RX_HOLD_TIME: The period after receipt of a message by the appropriate OLSRv2 interface of this router for which that information is recorded, in order that the message is recognized as having been previously received on this OLSRv2 interface. The following constraints apply to this parameter: o RX_HOLD_TIME > 0 o RX_HOLD_TIME SHOULD be greater than the maximum difference in time that a message may take to traverse the MANET, taking into account any message forwarding jitter as well as propagation, queuing, and processing delays. 5.4. Router Parameters 5.4.1. Local History Times The following router parameter manages the time for which local information is retained: O_HOLD_TIME: The time for which a recently used and replaced originator address is used to recognize the router's own messages. The following constraint apply to this parameter: o O_HOLD_TIME > 0 5.4.2. Link Metric Parameters All routes found using this specification use a single link metric type that is specified by the router parameter LINK_METRIC_TYPE, which may take any value from 0 to 255, inclusive. 5.4.3. Message Intervals The following parameters regulate TC message transmissions by a router. TC messages are usually sent periodically, but MAY also be sent in response to changes in the router's Neighbor Set and/or Local Attached Network Set. In a highly dynamic network, and with a larger value of the parameter TC_INTERVAL and a smaller value of the Clausen, et al. Expires April 16, 2012 [Page 20] Internet-Draft OLSRv2 October 2011 parameter TC_MIN_INTERVAL, TC messages may be transmitted more often in response to changes than periodically. However because a router has no knowledge of, for example, routers remote to it (i.e., beyond two hops away) joining the network, TC messages MUST NOT be sent purely responsively. TC_INTERVAL: The maximum time between the transmission of two successive TC messages by this router. When no TC messages are sent in response to local network changes (by design, or because the local network is not changing) then TC messages SHOULD be sent at a regular interval TC_INTERVAL, possibly modified by jitter as specified in [RFC5148]. TC_MIN_INTERVAL: The minimum interval between transmission of two successive TC messages by this router. (This minimum interval MAY be modified by jitter, as specified in [RFC5148].) The following constraints apply to these parameters: o TC_INTERVAL > 0 o TC_MIN_INTERVAL >= 0 o TC_INTERVAL >= TC_MIN_INTERVAL o If TLVs with Type = INTERVAL_TIME, as defined in [RFC5497], are included in TC messages, then TC_INTERVAL MUST be representable as described in [RFC5497]. 5.4.4. Advertised Information Validity Times The following parameters manage the validity time of information advertised in TC messages: T_HOLD_TIME: Used as the minimum value in the TLV with Type = VALIDITY_TIME included in all TC messages sent by this router. If a single value of parameter TC_HOP_LIMIT (see Section 5.4.7) is used then this will be the only value in that TLV. A_HOLD_TIME: The period during which TC messages are sent after they no longer have any advertised information to report, but are sent in order to accelerate outdated information removal by other routers. The following constraints apply to these parameters: Clausen, et al. Expires April 16, 2012 [Page 21] Internet-Draft OLSRv2 October 2011 o T_HOLD_TIME > 0 o A_HOLD_TIME >= 0 o T_HOLD_TIME >= TC_INTERVAL o If TC messages can be lost, then both T_HOLD_TIME and A_HOLD_TIME SHOULD be significantly greater than TC_INTERVAL; a value >= 3 x TC_INTERVAL is RECOMMENDED. o T_HOLD_TIME MUST be representable as described in [RFC5497]. 5.4.5. Processing and Forwarding Validity Times The following parameters manage the processing and forwarding validity time of recorded message information: P_HOLD_TIME: The period after receipt of a message that is processed by this router for which that information is recorded, in order that the message is not processed again if received again. F_HOLD_TIME: The period after receipt of a message that is forwarded by this router for which that information is recorded, in order that the message is not forwarded again if received again. The following constraints apply to these parameters: o P_HOLD_TIME > 0 o F_HOLD_TIME > 0 o Both of these parameters SHOULD be greater than the maximum difference in time that a message may take to traverse the MANET, taking into account any message forwarding jitter as well as propagation, queuing, and processing delays. 5.4.6. Jitter If jitter, as defined in [RFC5148], is used then the governing jitter parameters are as follows: TP_MAXJITTER: Represents the value of MAXJITTER used in [RFC5148] for periodically generated TC messages sent by this router. Clausen, et al. Expires April 16, 2012 [Page 22] Internet-Draft OLSRv2 October 2011 TT_MAXJITTER: Represents the value of MAXJITTER used in [RFC5148] for externally triggered TC messages sent by this router. F_MAXJITTER: Represents the default value of MAXJITTER used in [RFC5148] for messages forwarded by this router. However before using F_MAXJITTER a router MAY attempt to deduce a more appropriate value of MAXJITTER, for example based on any TLVs with Type = INTERVAL_TIME or Type = VALIDITY_TIME contained in the message to be forwarded. For constraints on these parameters see [RFC5148]. 5.4.7. Hop Limit The parameter TC_HOP_LIMIT is the hop limit set in each TC message. TC_HOP_LIMIT MAY be a single fixed value, or MAY be different in TC messages sent by the same router. However each other router, at any hop count distance, SHOULD see a regular pattern of TC messages in order that meaningful values of TLVs with Type = INTERVAL_TIME and Type = VALIDITY_TIME at each hop count distance can be included as defined in [RFC5497]. Thus the pattern of TC_HOP_LIMIT SHOULD be defined to have this property. For example the repeating pattern (255 4 4) satisfies this property (having period TC_INTERVAL at hop counts up to 4, inclusive, and 3 x TC_INTERVAL at hop counts greater than 4), but the repeating pattern (255 255 4 4) does not satisfy this property because at hop counts greater than 4, message intervals are alternately TC_INTERVAL and 3 x TC_INTERVAL. The following constraints apply to this parameter: o The maximum value of TC_HOP_LIMIT >= the network diameter in hops, a value of 255 is RECOMMENDED. Note that if using a pattern of different values of TC_HOP_LIMIT as described above, then only the maximum value in the pattern is so constrained. o All values of TC_HOP_LIMIT >= 2. 5.4.8. Willingness Each router has two willingness parameters: WILL_FLOODING and WILL_ROUTING, each of which MUST be in the range WILL_NEVER to WILL_ALWAYS, inclusive. WILL_FLOODING represents the router's willingness to be selected as a flooding MPR and hence to participate in MPR flooding, in particular of TC messages. Clausen, et al. Expires April 16, 2012 [Page 23] Internet-Draft OLSRv2 October 2011 WILL_ROUTING represents the router's willingness to be selected as a routing MPR and hence to be an intermediate router on routes. In either case, the higher the value, the greater the router's willingness to be a flooding or routing MPR, respectively. If a router has a willingness value of WILL_NEVER (the lowest possible value) it does not perform the corresponding task. A MANET using this protocol with too many routers having either willingness value equal to WILL_NEVER will not function; it MUST be ensured, by administrative or other means, that this does not happen. If a router has a willingness value equal to WILL_ALWAYS (the highest possible value) then it will always be selected as a flooding or routing MPR, respectively, by all symmetric 1-hop neighbors. A MANET in which all routers have WILL_FLOODING = WILL_ALWAYS, the flooding operation will effectively disable optimizations, and perform as blind flooding. A router, which has WILL_ROUTING = WILL_NEVER will not act as an intermediate router in the MANET. Such a router can, act as a source, destination or gateway to another routing domain. Different routers MAY have different values for WILL_FLOODING and/or WILL_ROUTING. A router that has both WILL_FLOODING = WILL_DEFAULT and WILL_ROUTING = WILL_DEFAULT need not include an MPR_WILLING TLV in its HELLO messages. The following constraints apply to these parameters: o WILL_FLOODING >= WILL_NEVER o WILL_FLOODING <= WILL_ALWAYS o WILL_ROUTING >= WILL_NEVER o WILL_ROUTING <= WILL_ALWAYS 5.5. Parameter Change Constraints If protocol parameters are changed dynamically, then the constraints in this section apply. RX_HOLD_TIME * If RX_HOLD_TIME for an OLSRv2 interface changes, then the expiry time for all Received Tuples for that OLSRv2 interface MAY be changed. Clausen, et al. Expires April 16, 2012 [Page 24] Internet-Draft OLSRv2 October 2011 O_HOLD_TIME * If O_HOLD_TIME for a router changes, then the expiry time for all Originator Tuples MAY be changed. TC_INTERVAL * If the TC_INTERVAL for a router increases, then the next TC message generated by this router MUST be generated according to the previous, shorter, TC_INTERVAL. Additional subsequent TC messages MAY be generated according to the previous, shorter, TC_INTERVAL. * If the TC_INTERVAL for a router decreases, then the following TC messages from this router MUST be generated according to the current, shorter, TC_INTERVAL. P_HOLD_TIME * If P_HOLD_TIME changes, then the expiry time for all Processed Tuples MAY be changed. F_HOLD_TIME * If F_HOLD_TIME changes, then the expiry time for all Forwarded Tuples MAY be changed. TP_MAXJITTER * If TP_MAXJITTER changes, then the periodic TC message schedule on this router MAY be changed immediately. TT_MAXJITTER * If TT_MAXJITTER changes, then externally triggered TC messages on this router MAY be rescheduled. F_MAXJITTER * If F_MAXJITTER changes, then TC messages waiting to be forwarded with a delay based on this parameter MAY be rescheduled. TC_HOP_LIMIT * If TC_HOP_LIMIT changes, and the router uses multiple values after the change, then message intervals and validity times included in TC messages MUST be respected. The simplest way to Clausen, et al. Expires April 16, 2012 [Page 25] Internet-Draft OLSRv2 October 2011 do this is to start any new repeating pattern of TC_HOP_LIMIT values with its largest value. LINK_METRIC_TYPE * If LINK_METRIC_TYPE changes then all link metric information recorded by the router is invalid. The router MUST take the following actions, and all consequent actions described in Section 17 and [RFC6130]. + For each Link Tuple in any Link Set, either update L_in_metric (the value MAXIMUM_METRIC MAY be used) or remove the Link Tuple from the Link Set. + For each Link Tuple that is not removed, set: - L_out_metric := UNKNOWN_METRIC; - L_SYM_time := expired; - L_MPR_selector := false. + Remove all Router Topology Tuples, Routable Address Topology Tuples, Attached Network Tuples and Routing Tuples from their respective protocol sets in the Topology Information Base. 5.6. Constants 5.6.1. Link Metric Constants The constant minimum, maximum and default metric values are defined by: o MINIMUM_METRIC := 1 o MAXIMUM_METRIC := 16776960 o DEFAULT_METRIC := 256 The symbolic value UNKNOWN_METRIC is defined in Section 6.1. 5.6.2. Willingness Constants The constant minimum, maximum and default willingness values are defined by: Clausen, et al. Expires April 16, 2012 [Page 26] Internet-Draft OLSRv2 October 2011 o WILL_NEVER := 0 o WILL_ALWAYS := 15 o WILL_DEFAULT := 7 6. Link Metric Values A router records a link metric value for each direction of a link of which it has knowledge. These link metric values are used to create metrics for routes by the addition of link metric values. 6.1. Link Metric Representation Link metrics are reported in messages using a compressed representation that occupies 12 bits, a 4 bit field and an 8 bit field. The compressed representation represents positive integer values with a minimum value of 1 and a maximum value that is slightly smaller than the maximum 24 bit value. Only those values that have exact representation in the compressed form are used. Route metrics are the summation of no more then 255 link metric values, and can therefore be represented using no more than 32 bits. Link and route metrics used in the Information Bases defined in this specification refer to the uncompressed values, and arithmetic involving them does likewise, and assumes full precision in the result. (How an implementation records the values is not part of this specification, as long as it behaves as if recording uncompressed values. An implementation can, for example, use 32 bit values for all link and route metrics.) In some cases a link metric value may be unknown. This is indicated in this specification by the value UNKNOWN_METRIC. An implementation may use any representation of UNKNOWN_METRIC as it is never included in messages or used in any computation. (Possible values are zero, or any value greater than the maximum representable metric value.) 6.2. Link Metric Compressed Form The 12-bit compressed form of a link metric uses a modified form of a representation with as 8-bit mantissa (denoted b) and a 4-bit exponent (denoted a). Note that if represented as the 12 bit value 256a+b then the ordering of those 12 bit values is identical to the ordering of the represented values. The value so represented is (257+b)2^a - 256, where ^ denotes exponentiation. This has a minimum value (when a = 0 and b = 0) of MINIMUM_METRIC = 1 and a maximum value (when a = 15 and b = 255) of Clausen, et al. Expires April 16, 2012 [Page 27] Internet-Draft OLSRv2 October 2011 MAXIMUM_METRIC = 2^24 - 256. An algorithm for computing a and b for the smallest representable value not less than a link metric value v such that MINIMUM_METRIC <= v <= MAXIMUM_METRIC is: 1. Find the smallest integer a such that v + 256 <= 2^(a + 9). 2. Set b := (v - 256(2^a - 1)) / (2^a) - 1, rounded up to the nearest integer. To allow for more efficient messages, a default link metric DEFAULT_METRIC is defined, which can be omitted from messages. Note that this is not the same as the link metric value that should be used when this specification requires a link metric, but no information about a link, beyond that a HELLO message has been received using that link, is available. In this case the link metric used SHOULD be MAXIMUM_METRIC. 7. Local Information Base The Local Information Base, as defined for each router in [RFC6130], is extended by this protocol by: o Recording the router's originator address. The originator address MUST be unique to this router. It MUST NOT be used by any other router as an originator address. It MAY be included in any network address in any I_local_iface_addr_list of this router, it MUST NOT be included in any network address in any I_local_iface_addr_list of any other router. It MAY be included in, but MUST NOT be equal to, the AL_net_addr in any Local Attached Network Tuple in this or any other router. o The addition of an Originator Set, defined in Section 7.1, and a Local Attached Network Set, defined in Section 7.2. All routable addresses of the router for which it is to accept packets as destination MUST be included in the Local Interface Set or the Local Attached Network Set. 7.1. Originator Set A router's Originator Set records addresses that were recently used as originator addresses by this router. If a router's originator address is immutable then this set is always empty and MAY be omitted. It consists of Originator Tuples: (O_orig_addr, O_time) Clausen, et al. Expires April 16, 2012 [Page 28] Internet-Draft OLSRv2 October 2011 where: O_orig_addr is a recently used originator address; note that this does not include a prefix length; O_time specifies the time at which this Tuple expires and MUST be removed. 7.2. Local Attached Network Set A router's Local Attached Network Set records its local non-OLSRv2 interfaces via which it can act as gateways to other networks. The Local Attached Network Set is not modified by this protocol. This protocol MAY respond to changes to the Local Attached Network Set, which MUST reflect corresponding changes in the router's status. It consists of Local Attached Network Tuples: (AL_net_addr, AL_dist, AL_metric) where: AL_net_addr is the network address of an attached network which can be reached via this router. This SHOULD be a routable address. It is constrained as described below. AL_dist is the number of hops to the network with network address AL_net_addr from this router. AL_metric is the metric of the link to the attached network with address AL_net_addr from this router; Attached networks local to this router only (i.e., not reachable except via this router) SHOULD be treated as local non-MANET interfaces, and added to the Local Interface Set, as specified in [RFC6130], rather than be added to the Local Attached Network Set. Because an attached network is not specific to the router, and may be outside the MANET, an attached network MAY also be attached to other routers. Routing to an AL_net_addr will use maximum prefix length matching; consequently an AL_net_addr MAY include, but MUST NOT equal or be included in, any network address which is of any interface of any router (i.e., is included in any I_local_iface_addr_list) or equal any router's originator address. It is not the responsibility of this protocol to maintain routes from this router to networks recorded in the Local Attached Network Set. Local Attached Neighbor Tuples are removed from the Local Attached Clausen, et al. Expires April 16, 2012 [Page 29] Internet-Draft OLSRv2 October 2011 Network Set only when the routers' local attached network configuration changes, i.e., they are not subject to timer-based expiration or changes due to received messages. 8. Interface Information Base An Interface Information Base, as defined in [RFC6130], is maintained for each OLSRv2 interface. Its Link Set and 2-Hop Set are modified by this protocol. 8.1. Link Set The Link Set is modified by adding these additional elements to each Link Tuple: L_in_metric is the metric of the link from the OLSRv2 interface with addresses L_neighbor_iface_addr_list to this OLSRv2 interface; L_out_metric is the metric of the link to the OLSRv2 interface with addresses L_neighbor_iface_addr_list from this OLSRv2 interface; L_mpr_selector is a boolean flag, describing if this neighbor has selected this router as a flooding MPR, i.e., is a flooding MPR selector of this router. L_in_metric will be specified by a process that is external to this specification. Any Link Tuple with L_status = HEARD or L_status = SYMMETRIC MUST have a specified value of L_in_metric. A Link Tuple created (but not updated) by [RFC6130] MUST set: o L_in_metric := UNKNOWN_METRIC; o L_out_metric := UNKNOWN_METRIC; o L_mpr_selector := false. 8.2. 2-Hop Set The 2-Hop Set is modified by adding these additional elements to each 2-Hop Tuple: N2_in_metric is the neighbor metric from the router with address N2_2hop_iface_addr to the router with OLSRv2 interface addresses N2_neighbor_iface_addr_list; Clausen, et al. Expires April 16, 2012 [Page 30] Internet-Draft OLSRv2 October 2011 N2_out_metric is the neighbor metric to the router with address N2_2hop_iface_addr from the router with OLSRv2 interface addresses N2_neighbor_iface_addr_list. A 2-Hop Tuple created (but not updated) by [RFC6130] MUST set: o N2_in_metric := UNKNOWN_METRIC; o N2_out_metric := UNKNOWN_METRIC. 9. Neighbor Information Base An Neighbor Information Base, as defined in [RFC6130], is maintained for each router. It is modified by this protocol by adding these additional elements to each Neighbor Tuple in the Neighbor Set: N_orig_addr is the neighbor's originator address, which may be unknown. Note that this originator address does not include a prefix length; N_in_metric is the neighbor metric of any link from this neighbor to this router, i.e., the minimum of all corresponding L_in_metric with L_status = SYMMETRIC, UNKNOWN_METRIC if there are no such Link Tuples; N_out_metric is the neighbor metric of any link from this router to this neighbor, i.e., the minimum of all corresponding L_out_metric with L_status = SYMMETRIC, UNKNOWN_METRIC if there are no such Link Tuples; N_will_flooding is the neighbor's willingness to be selected as a flooding MPR, in the range from WILL_NEVER to WILL_ALWAYS, both inclusive; N_will_routing is the neighbor's willingness to be selected as a routing MPR, in the range from WILL_NEVER to WILL_ALWAYS, both inclusive; N_flooding_mpr is a boolean flag, describing if this neighbor is selected as a flooding MPR by this router; N_routing_mpr is a boolean flag, describing if this neighbor is selected as a routing MPR by this router; N_mpr_selector is a boolean flag, describing if this neighbor has selected this router as a routing MPR, i.e., is a routing MPR selector of this router. Clausen, et al. Expires April 16, 2012 [Page 31] Internet-Draft OLSRv2 October 2011 N_advertised is a boolean flag, describing if this router has elected to advertise a link to this neighbor in its TC messages. A Neighbor Tuple created (but not updated) by [RFC6130] MUST set: o N_orig_addr := unknown; o N_in_metric := UNKNOWN_METRIC; o N_out_metric := UNKNOWN_METRIC; o N_will_flooding := WILL_NEVER; o N_will_routing := WILL_NEVER; o N_routing_mpr := false; o N_flooding_mpr := false; o N_mpr_selector := false; o N_advertised := false. The Neighbor Information Base also includes a variable, the Advertised Neighbor Sequence Number (ANSN), whose value is included in TC messages to indicate the freshness of the information transmitted. The ANSN is incremented whenever advertised information (the originator and routable addresses included in Neighbor Tuples with N_advertised = true, and local attached networks recorded in the Local Attached Network Set in the Local Information Base) changes, including addition or removal of such information. 10. Topology Information Base The Topology Information Base, defined for each router by this specification, stores information received in TC messages, in the Advertising Remote Router Set, the Router Topology Set, the Routable Address Topology Set and the Attached Network Set. Additionally, a Routing Set is maintained, derived from the information recorded in the Local Information Base, the Interface Information Bases, the Neighbor Information Base and the rest of the Topology Information Base. 10.1. Advertising Remote Router Set A router's Advertising Remote Router Set records information describing each remote router in the network that transmits TC Clausen, et al. Expires April 16, 2012 [Page 32] Internet-Draft OLSRv2 October 2011 messages, allowing outdated TC messages to be recognized and discarded. It consists of Advertising Remote Router Tuples: (AR_orig_addr, AR_seq_number, AR_time) where: AR_orig_addr is the originator address of a received TC message, note that this does not include a prefix length; AR_seq_number is the greatest ANSN in any TC message received which originated from the router with originator address AR_orig_addr (i.e., which contributed to the information contained in this Tuple); AR_time is the time at which this Tuple expires and MUST be removed. 10.2. Router Topology Set A router's Topology Set records topology information about the links between routers in the MANET. It consists of Router Topology Tuples: (TR_from_orig_addr, TR_to_orig_addr, TR_seq_number, TR_metric, TR_time) where: TR_from_orig_addr is the originator address of a router which can reach the router with originator address TR_to_orig_addr in one hop, note that this does not include a prefix length; TR_to_orig_addr is the originator address of a router which can be reached by the router with originator address TR_to_orig_addr in one hop, note that this does not include a prefix length; TR_seq_number is the greatest ANSN in any TC message received which originated from the router with originator address TR_from_orig_addr (i.e., which contributed to the information contained in this Tuple); TR_metric is the neighbor metric from the router with originator address TR_from_orig_addr to the router with originator address TR_to_orig_addr; TR_time specifies the time at which this Tuple expires and MUST be removed. Clausen, et al. Expires April 16, 2012 [Page 33] Internet-Draft OLSRv2 October 2011 10.3. Routable Address Topology Set A router's Routable Address Topology Set records topology information about the routable addresses within the MANET, and via which routers they may be reached. It consists of Routable Address Topology Tuples: (TA_from_orig_addr, TA_dest_addr, TA_seq_number, TA_metric, TA_time) where: TA_from_orig_addr is the originator address of a router which can reach the router with routable address TA_dest_addr in one hop, note that this does not include a prefix length; TA_dest_addr is a routable address of a router which can be reached by the router with originator address TA_from_orig_addr in one hop; TA_seq_number is the greatest ANSN in any TC message received which originated from the router with originator address TA_from_orig_addr (i.e., which contributed to the information contained in this Tuple); TA_metric is the neighbor metric from the router with originator address TA_from_orig_addr to the router with OLSRv2 interface address TA_dest_addr; TA_time specifies the time at which this Tuple expires and MUST be removed. 10.4. Attached Network Set A router's Attached Network Set records information about networks (which may be outside the MANET) attached to other routers and their routable addresses. It consists of Attached Network Tuples: (AN_orig_addr, AN_net_addr, AN_seq_number, AN_dist, AN_metric, AN_time) where: AN_orig_addr is the originator address of a router which can act as gateway to the network with network address AN_net_addr, note that this does not include a prefix length; Clausen, et al. Expires April 16, 2012 [Page 34] Internet-Draft OLSRv2 October 2011 AN_net_addr is the network address of an attached network, which may be reached via the router with originator address AN_orig_addr; AN_seq_number is the greatest ANSN in any TC message received which originated from the router with originator address AN_orig_addr (i.e., which contributed to the information contained in this Tuple); AN_dist is the number of hops to the network with network address AN_net_addr from the router with originator address AN_orig_addr; AN_metric is the metric of the link from the router with originator address AN_orig_addr to the attached network with address AN_net_addr; AN_time specifies the time at which this Tuple expires and MUST be removed. 10.5. Routing Set A router's Routing Set records the first hop along a selected path to each destination for which any such path is known. It consists of Routing Tuples: (R_dest_addr, R_next_iface_addr, R_local_iface_addr, R_dist, R_metric) where: R_dest_addr is the network address of the destination, either the network address of an interface of a destination router, or the network address of an attached network; R_next_iface_addr is the network address of the "next hop" on the selected path to the destination; R_local_iface_addr is the network address of the local OLSRv2 interface over which a packet MUST be sent to reach the destination by the selected path. R_dist is the number of hops on the selected path to the destination; R_metric is the metric of the route to the destination with address R_dest_addr. The Routing Set for a router is derived from the contents of other Clausen, et al. Expires April 16, 2012 [Page 35] Internet-Draft OLSRv2 October 2011 protocol sets of the router (the Link Sets, the Neighbor Set, the Router Topology Set, the Routable Address Topology Set, the Attached Network Set, and OPTIONALLY the 2-Hop Sets). The Routing Set is updated (Routing Tuples added or removed, or the complete Routing Set recalculated) when routing paths are calculated, based on changes to these other protocol sets. Routing Tuples are not subject to timer- based expiration. 11. Received Message Information Base The Received Message Information Base, defined by this specification, records information required to ensure that a message is processed at most once and is forwarded at most once per OLSRv2 interface of a router, using MPR flooding. 11.1. Received Set A router has a Received Set per OLSRv2 interface. Each Received Set records the signatures of messages which have been received over that OLSRv2 interface. Each consists of Received Tuples: (RX_type, RX_orig_addr, RX_seq_number, RX_time) where: RX_type is the received Message Type; RX_orig_addr is the originator address of the received message, note that this does not include a prefix length; RX_seq_number is the message sequence number of the received message; RX_time specifies the time at which this Tuple expires and MUST be removed. 11.2. Processed Set A router has a single Processed Set which records signatures of messages which have been processed by the router. It consists of Processed Tuples: (P_type, P_orig_addr, P_seq_number, P_time) where: P_type is the processed Message Type; Clausen, et al. Expires April 16, 2012 [Page 36] Internet-Draft OLSRv2 October 2011 P_orig_addr is the originator address of the processed message, note that this does not include a prefix length; P_seq_number is the message sequence number of the processed message; P_time specifies the time at which this Tuple expires and MUST be removed. 11.3. Forwarded Set A router has a single Forwarded Set which records signatures of messages which have been forwarded by the router. It consists of Forwarded Tuples: (F_type, F_orig_addr, F_seq_number, F_time) where: F_type is the forwarded Message Type; F_orig_addr is the originator address of the forwarded message, note that this does not include a prefix length; F_seq_number is the message sequence number of the forwarded message; F_time specifies the time at which this Tuple expires and MUST be removed. 12. Information Base Properties As part of this specification, in a number of cases there is a natural correspondence from a Protocol Tuple in one Protocol Set to a single Protocol Tuple in another Protocol Set, in the same or another Information Base. The latter Protocol Tuple is referred to as "corresponding" to the former Protocol Tuple. Specific examples of corresponding Protocol Tuples include: o There is a Local Interface Tuple corresponding to each Link Tuple, where the Link Tuple is in the Link Set for an OLSRv2 interface, and the Local Interface Tuple represents that OLSRv2 interface. o There is a Neighbor Tuple corresponding to each Link Tuple which has L_HEARD_time not expired, such that N_neighbor_addr_list contains L_neighbor_iface_addr_list. Clausen, et al. Expires April 16, 2012 [Page 37] Internet-Draft OLSRv2 October 2011 o There is a Link Tuple (in the Link Set in the same Interface Information Base) corresponding to each 2-Hop Tuple such that L_neighbor_iface_addr_list = N2_neighbor_iface_addr_list. o There is a Neighbor Tuple corresponding to each 2-Hop Tuple, such that N_neighbor_addr_list contains N2_neighbor_iface_addr_list. (This is the Neighbor Tuple corresponding to the Link Tuple that corresponds to the 2-Hop Tuple.) o There is an Advertising Remote Router Tuple corresponding to each Router Topology Tuple such that AR_orig_addr = TR_from_orig_addr. o There is an Advertising Remote Router Tuple corresponding to each Routable Address Topology Tuple such that AR_orig_addr = TA_from_orig_addr. o There is an Advertising Remote Router Tuple corresponding to each Attached Network Tuple such that AR_orig_addr = AN_orig_addr. o There is an Neighbor Tuple corresponding to each Routing Tuple such that N_neighbor_addr_list contains R_next_iface_addr. Addresses or network addresses with the following properties are considered as "fully owned" by a router when processing a received message: o Equaling its originator address, OR; o Equaling the O_orig_addr in an Originator Tuple, OR; o Equaling or being a sub-range of the I_local_iface_addr_list in a Local Interface Tuple, OR; o Equaling or being a sub-range of the IR_local_iface_addr in a Removed Interface Address Tuple, OR; o Equaling an AL_net_addr in a Local Attached Network Tuple. Addresses or network addresses with the following properties are considered as "partially owned" (which may include being fully owned) by a router when processing a received message: o Overlapping (equaling or containing) its originator address, OR; o Overlapping (equaling or containing) the O_orig_addr in an Originator Tuple, OR; Clausen, et al. Expires April 16, 2012 [Page 38] Internet-Draft OLSRv2 October 2011 o Overlapping the I_local_iface_addr_list in a Local Interface Tuple, OR; o Overlapping the IR_local_iface_addr in a Removed Interface Address Tuple, OR; o Equaling or having as a sub-range an AL_net_addr in a Local Attached Network Tuple. 13. Packets and Messages The packet and message format used by this protocol is defined in [RFC5444]. Except as otherwise noted, options defined in [RFC5444] may be freely used, in particular alternative formats defined by packet, message, Address Block and TLV flags. This section describes the usage of the packets and messages defined in [RFC5444] by this specification, and the TLVs defined by, and used in, this specification. 13.1. Messages Routers using this protocol exchange information through messages. The message types used by this protocol are the HELLO message and the TC message. The HELLO message is defined by [RFC6130] and extended by this specification, see Section 15. The TC message is defined by this specification, see Section 16. 13.2. Packets One or more messages sent by a router at the same time SHOULD be combined into a single packet, subject to any constraints on maximum packet size (such as derived from the MTU over a local single hop) that MAY be imposed. These messages may have originated at the sending router, or have originated at another router and are being forwarded by the sending router. Messages with different originating routers MAY be combined for transmission within the same packet. Messages from other protocols defined using [RFC5444], including but not limited to [RFC6130], MAY be combined for transmission within the same packet. This specification does not define or use any contents of the Packet Header. Forwarded messages MAY be jittered as described in [RFC5148], including the observation that the forwarding jitter of all messages received in a single packet SHOULD be the same. The value of MAXJITTER used in jittering a forwarded message MAY be based on information in that message (in particular any Message TLVs with Type = INTERVAL_TIME or Type = VALIDITY_TIME) or otherwise SHOULD be with Clausen, et al. Expires April 16, 2012 [Page 39] Internet-Draft OLSRv2 October 2011 a maximum delay of F_MAXJITTER. A router MAY modify the jitter applied to a message in order to more efficiently combine messages in packets, as long as the maximum jitter is not exceeded. 13.3. TLVs This specification defines 2 Message TLVs and 4 Address Block TLVs. All references in this specification to TLVs that do not indicate a type extension, assume Type Extension = 0. TLVs in processed messages with a type extension which is neither zero as so assumed, nor a specifically indicated non-zero type extension, are ignored. 13.3.1. Message TLVs The MPR_WILLING TLV is used in HELLO messages. A message MUST NOT contain more than one MPR_WILLING TLV. +-------------+--------------+--------------------------------------+ | Type | Value Length | Value | +-------------+--------------+--------------------------------------+ | MPR_WILLING | 1 octet | Bits 0-3 encode the parameter | | | | WILL_FLOODING; bits 4-7 encode the | | | | parameter WILL_ROUTING. | +-------------+--------------+--------------------------------------+ Table 1: MPR_WILLING TLV definition The CONT_SEQ_NUM TLV is used in TC messages. message MUST NOT contain more than one CONT_SEQ_NUM TLV. +--------------+--------------+-------------------------------------+ | Type | Value Length | Value | +--------------+--------------+-------------------------------------+ | CONT_SEQ_NUM | 2 octets | The ANSN contained in the Neighbor | | | | Information Base. | +--------------+--------------+-------------------------------------+ Table 2: CONT_SEQ_NUM TLV definition 13.3.2. Address Block TLVs The LINK_METRIC TLV is used in HELLO messages and TC messages. It MAY use any type extension; only LINK_METRIC TLVs with type extension equal to LINK_METRIC_TYPE will be used by this specification. At most one link metric value of any given kind (link or neighbor) and direction may be associated with any address. Clausen, et al. Expires April 16, 2012 [Page 40] Internet-Draft OLSRv2 October 2011 +-------------+--------------+--------------------------------------+ | Type | Value Length | Value | +-------------+--------------+--------------------------------------+ | LINK_METRIC | 2 octets | Bits 0-3 indicates kind(s) and | | | | direction(s), Bits 4-7 indicate | | | | exponent (a), Bits 8-15 indicate | | | | mantissa (b) | +-------------+--------------+--------------------------------------+ Table 3: LINK_METRIC TLV definition The exponent and mantissa use the representation defined in Section 6. Each bit of the types and directions sub-field, if set ('1') indicates that the link metric is of the indicated kind and direction. Any combination of these bits MAY be used. +-----+-----------------+-----------+ | Bit | Kind | Direction | +-----+-----------------+-----------+ | 0 | Link metric | Incoming | | 1 | Link metric | Outgoing | | 2 | Neighbor metric | Incoming | | 3 | Neighbor metric | Outgoing | +-----+-----------------+-----------+ Table 4: LINK_METRIC TLV types and directions The MPR TLV is used in HELLO messages, and indicates that an address with which it is associated is of a symmetric 1-hop neighbor that has been selected as an MPR. +------+--------------+---------------------------------------------+ | Type | Value Length | Value | +------+--------------+---------------------------------------------+ | MPR | 1 octet | FLOODING indicates that the corresponding | | | | address is of a neighbor selected as a | | | | flooding MPR, ROUTING indicates that the | | | | corresponding address is of a neighbor | | | | selected as a routing MPR, FLOOD_ROUTE | | | | indicates both | +------+--------------+---------------------------------------------+ Table 5: MPR TLV definition The NBR_ADDR_TYPE TLV is used in TC messages. Clausen, et al. Expires April 16, 2012 [Page 41] Internet-Draft OLSRv2 October 2011 +---------------+--------------+------------------------------------+ | Type | Value Length | Value | +---------------+--------------+------------------------------------+ | NBR_ADDR_TYPE | 1 octet | ORIGINATOR indicates that the | | | | corresponding address (which MUST | | | | have maximum prefix length) is an | | | | originator address, ROUTABLE | | | | indicates that the corresponding | | | | network address is a routable | | | | address of an interface, | | | | ROUTABLE_ORIG indicates that the | | | | corresponding address is both | +---------------+--------------+------------------------------------+ Table 6: NBR_ADDR_TYPE TLV definition If an address is both an originator address and a routable address, then it may be associated with either one Address Block TLV with Type := NBR_ADDR_TYPE and Value := ROUTABLE_ORIG, or with two Address Block TLVs with Type:= NBR_ADDR_TYPE, one with Value := ORIGINATOR and one with Value := ROUTABLE. The GATEWAY TLV is used in TC messages. At most one GATEWAY TLV may be associated with any address. +---------+--------------+-------------------------------------+ | Type | Value Length | Value | +---------+--------------+-------------------------------------+ | GATEWAY | 1 octet | Number of hops to attached network. | +---------+--------------+-------------------------------------+ Table 7: GATEWAY TLV definition All address objects included in a TC message according to this specification MUST be associated either with at least one TLV with Type := NBR_ADDR_TYPE or with a TLV with Type := GATEWAY, but not both. Any other address objects MAY be included in Address Blocks in a TC message, but are ignored by this specification. 14. Message Processing and Forwarding This section describes the optimized flooding operation (MPR flooding) used when control messages, as instances of [RFC5444], are intended for MANET wide distribution. This flooding mechanism defines when a received message is, or is not, processed and/or forwarded. This flooding mechanism is used by this protocol and MAY be used by Clausen, et al. Expires April 16, 2012 [Page 42] Internet-Draft OLSRv2 October 2011 extensions to this protocol which define, and hence own, other message types, to manage processing and/or forwarding of these messages. This specification contains elements (P_type, RX_type, F_type) required only for such usage. This flooding mechanism is always used for TC messages (see Section 16). Received HELLO messages (see Section 15 are, unless invalid, always processed, and never forwarded by this flooding mechanism. They thus do not need to be recorded in the Received Message Information Base. The processing selection and forwarding mechanisms are designed to only need to parse the Message Header in order to determine whether a message is to be processed and/or forwarded, and not to have to parse the Message Body even if the message is forwarded (but not processed). An implementation MAY only parse the Message Body if necessary, or MAY always parse the Message Body and reject the message if it cannot be so parsed, or any other error is identified. An implementation MUST discard the message silently if it is unable to parse the Message Header or (if attempted) the Message Body, or if a message (other than a HELLO message) does not include a message sequence number. 14.1. Actions when Receiving a Message On receiving a message of a type specified to be using this mechanism, which includes the TC messages defined in this specification, a router MUST perform the following: 1. If the router recognizes from the originator address of the message that the message is one which the receiving router itself originated (i.e., the message originator address is the originator address of this router, or is an O_orig_addr in an Originator Tuple) then the message MUST be silently discarded. 2. Otherwise: 1. If the message is of a type which may be processed, then the message is considered for processing according to Section 14.2. 2. If the message is of a type which may be forwarded, AND: + is present and > 1, AND; + is not present or < 255; Clausen, et al. Expires April 16, 2012 [Page 43] Internet-Draft OLSRv2 October 2011 then the message is considered for forwarding according to Section 14.3. 14.2. Message Considered for Processing If a message (the "current message") is considered for processing, then the following tasks MUST be performed: 1. If the sending address (i.e., the source address of the IP datagram containing the current message) does not match (taking into account any address prefix) a network address in an L_neighbor_iface_addr_list of a Link Tuple, with L_status = SYMMETRIC, in the Link Set for the OLSRv2 interface on which the current message was received (the "receiving interface") then processing the current message is OPTIONAL. If the current message is not processed then the following steps are not carried out. 2. If a Processed Tuple exists with: * P_type = the Message Type of the current message, AND; * P_orig_addr = the originator address of the current message, AND; * P_seq_number = the message sequence number of the current message; then the current message MUST NOT be processed. 3. Otherwise: 1. Create a Processed Tuple with: + P_type := the Message Type of the current message; + P_orig_addr := the originator address of the current message; + P_seq_number := the sequence number of the current message; + P_time := current time + P_HOLD_TIME. 2. Process the current message according to its Message Type. For a TC message this is as defined in Section 16.3. Clausen, et al. Expires April 16, 2012 [Page 44] Internet-Draft OLSRv2 October 2011 14.3. Message Considered for Forwarding If a message (the "current message") is considered for forwarding, then the following tasks MUST be performed: 1. If the sending address (i.e., the source address of the IP datagram containing the current message) does not match (taking into account any address prefix) a network address in an L_neighbor_iface_addr_list of a Link Tuple, with L_status = SYMMETRIC, in the Link Set for the OLSRv2 interface on which the current message was received (the "receiving interface") then the current message MUST be silently discarded. 2. Otherwise: 1. If a Received Tuple exists in the Received Set for the receiving interface, with: + RX_type = the Message Type of the current message, AND; + RX_orig_addr = the originator address of the current message, AND; + RX_seq_number = the sequence number of the current message; then the current message MUST be silently discarded. 2. Otherwise: 1. Create a Received Tuple in the Received Set for the receiving interface with: - RX_type := the Message Type of the current message; - RX_orig_addr := originator address of the current message; - RX_seq_number := sequence number of the current message; - RX_time := current time + RX_HOLD_TIME. 2. If a Forwarded Tuple exists with: - F_type = the Message Type of the current message, AND; Clausen, et al. Expires April 16, 2012 [Page 45] Internet-Draft OLSRv2 October 2011 - F_orig_addr = the originator address of the current message, AND; - F_seq_number = the sequence number of the current message. then the current message MUST be silently discarded. 3. Otherwise if the sending address matches (taking account of any address prefix) any network address in an L_neighbor_iface_addr_list of a Link Tuple in the Link Set for the receiving OLSRv2 interface that has L_status = SYMMETRIC and whose corresponding Neighbor Tuple has N_mpr_selector = true, then: 1. Create a Forwarded Tuple with: o F_type := the Message Type of the current message; o F_orig_addr := originator address of the current message; o F_seq_number := sequence number of the current message; o F_time := current time + F_HOLD_TIME. 2. The Message Header of the current message is modified by: o if present, decrement in the Message Header by 1, AND; o if present, increment in the Message Header by 1. 3. The message is transmitted over all OLSRv2 interfaces, as described in Section 13. 15. HELLO Messages The HELLO message Message Type is owned by [RFC6130], and thus HELLO messages are generated, transmitted, received and processed by [RFC6130]. This protocol, as permitted by [RFC6130], also uses HELLO messages, including adding to HELLO message generation, and implementing additional processing based on received HELLO messages. HELLO messages are not forwarded by [RFC6130] or by this specification. Clausen, et al. Expires April 16, 2012 [Page 46] Internet-Draft OLSRv2 October 2011 15.1. HELLO Message Generation A HELLO message is generated as defined in [RFC6130], extended by the following elements being added to the HELLO message by this specification before the HELLO message is sent over an OLSRv2 interface: o A message originator address, recording this router's originator address. This MUST use a element, unless: * The message specifies only a single local interface address (i.e., contains only one address object that is associated with an Address Block TLV with Type = LOCAL_IF, and which has no prefix length, or a maximum prefix length) which will then be interpreted as the message originator address, OR; * The message does not include any local interface network addresses (i.e., has no address objects associated with an Address Block TLV with Type = LOCAL_IF), as permitted by the specification in [RFC6130] when the router that generated the HELLO message has only one interface address and will use that as the sending address of the IP datagram in which the HELLO message is contained. In this case that address will be interpreted as the message originator address. o A Message TLV with Type := MPR_WILLING MUST be included, unless both willingness values that it reports are equal to WILL_DEFAULT (in which case it MAY be included). o The following cases associate Address Block TLVs with one or more addresses from a Link Tuple or a Neighbor Tuple if these are included in the HELLO message. In each case the TLV MUST be associated with at least copy of one address from the relevant Tuple; the TLV MAY be associated with more such addresses (including a copy of that address object, possibly not itself associated with any other indicated TLVs, in the same or a different Address Block). These additional TLVs MUST NOT be associated with any other addresses in a HELLO message that will be processed by [RFC6130]. * For each Link Tuple for which L_in_metric != UNKNOWN_METRIC, and for which one or more addresses in its L_neighbor_iface_addr_list are included as address objects with an associated Address Block TLV with Type = LINK_STATUS and Value = HEARD or Value = SYMMETRIC, at least one of these addresses MUST be associated with an Address Block TLV with Type := LINK_METRIC indicating an incoming link metric with value L_in_metric, unless this equals DEFAULT_METRIC. Clausen, et al. Expires April 16, 2012 [Page 47] Internet-Draft OLSRv2 October 2011 * For each Link Tuple for which L_out_metric != UNKNOWN_METRIC, and for which one or more addresses in its L_neighbor_iface_addr_list are included as address objects with an associated Address Block TLV with Type = LINK_STATUS and Value = SYMMETRIC, at least one of these addresses MUST be associated with an Address Block TLV with Type := LINK_METRIC indicating an outgoing link metric with value L_out_metric, unless this equals DEFAULT_METRIC. * For each Neighbor Tuple for which N_symmetric = true, and for which one or more addresses in its N_neighbor_addr_list are included as address objects with an associated Address Block TLV with Type = LINK_STATUS or Type = OTHER_NEIGHB and Value = SYMMETRIC, at least one of these addresses MUST be associated with an Address Block TLV with Type := LINK_METRIC indicating an incoming neighbor metric with value N_in_metric, unless this equals DEFAULT_METRIC. * For each Neighbor Tuple for which N_symmetric = true, and for which one or more addresses in its N_neighbor_addr_list are included as address objects with an associated Address Block TLV with Type = LINK_STATUS or Type = OTHER_NEIGHB and Value = SYMMETRIC, at least one of these addresses MUST be associated with an Address Block TLV with Type := LINK_METRIC indicating an outgoing neighbor metric with value N_out_metric, unless this equals DEFAULT_METRIC. * For each Neighbor Tuple with N_flooding_mpr = true, and for which one or more network addresses in its N_neighbor_addr_list are included as address objects in the HELLO message with an associated Address Block TLV with Type = LINK_STATUS and Value = SYMMETRIC, at least one of these addresses MUST be associated with an Address Block TLV with Type := MPR and Value := FLOODING or Value := FLOOD_ROUTE. * For each Neighbor Tuple with N_routing_mpr = true, and for which one or more network addresses in its N_neighbor_addr_list are included as address objects in the HELLO message with an associated Address Block TLV with Type = LINK_STATUS and Value = SYMMETRIC, at least one of these addresses MUST be associated with an Address Block TLV with Type := MPR and Value := ROUTING or Value := FLOOD_ROUTE. 15.2. HELLO Message Transmission HELLO messages are scheduled and transmitted by [RFC6130]. This protocol MAY require that an additional HELLO message is sent when either of the router's sets of MPRs changes, in addition to the cases Clausen, et al. Expires April 16, 2012 [Page 48] Internet-Draft OLSRv2 October 2011 specified in [RFC6130], and subject to the same constraints. 15.3. HELLO Message Processing When received on an OLSRv2 interface, HELLO messages are made available to this protocol in two ways, both as permitted by [RFC6130]: o Such received HELLO messages MUST be made available to this protocol on reception, which allows them to be discarded before being processed by [RFC6130], for example if the information added to the HELLO message by this specification is inconsistent. o Such received HELLO messages MUST be made available to OLSRv2 after [RFC6130] has completed its processing thereof, unless discarded as malformed by [RFC6130], for processing by this specification. 15.3.1. HELLO Message Discarding In addition to the reasons specified in [RFC6130] for discarding a HELLO message on reception, a HELLO message MUST be discarded before processing by [RFC6130] or this specification if it: o Has more than one Message TLV with Type = MPR_WILLING. o Has a message originator address, or a network address corresponding to an address object associated with an Address Block TLV with Type = LOCAL_IF, that is partially owned by this router. (Some of these cases are already excluded by [RFC6130].) o Includes any address object associated with an Address Block TLV with Type = LINK_STATUS or Type = OTHER_NEIGHB that overlaps the message's originator address. o Contains any address that will be processed by [RFC6130] that is associated, using the same or different address objects, with two different values of link metric with the same kind and direction using a TLV with Type = LINK_METRIC and Type Extension = LINK_METRIC_TYPE. This also applies to different addresses that are both of the OLSRv2 interface on which the HELLO message was received. o Contains any address object associated with an Address Block TLV with Type = MPR that is not also associated with an Address Block TLV with Type = LINK_STATUS and Value = SYMMETRIC (including using a different copy of that address object, in the same or a different Address Block). Clausen, et al. Expires April 16, 2012 [Page 49] Internet-Draft OLSRv2 October 2011 15.3.2. HELLO Message Usage HELLO messages are first processed as specified in [RFC6130]. That processing includes identifying (or creating) a Link Tuple and a Neighbor Tuple corresponding to the originator of the HELLO message (the "current Link Tuple" and the "current Neighbor Tuple"). After this, the following processing MUST also be performed: 1. If the HELLO message has a well-defined message originator address, i.e., has an element or has zero or one network addresses associated with a TLV with Type = LOCAL_IF: 1. Remove any Neighbor Tuple, other than the current Neighbor Tuple, with N_orig_addr = message originator address, taking any consequent action (including removing one or more Link Tuples) as specified in [RFC6130]. 2. The current Link Tuple is then updated according to: 1. Update L_in_metric and L_out_metric as described in Section 15.3.2.1; 2. Update L_mpr_selector as described in Section 15.3.2.3. 3. The current Neighbor Tuple is then updated according to: 1. N_orig_addr := message originator address; 2. Update N_in_metric and N_out_metric as described in Section 15.3.2.1; 3. Update N_will_flooding and N_will_routing as described in Section 15.3.2.2; 4. Update N_mpr_selector as described in Section 15.3.2.3. 2. If there are any changes to the router's Information Bases, then perform the processing defined in Section 17. 15.3.2.1. Updating Metrics For each address in a received HELLO message with an associated TLV with Type = LINK_STATUS and Value = HEARD or Value = SYMMETRIC, an incoming (to the message originator) link metric value is defined either using an associated TLV with Type = LINK_METRIC and Type Extension = LINK_METRIC_TYPE that indicates the appropriate kind (link) and direction (incoming) of metric, or as the value DEFAULT_METRIC. Clausen, et al. Expires April 16, 2012 [Page 50] Internet-Draft OLSRv2 October 2011 For each address in a received HELLO message with an associated TLV with Type = LINK_STATUS and Value = SYMMETRIC, an outgoing (to the message originator) link metric value is defined either using an associated TLV with Type = LINK_METRIC and Type Extension = LINK_METRIC_TYPE that indicates the appropriate kind (link) and direction (outgoing) of metric, or as the value DEFAULT_METRIC. For each address in a received HELLO message with an associated TLV with Type = LINK_STATUS or Type = OTHER_NEIGHB and Value = SYMMETRIC, an incoming (to the message originator) neighbor metric value is defined either using an associated TLV with Type = LINK_METRIC and Type Extension = LINK_METRIC_TYPE that indicates the appropriate kind (neighbor) and direction (incoming) of metric, or as the value DEFAULT_METRIC. For each address in a received HELLO message with an associated TLV with Type = LINK_STATUS or Type = OTHER_NEIGHB and Value = SYMMETRIC, an outgoing (to the message originator) neighbor metric value is defined either using an associated TLV with Type = LINK_METRIC and Type Extension = LINK_METRIC_TYPE that indicates the appropriate kind (neighbor) and direction (outgoing) of metric, or as the value DEFAULT_METRIC. The link metric elements L_in_metric and L_out_metric in a Link Tuple are updated according to the following: o For any Link Tuple, L_in_metric MAY be set to any representable value, by a process outside this specification, at any time. L_in_metric MUST be so set whenever L_status becomes equal to HEARD or SYMMETRIC (if no other value is available then the value MAXIMUM_METRIC SHOULD be used). This MAY use information based on the receipt of a packet including a HELLO message that causes the creation or updating of that Link Tuple. o When, as specified in [RFC6130], a Link Tuple is updated (possibly immediately after being created) due to the receipt of a HELLO message, if L_status = SYMMETRIC, then L_out_metric is set equal to the incoming link metric for any included address of the interface on which the HELLO message was received, ignoring any values equal to DEFAULT_METRIC unless there are only such values. (Note that the rules for discarding HELLO messages in Section 15.3.1 make this value unambiguous.) The neighbor metric elements N_in_metric and N_out_metric in a Neighbor Tuple are updated according to Section 17.3. The metric elements N2_in_metric and N2_out_metric in any 2-Hop Tuple updated as defined in [RFC6130] are updated to equal the incoming Clausen, et al. Expires April 16, 2012 [Page 51] Internet-Draft OLSRv2 October 2011 neighbor metric and outgoing neighbor metric, respectively, associated with the corresponding N2_2hop_addr. 15.3.2.2. Updating Willingness N_will_flooding and N_will_routing in the current Neighbor Tuple are updated as follows: 1. If the HELLO message contains a Message TLV with Type = MPR_WILLING then N_will_flooding := bits 0-3 of the value of that TLV, and N_will_routing := bits 4-7 of the value of that TLV (each in the range 0 to 15). 2. Otherwise, N_will_flooding := WILL_DEFAULT, and N_will_routing := WILL_DEFAULT. 15.3.2.3. Updating MPR Selector Status L_mpr_selector is updated as follows: 1. If a router finds an address object representing any of its local interface network addresses (i.e., those contained in the I_local_iface_addr_list of an OLSRv2 interface) with an associated Address Block TLV with Type = MPR and Value = FLOODING or Value = FLOOD_ROUTE in the HELLO message (indicating that the originating router has selected the receiving router as a flooding MPR) then, for the current Link Tuple: * L_mpr_selector := true. 2. Otherwise (i.e., if no such address object and Address Block TLV was found) if a router finds an address object representing any of its local interface network addresses (i.e., those contained in the I_local_iface_addr_list of an OLSRv2 interface) with an associated Address Block TLV with Type = LINK_STATUS and Value = SYMMETRIC in the HELLO message, then for the current Link Tuple: * L_mpr_selector := false. N_mpr_selector is updated as follows: 1. If a router finds an address object representing any of its local interface network addresses (i.e., those contained in the I_local_iface_addr_list of an OLSRv2 interface) with an associated Address Block TLV with Type = MPR and Value = ROUTING or Value = FLOOD_ROUTE in the HELLO message (indicating that the originating router has selected the receiving router as a routing MPR) then, for the current Neighbor Tuple: Clausen, et al. Expires April 16, 2012 [Page 52] Internet-Draft OLSRv2 October 2011 * N_mpr_selector := true; * N_advertised := true. 2. Otherwise (i.e., if no such address object and Address Block TLV was found) if a router finds an address object representing any of its local interface network addresses (i.e., those contained in the I_local_iface_addr_list of an OLSRv2 interface) with an associated Address Block TLV with Type = LINK_STATUS and Value = SYMMETRIC in the HELLO message, then for the current Neighbor Tuple: * N_mpr_selector := false; * The router MAY also set N_advertised := false. 16. TC Messages This protocol defines, and hence owns, the TC message type (see Section 24). Thus, as specified in [RFC5444], this protocol generates and transmits all TC messages, receives all TC messages and is responsible for determining whether and how each TC message is to be processed (updating the Topology Information Base) and/or forwarded, according to this specification. 16.1. TC Message Generation A TC message is a message as defined in [RFC5444]. A generated TC message MUST contain the following elements as defined in [RFC5444]: o A message originator address, recording this router's originator address. This MUST use a element. o element containing the message sequence number. o A element, containing TC_HOP_LIMIT. A router MAY use the same or different values of TC_HOP_LIMIT in its TC messages, see Section 5.4.7. o A element, containing zero, if the message contains a TLV with either Type = VALIDITY_TIME or Type = INTERVAL_TIME (as specified in [RFC5497]) indicating more than one time value according to distance. A TC message MAY contain such a element even if it does not need to. o A single Message TLV with Type := CONT_SEQ_NUM and Value := ANSN from the Neighbor Information Base. If the TC message is complete then this Message TLV MUST have Type Extension := COMPLETE, Clausen, et al. Expires April 16, 2012 [Page 53] Internet-Draft OLSRv2 October 2011 otherwise it MUST have Type Extension := INCOMPLETE. (Exception: a TC message MAY omit such a Message TLV if the TC message does not include any address objects with an associated Address Block TLV with Type = NBR_ADDR_TYPE or Type = GATEWAY.) o A single Message TLV with Type := VALIDITY_TIME, as specified in [RFC5497]. If all TC messages are sent with the same hop limit then this TLV MUST have a value encoding the period T_HOLD_TIME. If TC messages are sent with different hop limits (more than one value of TC_HOP_LIMIT) then this TLV MUST specify times that vary with the number of hops distance appropriate to the chosen pattern of TC message hop limits, as specified in [RFC5497]; these times SHOULD be appropriate multiples of T_HOLD_TIME. The options included in [RFC5497] for representing zero and infinite times MUST NOT be used. o If the TC message is complete, all network addresses which are the N_orig_addr of a Neighbor Tuple with N_advertised = true, MUST be represented by address objects in one or more Address Blocks. If the TC message is incomplete then any such address objects MAY be included. At least one copy of each such address object that is included MUST be associated with an Address Block TLV with Type := NBR_ADDR_TYPE, and Value := ORIGINATOR, or with Value := ROUTABLE_ORIG if that address object is also to be associated with Value = ROUTABLE. o If the TC message is complete, all routable addresses which are in the N_neighbor_addr_list of a Neighbor Tuple with N_advertised = true MUST be represented by address objects in one or more Address Blocks. If the TC message is incomplete then any such address objects MAY be included. At least one copy of each such address object MUST be associated with an Address Block TLV with Type = NBR_ADDR_TYPE, and Value = ROUTABLE, or with Value = ROUTABLE_ORIG if also to be associated with Value = ORIGINATOR. At least one copy of each such address object MUST be associated with an Address Block TLV with Type = LINK_METRIC and Type Extension = LINK_METRIC_TYPE indicating an outgoing neighbor metric with value equal to the corresponding N_out_metric, unless that value is DEFAULT_METRIC. o If the TC message is complete, all network addresses which are the AL_net_addr of a Local Attached Network Tuple MUST be represented by address objects in one or more Address Blocks. If the TC message is incomplete then any such address objects MAY be included. At least one copy of each such address object MUST be associated with an Address Block TLV with Type := GATEWAY, and Value := AN_dist. At least one copy of each such address object MUST be associated with an Address Block TLV with Type = Clausen, et al. Expires April 16, 2012 [Page 54] Internet-Draft OLSRv2 October 2011 LINK_METRIC and Type Extension = LINK_METRIC_TYPE indicating an outgoing neighbor metric equal to the corresponding AL_metric, unless that value is DEFAULT_METRIC. A TC message MAY contain: o A single Message TLV with Type := INTERVAL_TIME, as specified in [RFC5497]. If all TC messages are sent with the same hop limit then this TLV MUST have a value encoding the period TC_INTERVAL. If TC messages are sent with different hop limits, then this TLV MUST specify times that vary with the number of hops distance appropriate to the chosen pattern of TC message hop limits, as specified in [RFC5497]; these times SHOULD be appropriate multiples of TC_INTERVAL. The options included in [RFC5497] for representing zero and infinite times MUST NOT be used. 16.2. TC Message Transmission A router with one or more OLSRv2 interfaces, and with any Neighbor Tuples with N_advertised = true, or with a non-empty Local Attached Network Set MUST generate TC messages. A router which does not have such information to advertise SHOULD also generate "empty" TC messages for a period A_HOLD_TIME after it last generated a non-empty TC message. Complete TC messages are generated and transmitted periodically on all OLSRv2 interfaces, with a default interval between two consecutive TC message transmissions by the same router of TC_INTERVAL. TC messages MAY be generated in response to a change in the information which they are to advertise, indicated by a change in the ANSN in the Neighbor Information Base. In this case a router MAY send a complete TC message, and if so MAY re-start its TC message schedule. Alternatively a router MAY send an incomplete TC message with at least the newly advertised network addresses (i.e., not previously, but now, an N_orig_addr or in an N_neighbor_addr_list in a Neighbor Tuple with N_advertised = true, or an AL_net_addr) in its Address Blocks, with associated Address Block TLV(s). Note that a router cannot report removal of advertised content using an incomplete TC message. When sending a TC message in response to a change of advertised network addresses, a router MUST respect a minimum interval of TC_MIN_INTERVAL between generated TC messages. Sending an incomplete TC message MUST NOT cause the interval between complete TC messages to be increased, and thus a router MUST NOT send an incomplete TC message if within TC_MIN_INTERVAL of the next scheduled complete TC Clausen, et al. Expires April 16, 2012 [Page 55] Internet-Draft OLSRv2 October 2011 message. The generation of TC messages, whether scheduled or triggered by a change of contents, MAY be jittered as described in [RFC5148]. The values of MAXJITTER used SHOULD be: o TP_MAXJITTER for periodic TC message generation; o TT_MAXJITTER for responsive TC message generation. 16.3. TC Message Processing On receiving a TC message, the receiving router MUST then follow the processing and forwarding procedure, defined in Section 14. If the message is considered for processing (Section 14.2), then a router MUST first check if the message is invalid for processing by this router, as defined in Section 16.3.1. A router MAY make a similar check before considering a message for forwarding, it MUST make those aspects of the check that apply to elements in the Message Header. If the TC message is not invalid, then the TC message type specific processing, described in Section 16.3.2 MUST be applied. This will update its appropriate Interface Information Base and its Router Information Base. Following this, if there are any changes in these Information Bases, then the processing in Section 17 MUST be performed. 16.3.1. Invalid Message A received TC message is invalid for processing by this router if the message: o Has an address length specified in the Message Header that is not equal to the length of the addresses used by this router. o Does not include a message originator address and a message sequence number. o Does not include a hop count, and contains a multi-value TLV with Type = VALIDITY_TIME or Type = INTERVAL_TIME, as defined in [RFC5497]. o Does not have exactly one Message TLV with Type = VALIDITY_TIME. o Has more than one Message TLV with Type = INTERVAL_TIME. Clausen, et al. Expires April 16, 2012 [Page 56] Internet-Draft OLSRv2 October 2011 o Does not have a Message TLV with Type = CONT_SEQ_NUM and Type Extension = COMPLETE or Type Extension = INCOMPLETE, and contains at least one address object associated with an Address Block TLV with Type = NBR_ADDR_TYPE or Type = GATEWAY. o Has more than one Message TLV with Type = CONT_SEQ_NUM and Type Extension = COMPLETE or Type Extension = INCOMPLETE. o Has a message originator address that is partially owned by this router. o Includes any address object with a prefix length which is not maximal (equal to the address length, in bits), associated with an Address Block TLV with Type = NBR_ADDR_TYPE and Value = ORIGINATOR or Value = ROUTABLE_ORIG. o Includes any address object that represents a non-routable address, associated with an Address Block TLV with Type = NBR_ADDR_TYPE and Value = ROUTABLE or Value = ROUTABLE_ORIG. o Includes any address object associated with an Address Block TLV with Type = NBR_ADDR_TYPE or Type = GATEWAY that also represents the message's originator address. o Includes any address object (including different copies of an address object, in the same or different Address Blocks) that is associated with an Address Block TLV with Type = NBR_ADDR_TYPE or Type = GATEWAY, that is also associated with more than one outgoing neighbor metric using a TLV with Type = LINK_METRIC and Type Extension = LINK_METRIC_TYPE. o Associates any address object (including different copies of an address object, in the same or different Address Blocks) with more than one single hop count value using one or more Address Block TLV(s) with Type = GATEWAY. o Associates any address object (including different copies of an address object, in the same or different Address Blocks) with Address Block TLVs with Type = NBR_ADDR_TYPE and Type = GATEWAY. A router MAY recognize additional reasons for identifying that a message is invalid. An invalid message MUST be silently discarded, without updating the router's Information Bases. 16.3.2. TC Message Processing Definitions When, according to Section 14.2, a TC message is to be "processed according to its type", this means that: Clausen, et al. Expires April 16, 2012 [Page 57] Internet-Draft OLSRv2 October 2011 o If the TC message contains a Message TLV with Type = CONT_SEQ_NUM and Type Extension = COMPLETE, then processing according to Section 16.3.3 and then according to Section 16.3.4 is carried out. o If the TC message contains a Message TLV with Type = CONT_SEQ_NUM and Type Extension = INCOMPLETE, then only processing according to Section 16.3.3 is carried out. For the purposes of this section: o "validity time" is calculated from a VALIDITY_TIME Message TLV in the TC message according to the specification in [RFC5497]. All information in the TC message has the same validity time. o "received ANSN" is defined as being the value of a Message TLV with Type = CONT_SEQ_NUM. o "associated metric value" is defined for any address in the TC message as being either the outgoing neighbor metric value indicated by a TLV with Type = LINK_METRIC and Type Extension = LINK_METRIC_TYPE that is associated with any address object in the TC message that is equal to that address, or as DEFAULT_METRIC otherwise. (Note that the rules in Section 16.3.1 make this definition unambiguous.) o Comparisons of sequence numbers are carried out as specified in Section 21. 16.3.3. Initial TC Message Processing The TC message is processed as follows: 1. The Advertising Remote Router Set is updated according to Section 16.3.3.1. If the TC message is indicated as discarded in that processing then the following steps are not carried out. 2. The Router Topology Set is updated according to Section 16.3.3.2. 3. The Routable Address Topology Set is updated according to Section 16.3.3.3. 4. The Attached Network Set is updated according to Section 16.3.3.4. Clausen, et al. Expires April 16, 2012 [Page 58] Internet-Draft OLSRv2 October 2011 16.3.3.1. Populating the Advertising Remote Router Set The router MUST update its Advertising Remote Router Set as follows: 1. If there is an Advertising Remote Router Tuple with: * AR_orig_addr = message originator address, AND; * AR_seq_number > received ANSN, then the TC message MUST be discarded. 2. Otherwise: 1. If there is no Advertising Remote Router Tuple such that: + AR_orig_addr = message originator address; then create an Advertising Remote Router Tuple with: + AR_orig_addr := message originator address. 2. This Advertising Remote Router Tuple (existing or new) is then modified as follows: + AR_seq_number := received ANSN; + AR_time := current time + validity time. 16.3.3.2. Populating the Router Topology Set The router MUST update its Router Topology Set as follows: 1. For each address (henceforth advertised address) corresponding to one or more address objects with an associated Address Block TLV with Type = NBR_ADDR_TYPE and Value = ORIGINATOR or Value = ROUTABLE_ORIG, and that is not partially owned by this router, perform the following processing: 1. If there is no Router Topology Tuple such that: + TR_from_orig_addr = message originator address, AND; + TR_to_orig_addr = advertised address, then create a new Router Topology Tuple with: Clausen, et al. Expires April 16, 2012 [Page 59] Internet-Draft OLSRv2 October 2011 + TR_from_orig_addr := message originator address; + TR_to_orig_addr := advertised address. 2. This Router Topology Tuple (existing or new) is then modified as follows: + TR_seq_number := received ANSN; + TR_metric := associated link metric; + TR_time := current time + validity time. 16.3.3.3. Populating the Routable Address Topology Set The router MUST update its Routable Address Topology Set as follows: 1. For each network address (henceforth advertised address) corresponding to one or more address objects with an associated Address Block TLV with Type = NBR_ADDR_TYPE and Value = ROUTABLE or Value = ROUTABLE_ORIG, and that is not partially owned by this router, perform the following processing: 1. If there is no Routable Address Topology Tuple such that: + TA_from_orig_addr = message originator address, AND; + TA_dest_addr = advertised address, then create a new Routable Address Topology Tuple with: + TA_from_orig_addr := message originator address; + TA_dest_addr := advertised address. 2. This Routable Address Topology Tuple (existing or new) is then modified as follows: + TA_seq_number := received ANSN; + TA_metric := associated link metric; + TA_time := current time + validity time. Clausen, et al. Expires April 16, 2012 [Page 60] Internet-Draft OLSRv2 October 2011 16.3.3.4. Populating the Attached Network Set The router MUST update its Attached Network Set as follows: 1. For each network address (henceforth attached address) corresponding to one or more address objects with an associated Address Block TLV with Type = GATEWAY, and that is not fully owned by this router, perform the following processing: 1. If there is no Attached Network Tuple such that: + AN_net_addr = attached address, AND; + AN_orig_addr = message originator address, then create a new Attached Network Tuple with: + AN_net_addr := attached address; + AN_orig_addr := message originator address. 2. This Attached Network Tuple (existing or new) is then modified as follows: + AN_seq_number := received ANSN; + AN_dist := the Value of the associated GATEWAY TLV; + AN_metric := associated link metric; + AN_time := current time + validity time. 16.3.4. Completing TC Message Processing The TC message is processed as follows: 1. The Router Topology Set is updated according to Section 16.3.4.1. 2. The Routable Address Topology Set is updated according to Section 16.3.4.2. 3. The Attached Network Set is updated according to Section 16.3.4.3. Clausen, et al. Expires April 16, 2012 [Page 61] Internet-Draft OLSRv2 October 2011 16.3.4.1. Purging the Router Topology Set The Router Topology Set MUST be updated as follows: 1. Any Router Topology Tuples with: * TR_from_orig_addr = message originator address, AND; * TR_seq_number < received ANSN, MUST be removed. 16.3.4.2. Purging the Routable Address Topology Set The Routable Address Topology Set MUST be updated as follows: 1. Any Routable Address Topology Tuples with: * TA_from_orig_addr = message originator address, AND; * TA_seq_number < received ANSN, MUST be removed. 16.3.4.3. Purging the Attached Network Set The Attached Network Set MUST be updated as follows: 1. Any Attached Network Tuples with: * AN_orig_addr = message originator address, AND; * AN_seq_number < received ANSN, MUST be removed. 17. Information Base Changes The changes described in the following sections MUST be carried out when any Information Base changes as indicated. 17.1. Originator Address Changes If the router changes originator address, then: 1. If there is no Originator Tuple with: Clausen, et al. Expires April 16, 2012 [Page 62] Internet-Draft OLSRv2 October 2011 * O_orig_addr = old originator address then create an Originator Tuple with: * O_orig_addr := old originator address The Originator Tuple (existing or new) with: * O_orig_addr = new originator address is then modified as follows: * O_time := current time + O_HOLD_TIME 17.2. Link State Changes The consistency of a Link Tuple MUST be maintained according to the following rules, in addition to those in [RFC6130]: o If L_status = HEARD or L_status = SYMMETRIC, then L_in_metric MUST be set (by a process outside this specification). o If L_status != SYMMETRIC, then set L_mpr_selector := false. o If L_out_metric = UNKNOWN_METRIC, then L_status MUST NOT equal SYMMETRIC; set L_SYM_time := expired if this would otherwise be the case. 17.3. Neighbor State Changes The consistency of a Neighbor Tuple MUST be maintained according to the following rules, in addition to those in [RFC6130]: 1. If N_symmetric = true, then N_in_metric MUST equal the minimum value of all L_in_metric of corresponding Link Tuples with L_status = SYMMETRIC. 2. If N_symmetric = true, then N_out_metric MUST equal the minimum value of all L_out_metric of corresponding Link Tuples with L_status = SYMMETRIC. 3. If N_symmetric = false, then N_flooding_mpr, N_routing_mpr, N_mpr_selector and N_advertised MUST all be equal to false. 4. If N_mpr_selector = true, then N_advertised MUST be equal to true. Clausen, et al. Expires April 16, 2012 [Page 63] Internet-Draft OLSRv2 October 2011 5. If N_symmetric = true and N_mpr_selector = false, then a router MAY select N_advertised = true or N_advertised = false. The more neighbors that are advertised, the larger TC messages become, but the more redundancy is available for routing. A router SHOULD consider the nature of its network in making such a decision, and SHOULD avoid unnecessary changes in advertising status, which may result both in additional TC messages having to be sent by its neighbors, and in unnecessary changes to routing, which will have similar effects to other forms of topology changes in the MANET. 17.4. Advertised Neighbor Changes The router MUST increment the ANSN in the Neighbor Information Base whenever: 1. Any Neighbor Tuple changes its N_advertised value, or any Neighbor Tuple with N_advertised = true is removed. 2. Any Neighbor Tuple with N_advertised = true changes its N_orig_addr, or has any routable address is added to or removed from N_neighbor_addr_list. 3. Any Neighbor Tuple with N_advertised = true has N_out_metric changed. 4. There is any change to the Local Attached Network Set. 17.5. Advertising Remote Router Tuple Expires The Router Topology Set, the Routable Address Topology Set and the Attached Network Set MUST be changed when an Advertising Remote Router Tuple expires (AR_time is reached). The following changes are required before the Advertising Remote Router Tuple is removed: 1. All Router Topology Tuples with: * TR_from_orig_addr = AR_orig_addr of the Advertising Remote Router Tuple are removed. 2. All Routable Address Topology Tuples with: * TA_from_orig_addr = AR_orig_addr of the Advertising Remote Router Tuple are removed. Clausen, et al. Expires April 16, 2012 [Page 64] Internet-Draft OLSRv2 October 2011 3. All Attached Network Tuples with: * AN_orig_addr = AR_orig_addr of the Advertising Remote Router Tuple are removed. 17.6. Neighborhood Changes and MPR Updates The sets of symmetric 1-hop neighbors selected as flooding MPRs and routing MPRs MUST satisfy the conditions defined in Section 18. To ensure this: 1. The set of flooding MPRs of a router MUST be recalculated if: * a Link Tuple is added with L_status = SYMMETRIC, OR; * a Link Tuple with L_status = SYMMETRIC is removed, OR; * a Link Tuple with L_status = SYMMETRIC changes to having L_status = HEARD or L_status = LOST, OR; * a Link Tuple with L_status = HEARD or L_status = LOST changes to having L_status = SYMMETRIC, OR; * the flooding MPR selection process uses metrics (see Section 18.4 and the L_out_metric of any Link Tuple with L_status = SYMMETRIC changes, OR; * a 2-Hop Tuple is added or removed, OR; * the N_will_flooding of a Neighbor Tuple with N_symmetric = true changes from WILL_NEVER to any other value, OR; * the N_will_flooding of a Neighbor Tuple with N_flooding_mpr = true changes to WILL_NEVER from any other value, OR; * the N_will_flooding of a Neighbor Tuple with N_symmetric = true and N_flooding_mpr = false changes to WILL_ALWAYS from any other value, OR; * the flooding MPR selection process uses metrics (see Section 18.4 and the N2_out_metric of any 2-Hop Tuple changes. 2. Otherwise, the set of flooding MPRs of a router MAY be recalculated if the N_will_flooding of a Neighbor Tuple with N_symmetric = true changes in any other way; it SHOULD be recalculated if N_flooding_mpr = false and this is an increase in Clausen, et al. Expires April 16, 2012 [Page 65] Internet-Draft OLSRv2 October 2011 N_will_flooding or if N_flooding_mpr = true and this is a decrease in N_will_flooding. 3. The set of routing MPRs of a router MUST be recalculated if: * a Link Tuple is added with L_status = SYMMETRIC, OR; * a Link Tuple with L_status = SYMMETRIC is removed, OR; * a Link Tuple with L_status = SYMMETRIC changes to having L_status = HEARD or L_status = LOST, OR; * a Link Tuple with L_status = HEARD or L_status = LOST changes to having L_status = SYMMETRIC, OR; * a 2-Hop Tuple is added or removed, OR; * the N_will_routing of a Neighbor Tuple with N_symmetric = true changes from WILL_NEVER to any other value, OR; * the N_will_routing of a Neighbor Tuple with N_routing_mpr = true changes to WILL_NEVER from any other value, OR; * the N_will_routing of a Neighbor Tuple with N_symmetric = true and N_routing_mpr = false changes to WILL_ALWAYS from any other value, OR; * the N_in_metric of any Neighbor Tuple with N_symmetric changes, OR; * the N2_in_metric of any 2-Hop Tuple changes. 4. Otherwise, the set of routing MPRs of a router MAY be recalculated if the N_will_routing of a Neighbor Tuple with N_symmetric = true changes in any other way; it SHOULD be recalculated if N_routing_mpr = false and this is an increase in N_will_routing or if N_routing_mpr = true and this is a decrease in N_will_routing. If either set of MPRs of a router is recalculated, this MUST be as described in Section 18. 17.7. Routing Set Updates The Routing Set MUST be updated, as described in Section 19, when changes in the Local Information Base, the Neighborhood Information Base or the Topology Information Base indicate a change (including of any potentially used outgoing neighbor metric values) of the known Clausen, et al. Expires April 16, 2012 [Page 66] Internet-Draft OLSRv2 October 2011 symmetric links and/or attached networks in the MANET, hence changing the Topology Graph. It is sufficient to consider only changes which affect at least one of: o The Local Interface Set, if the change removes any network address in an I_local_iface_addr_list. In this case, unless the OLSRv2 interface is removed, it may not be necessary to do more than replace such network addresses, if used, by an alternative network address from the same I_local_iface_addr_list. o The Local Attached Set, if the change removes any AL_net_addr which is also an AN_net_addr. In this case it may not be necessary to do more than add Routing Tuples with R_dest_addr equal to that AN_net_addr. o The Link Set of any OLSRv2 interface, considering only Link Tuples which have, or just had, L_status = SYMMETRIC (including removal of such Link Tuples). o The Neighbor Set of the router, considering only Neighbor Tuples that have, or just had, N_symmetric = true, and do not have N_orig_addr = unknown. o The 2-Hop Set of any OLSRv2 interface, if used in the creation of the Routing Set. o The Router Topology Set of the router. o The Routable Address Topology Set of the router. o The Attached Network Set of the router. 18. Selecting MPRs Each router MUST select, from among its willing symmetric 1-hop neighbors, two subsets of these routers, as flooding and routing MPRs. This selection is recorded in the router's Neighbor Set, and reported in the router's HELLO messages. Routers MAY select their MPRs by any process that satisfies the conditions which follow, which may, but need not, use the organization of the data described. Routers can freely interoperate whether they use the same or different MPR selection algorithms. Only flooding MPRs forward control messages flooded through the MANET, thus effecting a flooding reduction, an optimization of the flooding mechanism, known as MPR flooding. Routing MPRs are used to effect a topology reduction in the MANET. (If no such reduction is required then a router can select all of its relevant neighbors as Clausen, et al. Expires April 16, 2012 [Page 67] Internet-Draft OLSRv2 October 2011 routing MPRs.) Consequently, while it is not essential that these two sets of MPRs are minimal, keeping the numbers of MPRs small ensures that the overhead of this protocol is kept to a minimum. 18.1. Overview MPRs are selected according to the following steps, defined in the following sections: o A form of data structure known as a Neighbor Graph is defined. o The properties of an MPR Set derived from a Neighbor Graph are defined. Any algorithm that creates an MPR Set that satisfies these properties is a valid MPR selection algorithm. An example algorithm that creates such an MPR Set is given in Appendix A. o How to create a Neighbor Graph for each interface based on the corresponding Interface Information Base is defined, and how to combine the resulting MPR Sets to determine the router's flooding MPRs and record those in the router's Neighbor Set. o How to create a single Neighbor Graph based on all Interface Information Bases and the Neighbor Information Base is defined, and how to record the resulting MPR Set as the router's routing MPRs in the router's Neighbor Set. o A specification as to when MPRs MUST be calculated is given. When a router selects its MPRs it MAY consider any other characteristics of its neighbors that it is aware of. In particular it SHOULD consider the willingness of the neighbor, as recorded by the corresponding N_will_flooding or N_will_routing value, as appropriate, preferring neighbors with higher values. (Note that willingness values equal to WILL_NEVER and WILL_ALWAYS are always considered, as described.) However a router MAY consider other characteristics to have a greater significance. Each router MAY select its flooding and routing MPRs independently from each other, or coordinate its selections. A router MAY make its MPR selections independently of the MPR selection by other routers, or it MAY, for example, give preference to routers that either are, or are not, already selected as MPRs by other routers. 18.2. Neighbor Graph A Neighbor Graph is a structure defined here as consisting of sets N1 and N2 and some associated metric and willingness values. Elements of set N1 represent willing symmetric 1-hop neighbors, and elements Clausen, et al. Expires April 16, 2012 [Page 68] Internet-Draft OLSRv2 October 2011 of set N2 represent addresses of a symmetric 2-hop neighbor. A Neighbor Graph has the following properties: o It contains two disjoint sets N1 and N2. o For each element x in N1 there is an associated willingness value W(x) such that WILL_NEVER < W(x) <= WILL_ALWAYS. o For each element x in N1 there is an associated metric d1(x) > 0. o For some elements y in N2 there is an associated metric d1(y) > 0. (Other elements y in N2 have undefined d1(y), this may be considered to be infinite.) o For each element x in N1 there is a subset N2(x) of elements of N2; this subset may be empty. For each x in N1 and each y in N2(x) there is an associated metric d2(x,y) > 0. (For other x in N1 and y in N2, d2(x,y) is undefined, and may be considered infinite.) o N2 is equal to the union of all the N2(x) for all x in N1, i.e. for each y in N2 there is at least one x in N1 such that y is in N2(x). It is convenient to also define: o For each y in N2 the set N1(y) that contains x in N1 if and only if y is in N2(x). From the final property above, N1(y) is not empty. o For each x in N1 and y in N2, if d2(x,y) is defined then d(x,y) := d1(x)+d2(x,y), otherwise d(x,y) is not defined. (Thus d(x,y) is defined if y is in N2(x), or equivalently if x is in N1(y).) o For any subset S of N1, and for each y in N2, the metric d(y,S) is the minimum value of d1(y), if defined, and of all d(x,y) for x in N1(y) and in S. If there are no such metrics to take the minimum value of, then d(y,S) is undefined (may be considered to be infinite). From the final property above, d(y,N1) is defined for all y. 18.3. MPR Properties Given a Neighbor Graph as defined in Section 18.2. an MPR Set for that Neighbor Graph is a subset M of the set N1 that satisfies the following properties: Clausen, et al. Expires April 16, 2012 [Page 69] Internet-Draft OLSRv2 October 2011 o If x in N1 has W(x) = WILL_ALWAYS then x is in M. o For any y in N2 that does not have a defined d1(y), there is at least one element in M that is also in N1(y). This is equivalent to the requirement that d(y,M) is defined. o For any y in N2, d(y,M) = d(y,N1). These two properties correspond first to that the MPR Set consists of a set of symmetric 1-hop neighbors that cover all the symmetric 2-hop neighbors, and second that they do so retaining a minimum distance route (1-hop, if present, or 2-hop) to each symmetric 2-hop neighbor. Note that if M is an MPR Set, then so is any subset of N1 that contains M, and also that N1 is always an MPR Set. An MPR Set may be empty, but cannot be empty if N2 contains any elements y that do not have a defined d1(y). 18.4. Flooding MPRs Whenever flooding MPRs are to be calculated, an implementation MUST determine and record a set of flooding MPRs that is equivalent to one calculated as described in this section. The calculation of flooding MPRs need not use link metrics, or equivalently may use link metrics with a fixed value, here taken to be 1. Routers MAY make individual decisions as to whether to use link metrics for the calculation of flooding MPRs. A router MUST use the same approach to the choice of whether to use link metrics for all links, i.e. in the cases indicated by a or b, the same choice MUST be made in each case. For each OLSRv2 interface (the "current interface") define a Neighbor Graph as defined in Section 18.2 according to the following: o Define a reachable Link Tuple to be a Link Tuple in the Link Set for the current interface with L_status = SYMMETRIC. o Define an allowed Link Tuple to be a reachable Link Tuple whose corresponding Neighbor Tuple has N_will_flooding > WILL_NEVER. o Define an allowed 2-Hop Tuple to be a 2-Hop Tuple in the 2-Hop Set for the current interface for which there is an allowed Link Tuple with L_neighbor_iface_addr_list = N2_neighbor_iface_addr_list. o Define an element of N1 for each allowed Link Tuple. This then defines the corresponding Link Tuple for each element of N1 and the corresponding Neighbor Tuple for each element of N1, being the Clausen, et al. Expires April 16, 2012 [Page 70] Internet-Draft OLSRv2 October 2011 Neighbor Tuple corresponding to that Link Tuple. o For each element x in N1, define W(x) := N_will_flooding of the corresponding Neighbor Tuple. o For each element x in N1, define d1(x) as either: A. L_out_metric of the corresponding Link Tuple, OR; B. 1. o Define an element of N2 for each network address that is the N2_2hop_addr of one or more allowed 2-Hop Tuples. This then defines the corresponding address for each element of N2. o For each element y in N2, if the corresponding address is in the N_neighbor_addr_list of a Neighbor Tuple that corresponds to one or more reachable Link Tuples, then define d1(y) as either: A. the minimum value of the L_out_metric of those Link Tuples, OR; B. 1. Otherwise d1(y) is not defined. In the latter case, where d1(y) : =1, all such y in N2 may instead be removed from N2. o For each element x in N1, define N2(x) as the set of elements y in N2 whose corresponding address is the N2_2hop_addr of an allowed 2-Hop Tuple that has N2_neighbor_iface_addr_list = L_neighbor_iface_addr_list of the Link Tuple corresponding to x. For all such x and y, define d2(x,y) as either: A. N2_out_metric of that 2-Hop Tuple; B. 1. It is up to the implementer to decide how to label each element of N1 or N2. For example an element of N1 may be labeled with one or more addresses from the corresponding L_neighbor_iface_addr_list, or with a pointer or reference to the corresponding Link Tuple. Using these Neighbor Graphs, flooding MPRs are selected and recorded by: o For each OLSRv2 interface, determine an MPR Set as specified in Section 18.3. Clausen, et al. Expires April 16, 2012 [Page 71] Internet-Draft OLSRv2 October 2011 o A Neighbor Tuple represents a flooding MPR and has N_flooding_mpr := true (otherwise N_flooding_mpr := false) if and only if that Neighbor Tuple corresponds to an element in an MPR Set created for any interface as described above. That is, the overall set of flooding MPRs is the union of the sets of flooding MPRs for all OLSRv2 interfaces. A router MAY select its flooding MPRs for each OLSRv2 interface independently, or it MAY coordinate its MPR selections across its OLSRv2 interfaces, as long as the required condition is satisfied for each OLSRv2 interface. One such coordinated approach is to process the OLSRv2 interfaces sequentially, and for each OLSRv2 interface start with flooding MPRs selected (and not removable) if the neighbor has been already selected as an MPR for an OLSRv2 interface that has already been processed. The algorithm specified in Appendix A can be used in this way. 18.5. Routing MPRs Whenever routing MPRs are to be calculated, an implementation MUST determine and record a set of routing MPRs that is equivalent to one calculated as described in this section. Define a single Neighbor Graph as defined in Section 18.2 according to the following: o Define a reachable Neighbor Tuple to be a Neighbor Tuple with N_symmetric = true. o Define an allowed Neighbor Tuple to be a reachable Neighbor Tuple with N_will_routing > WILL_NEVER. o Define an allowed 2-Hop Tuple to be a 2-Hop Tuple in the 2-Hop Set for any OLSRv2 interface for which there is an allowed Neighbor Tuple with N_neighbor_addr_list containing N2_neighbor_iface_addr_list. o Define an element of N1 for each allowed Neighbor Tuple. This then defines the corresponding Neighbor Tuple for each element of N1. o For each element x in N1, define W(x) := N_will_routing of the corresponding Neighbor Tuple. o For each element x in N1, define d1(x) := N_in_metric of the corresponding Neighbor Tuple. Clausen, et al. Expires April 16, 2012 [Page 72] Internet-Draft OLSRv2 October 2011 o Define an element of N2 for each network address that is the N2_2hop_addr of one or more allowed 2-Hop Tuples. This then defines the corresponding address for each element of N2. o For each element y in N2, if the corresponding address is in the N_neighbor_addr_list of a reachable Neighbor Tuple, then define d1(y) to be the N_in_metric of that Neighbor Tuple, otherwise d1(y) is not defined. o For each element x in N1, define N2(x) as the set of elements y in N2 whose corresponding address is the N2_2hop_addr of an allowed 2-Hop Tuple that has N2_neighbor_iface_addr_list contained in N_neighbor_addr_list of the Neighbor Tuple corresponding to x. For all such x and y, define d2(x,y) := N2_out_metric of that 2-Hop Tuple. It is up to the implementer to decide how to label each element of N1 or N2. For example an element of N1 may be labeled with one or more addresses from the corresponding N_neighbor_addr_list, or with a pointer or reference to the corresponding Neighbor Tuple. Using these Neighbor Graphs, routing MPRs are selected and recorded by: o Determine an MPR Set as specified in Section 18.3 o A Neighbor Tuple represents a routing MPR and has N_routing_mpr := true (otherwise N_routing_mpr := false) if and only if that Neighbor Tuple corresponds to an element in the MPR Set created as described above. 18.6. Calculating MPRs A router MUST recalculate each of its sets of MPRs whenever the currently selected set of MPRs does not still satisfy the required conditions. It MAY recalculate its MPRs if the current set of MPRs is still valid, but could be more efficient. Sufficient conditions to recalculate a router's sets of MPRs are given in Section 17.6. 19. Routing Set Calculation The Routing Set of a router is populated with Routing Tuples that represent paths from that router to all destinations in the network. These paths are calculated based on the Network Topology Graph, which is constructed from information in the Information Bases, obtained via HELLO and TC message exchange. Changes to the Routing Set do not require any messages to be Clausen, et al. Expires April 16, 2012 [Page 73] Internet-Draft OLSRv2 October 2011 transmitted. The state of the Routing Set SHOULD, however, be reflected in IP's routing table by adding and removing entries from IP's routing table as appropriate. Only appropriate Routing Tuples (in particular only those that represent local links or paths to routable addresses) need be reflected in IP's routing table. 19.1. Network Topology Graph The Network Topology Graph is formed from information from the router's Local Interface Set, Link Sets, Neighbor Set, Router Topology Set, Routable Address Topology Set and Attached Network Set. The Network Topology Graph MAY also use information from the router's 2-Hop Sets. The Network Topology Graph forms the router's topological view of the network in form of a directed graph. Each edge in that graph has a metric value. The Network Topology Graph has a "backbone" (within which minimum total metric routes will be constructed) containing the following edges: o Edges X -> Y for all possible Y, and one X per Y, such that: * Y is the N_orig_addr of a Neighbor Tuple, AND; * N_orig_addr is not unknown; * X is in the I_local_iface_addr_list of a Local Interface Tuple, AND; * There is a Link Tuple with L_status = SYMMETRIC such that this Neighbor Tuple and this Local Interface Tuple correspond to it. A network address from L_neighbor_iface_addr_list will be denoted R in this case. It SHOULD be preferred, where possible, to select R = S and X from the Local Interface Tuple corresponding to the Link Tuple from which R was selected. The metric such an edge is the corresponding N_out_metric. o All edges W -> U such that: * W is the TR_from_orig_addr of a Router Topology Tuple, AND; * U is the TR_to_orig_addr of the same Router Topology Tuple. The metric of such an edge is the corresponding TR_metric. The Network Topology Graph is further "decorated" with the following edges. If a network address S, V, Z or T equals a network address Y or W, then the edge terminating in the network address S, V, Z or T Clausen, et al. Expires April 16, 2012 [Page 74] Internet-Draft OLSRv2 October 2011 MUST NOT be used in any path. o Edges X -> S for all possible S, and one X per S, such that: * S is in the N_neighbor_addr_list of a Neighbor Tuple, AND; * X is in the I_local_iface_addr_list of a Local Interface Tuple, AND; * There is a Link Tuple with L_status = SYMMETRIC such that this Neighbor Tuple and this Local Interface Tuple correspond to it. A network address from L_neighbor_iface_addr_list will be denoted R in this case. It SHOULD be preferred, where possible, to select R = S and X from the Local Interface Tuple corresponding to the Link Tuple from which R was selected. The metric of such an edge is the corresponding N_out_metric. o All edges W -> V such that: * W is the TA_from_orig_addr of a Routable Address Topology Tuple, AND; * V is the TA_dest_addr of the same Routable Address Topology Tuple. The metric for such an edge is the corresponding TA_metric. o All edges W -> T such that: * W is the AN_orig_addr of an Attached Network Tuple, AND; * T is the AN_net_addr of the same Attached Network Tuple. The metric for such an edge is the corresponding AN_metric. o OPTIONALLY, all edges Y -> Z such that: * Z is a routable address and is the N2_2hop_addr of a 2-Hop Tuple, AND; * Y is the N_orig_addr of the corresponding Neighbor Tuple, AND; * This Neighbor Tuple has N_will_routing not equal to WILL_NEVER. A path terminating with such an edge SHOULD NOT be used in preference to any other path. The metric for such an edge is the Clausen, et al. Expires April 16, 2012 [Page 75] Internet-Draft OLSRv2 October 2011 corresponding N2_out_metric. Any part of the Topology Graph which is not connected to a local network address X is not used. Only one selection X SHOULD be made from each I_local_iface_addr_list, and only one selection R SHOULD be made from any L_neighbor_iface_addr_list. All edges have a hop count of 1, except edges W -> T that have a hop count of the corresponding value of AN_dist. 19.2. Populating the Routing Set The Routing Set MUST contain the shortest paths for all destinations from all local OLSRv2 interfaces using the Network Topology Graph. This calculation MAY use any algorithm, including any means of choosing between paths of equal total metric. (In the case of two paths of equal total metric but differing hop counts, the path with the lower hop count SHOULD be used.) Using the notation of Section 19.1, initially "backbone" paths using only edges X -> Y and W -> U need be constructed (using a minimum distance algorithm). Then paths using only a final edge of the other types may be added. These MUST NOT replace backbone paths with the same destination (and paths terminating in an edge Y -> Z SHOULD NOT replace paths with any other form of terminating edge). Each path will correspond to a Routing Tuple. These will be of two types. The first type will represent single edge paths, of type X -> S or X -> Y, by: o R_local_iface_addr := X; o R_next_iface_addr := R; o R_dest_addr := S or Y; o R_dist := 1; o R_metric := edge metric. where R is as defined in Section 19.1 for these types of edges. The second type will represent a multiple edge path, which will always have first edge of type X -> Y, and will have final edge of type W -> U, W -> V, W -> T or Y -> Z. The Routing Tuple will be: o R_local_iface_addr := X; Clausen, et al. Expires April 16, 2012 [Page 76] Internet-Draft OLSRv2 October 2011 o R_next_iface_addr := Y; o R_dest_addr := U, V, T or Z; o R_dist := the total hop count of all edges in the path; o R_metric := the total metric of all edges in the path. Finally, Routing Tuples of the second type whose R_dest_addr is not routable MAY be discarded. An example algorithm for calculating the Routing Set of a router is given in Appendix B. 20. Proposed Values for Parameters This protocol uses all parameters defined in [RFC6130] and additional parameters and defined in this specification. All but one (RX_HOLD_TIME) of these additional parameters are router parameters as defined in [RFC6130]. The proposed values of the additional parameters defined in the following sections are appropriate to the case where all parameters (including those defined in [RFC6130]) have a single value. Proposed values for parameters defined in [RFC6130] are given in that specification. 20.1. Local History Time Parameters o O_HOLD_TIME := 30 seconds 20.2. Message Interval Parameters o TC_INTERVAL := 5 seconds o TC_MIN_INTERVAL := TC_INTERVAL/4 20.3. Advertised Information Validity Time Parameters o T_HOLD_TIME := 3 x TC_INTERVAL o A_HOLD_TIME := T_HOLD_TIME 20.4. Received Message Validity Time Parameters o RX_HOLD_TIME := 30 seconds o P_HOLD_TIME := 30 seconds Clausen, et al. Expires April 16, 2012 [Page 77] Internet-Draft OLSRv2 October 2011 o F_HOLD_TIME := 30 seconds 20.5. Jitter Time Parameters o TP_MAXJITTER := HP_MAXJITTER o TT_MAXJITTER := HT_MAXJITTER o F_MAXJITTER := TT_MAXJITTER 20.6. Hop Limit Parameter o TC_HOP_LIMIT := 255 20.7. Willingness Parameter o WILLINGNESS := WILL_DEFAULT 21. Sequence Numbers Sequence numbers are used in this specification for the purpose of discarding "old" information, i.e., messages received out of order. However with a limited number of bits for representing sequence numbers, wrap-around (that the sequence number is incremented from the maximum possible value to zero) will occur. To prevent this from interfering with the operation of this protocol, the following MUST be observed when determining the ordering of sequence numbers. The term MAXVALUE designates in the following one more than the largest possible value for a sequence number. For a 16 bit sequence number (as are those defined in this specification) MAXVALUE is 65536. The sequence number S1 is said to be "greater than" the sequence number S2 if: o S1 > S2 AND S1 - S2 < MAXVALUE/2 OR o S2 > S1 AND S2 - S1 > MAXVALUE/2 When sequence numbers S1 and S2 differ by MAXVALUE/2 their ordering cannot be determined. In this case, which should not occur, either ordering may be assumed. Thus when comparing two messages, it is possible - even in the presence of wrap-around - to determine which message contains the most recent information. Clausen, et al. Expires April 16, 2012 [Page 78] Internet-Draft OLSRv2 October 2011 22. Extensions An extension to this protocol will need to interact with this specification, and possibly also with [RFC6130]. This protocol is designed to permit such interactions, in particular: o Through accessing, and possibly extending, the information in the Information Bases. All updates to the elements specified in this specification are subject to the constraints specified in [RFC6130] and Appendix D. o Through accessing an outgoing message prior to it being transmitted over any OLSRv2 interface, and to add information to it as specified in [RFC5444]. This MAY include Message TLVs and/or network addresses with associated Address Block TLVs. (Network addresses without new associated TLVs SHOULD NOT be added to messages.) This may, for example, be to allow a security protocol, as suggested in Section 23, to add a TLV containing a cryptographic signature to the message. o Through accessing an incoming message, and potentially discarding it prior to processing by this protocol. This may, for example, allow a security protocol as suggested in Section 23 to perform verification of message signatures and prevent processing and/or forwarding of unverifiable messages by this protocol. o Through accessing an incoming message after it has been completely processed by this protocol. This may, in particular, allow a protocol which has added information, by way of inclusion of appropriate TLVs, or of network addresses associated with new TLVs, access to such information after appropriate updates have been recorded in the Information Bases in this protocol. o Through requesting that a message be generated at a specific time. In that case, message generation MUST still respect the constraints in [RFC6130] and Section 5.4.3. 23. Security Considerations Currently, this protocol does not specify any special security measures. As a proactive routing protocol, this protocol is a potential target for various attacks. Various possible vulnerabilities are discussed in this section. 23.1. Confidentiality This protocol periodically MPR floods topological information to all routers in the network. Hence, if used in an unprotected wireless Clausen, et al. Expires April 16, 2012 [Page 79] Internet-Draft OLSRv2 October 2011 network, the network topology is revealed to anyone who listens to the control messages. In situations where the confidentiality of the network topology is of importance, regular cryptographic techniques, such as exchange of OLSRv2 control traffic messages encrypted by PGP [RFC4880] or encrypted by some shared secret key, can be applied to ensure that control traffic can be read and interpreted by only those authorized to do so. 23.2. Integrity Each router is injecting topological information into the network through transmitting HELLO messages and, for some routers, TC messages. If some routers for some reason, malicious or malfunction, inject invalid control traffic, network integrity may be compromised. Therefore, message authentication is recommended. Different such situations may occur, for instance: 1. a router generates TC messages, advertising links to non-neighbor routers; 2. a router generates TC messages, pretending to be another router; 3. a router generates HELLO messages, advertising non-neighbor routers; 4. a router generates HELLO messages, pretending to be another router; 5. a router forwards altered control messages; 6. a router does not forward control messages; 7. a router does not select multipoint relays correctly; 8. a router forwards broadcast control messages unaltered, but does not forward unicast data traffic; 9. a router "replays" previously recorded control traffic from another router. Authentication of the originator router for control messages (for situations 2, 4 and 5) and on the individual links announced in the control messages (for situations 1 and 3) may be used as a countermeasure. However to prevent routers from repeating old (and correctly authenticated) information (situation 9) temporal Clausen, et al. Expires April 16, 2012 [Page 80] Internet-Draft OLSRv2 October 2011 information is required, allowing a router to positively identify such delayed messages. In general, digital signatures and other required security information may be transmitted as a separate Message Type, or signatures and security information may be transmitted within the HELLO and TC messages, using the TLV mechanism. Either option permits that "secured" and "unsecured" routers can coexist in the same network, if desired, Specifically, the authenticity of entire control packets can be established through employing IPsec authentication headers, whereas authenticity of individual links (situations 1 and 3) require additional security information to be distributed. An important consideration is that all control messages are transmitted either to all routers in the neighborhood (HELLO messages) or broadcast to all routers in the network (TC messages). For example, a control message in this protocol is always a point-to- multipoint transmission. It is therefore important that the authentication mechanism employed permits that any receiving router can validate the authenticity of a message. As an analogy, given a block of text, signed by a PGP private key, then anyone with the corresponding public key can verify the authenticity of the text. 23.3. Interaction with External Routing Domains This protocol does, through the use of TC messages, provide a basic mechanism for injecting external routing information to this protocol's domain. Routing information can be extracted from the protocol's Information Bases, in particular the Routing Set, of this protocol and, potentially, injected into an external domain, if the routing protocol governing that domain permits this. When operating routers connecting a MANET using this protocol to an external routing domain, care MUST be taken not to allow potentially insecure and untrustworthy information to be injected from this domain to external routing domains. Care MUST also be taken to validate the correctness of information prior to it being injected as to avoid polluting routing tables with invalid information. A recommended way of extending connectivity from an existing routing domain to a MANET routed using this protocol is to assign an IP prefix (under the authority of the routers/gateways connecting the MANET with the exiting routing domain) exclusively to that MANET area, and to statically configure the gateways to advertise routes for that IP sequence to routers in the existing routing domain. Clausen, et al. Expires April 16, 2012 [Page 81] Internet-Draft OLSRv2 October 2011 24. IANA Considerations This specification defines one Message Type, which must be allocated from the "Message Types" repository of [RFC5444], two Message TLV Types, which must be allocated from the "Message TLV Types" repository of [RFC5444], and four Address Block TLV Types, which must be allocated from the "Address Block TLV Types" repository of [RFC5444]. 24.1. Expert Review: Evaluation Guidelines For the registries where an Expert Review is required, the designated expert SHOULD take the same general recommendations into consideration as are specified by [RFC5444]. 24.2. Message Types This specification defines one Message Type, to be allocated from the 0-223 range of the "Message Types" namespace defined in [RFC5444], as specified in Table 8. +------+----------------------------------------------+ | Type | Description | +------+----------------------------------------------+ | TBD1 | TC : Topology Control (MANET-wide signaling) | +------+----------------------------------------------+ Table 8: Message Type assignment 24.3. Message-Type-Specific TLV Type Registries IANA is requested to create a registry for Message-Type-specific Message TLVs for TC messages, in accordance with Section 6.2.1 of [RFC5444], and with initial assignments and allocation policies as specified in Table 9. +---------+-------------+-------------------+ | Type | Description | Allocation Policy | +---------+-------------+-------------------+ | 128-223 | Unassigned | Expert Review | +---------+-------------+-------------------+ Table 9: TC Message-Type-specific Message TLV Types IANA is requested to create a registry for Message-Type-specific Address Block TLVs for TC messages, in accordance with Section 6.2.1 of [RFC5444], and with initial assignments and allocation policies as specified in Table 10. Clausen, et al. Expires April 16, 2012 [Page 82] Internet-Draft OLSRv2 October 2011 +---------+-------------+-------------------+ | Type | Description | Allocation Policy | +---------+-------------+-------------------+ | 128-223 | Unassigned | Expert Review | +---------+-------------+-------------------+ Table 10: TC Message-Type-specific Address Block TLV Types 24.4. Message TLV Types This specification defines two Message TLV Types, which must be allocated from the "Message TLV Types" namespace defined in [RFC5444]. IANA is requested to make allocations in the 0-127 range for these types. This will create two new Type Extension registries with assignments as specified in Table 11 and Table 12. Specifications of these TLVs are in Section 13.3.1. Each of these TLVs MUST NOT be included more than once in a Message TLV Block. +-------------+------+-----------+---------------------+------------+ | Name | Type | Type | Description | Allocation | | | | Extension | | Policy | +-------------+------+-----------+---------------------+------------+ | MPR_WILLING | TBD2 | 0 | Bits 0-3 specify | | | | | | the originating | | | | | | router's | | | | | | willingness to act | | | | | | as a flooding MPR; | | | | | | bits 4-7 specify | | | | | | the originating | | | | | | router's | | | | | | willingness to act | | | | | | as a routing MPR | | | MPR_WILLING | TBD2 | 1-255 | Unassigned | Expert | | | | | | Review | +-------------+------+-----------+---------------------+------------+ Table 11: Message TLV Type assignment: MPR_WILLING Clausen, et al. Expires April 16, 2012 [Page 83] Internet-Draft OLSRv2 October 2011 +--------------+------+-----------+--------------------+------------+ | Name | Type | Type | Description | Allocation | | | | Extension | | Policy | +--------------+------+-----------+--------------------+------------+ | CONT_SEQ_NUM | TBD3 | 0 | COMPLETE : | | | | | | Specifies a | | | | | | content sequence | | | | | | number for this | | | | | | complete message | | | CONT_SEQ_NUM | TBD3 | 1 | INCOMPLETE : | | | | | | Specifies a | | | | | | content sequence | | | | | | number for this | | | | | | incomplete message | | | CONT_SEQ_NUM | TBD3 | 2-255 | Unassigned | Expert | | | | | | Review | +--------------+------+-----------+--------------------+------------+ Table 12: Message TLV Type assignment: CONT_SEQ_NUM Type extensions indicated as Expert Review SHOULD be allocated as described in [RFC5444], based on Expert Review as defined in [RFC5226]. 24.5. Address Block TLV Types This specification defines four Address Block TLV Types, which must be allocated from the "Address Block TLV Types" namespace defined in [RFC5444]. IANA are requested to make allocations in the 8-127 range for these types. This will create four new Type Extension registries with assignments as specified in Table 13, Table 14, Table 15 and Table 16. Specifications of these TLVs are in Section 13.3.2. +-------------+------+-----------+-------------------+--------------+ | Name | Type | Type | Description | Allocation | | | | Extension | | Policy | +-------------+------+-----------+-------------------+--------------+ | LINK_METRIC | TBD4 | 0 | Link metric | | | | | | meaning assigned | | | | | | by administrative | | | | | | action | | | LINK_METRIC | TBD4 | 1-223 | Unassigned | Expert | | | | | | Review | | LINK_METRIC | TBD4 | 224-255 | Unassigned | Experimental | | | | | | Use | +-------------+------+-----------+-------------------+--------------+ Table 13: Address Block TLV Type assignment: LINK_METRIC Clausen, et al. Expires April 16, 2012 [Page 84] Internet-Draft OLSRv2 October 2011 All LINK_METRIC TLVs, whatever their type extension, MUST use their value field to encode the kind and value (in the interval MINIMUM_METRIC, to MAXIMUM_METRIC, inclusive) of a link metric as specified in Section 6 and Section 13.3.2. An assignment of a LINK_METRIC TLV type extension MUST specify the physical meaning, and mapping of that physical meaning to the representable values in the indicated interval, of the link metric. +------+------+-----------+----------------------------+------------+ | Name | Type | Type | Description | Allocation | | | | Extension | | Policy | +------+------+-----------+----------------------------+------------+ | MPR | TBD5 | 0 | Specifies that a given | | | | | | network address is of a | | | | | | router selected as a | | | | | | flooding MPR (FLOODING = | | | | | | 1), that a given network | | | | | | address is of a router | | | | | | selected as a routing MPR | | | | | | (ROUTING = 2), or both | | | | | | (FLOOD_ROUTE = 3) | | | MPR | TBD5 | 1-255 | Unassigned | Expert | | | | | | Review | +------+------+-----------+----------------------------+------------+ Table 14: Address Block TLV Type assignment: MPR Clausen, et al. Expires April 16, 2012 [Page 85] Internet-Draft OLSRv2 October 2011 +---------------+------+-----------+-------------------+------------+ | Name | Type | Type | Description | Allocation | | | | Extension | | Policy | +---------------+------+-----------+-------------------+------------+ | NBR_ADDR_TYPE | TBD6 | 0 | Specifies that a | | | | | | given network | | | | | | address is of a | | | | | | neighbor reached | | | | | | via the | | | | | | originating | | | | | | router, if it is | | | | | | an originator | | | | | | address | | | | | | (ORIGINATOR = 1), | | | | | | is a routable | | | | | | address (ROUTABLE | | | | | | = 2), or if it is | | | | | | both | | | | | | (ROUTABLE_ORIG = | | | | | | 3) | | | NBR_ADDR_TYPE | TBD6 | 1-255 | Unassigned | Expert | | | | | | Review | +---------------+------+-----------+-------------------+------------+ Table 15: Address Block TLV Type assignment: NBR_ADDR_TYPE +---------+------+-----------+-------------------------+------------+ | Name | Type | Type | Description | Allocation | | | | extension | | Policy | +---------+------+-----------+-------------------------+------------+ | GATEWAY | TBD7 | 0 | Specifies that a given | | | | | | network address is | | | | | | reached via a gateway | | | | | | on the originating | | | | | | router, with value | | | | | | equal to the number of | | | | | | hops | | | GATEWAY | TBD7 | 1-255 | | Expert | | | | | | Review | +---------+------+-----------+-------------------------+------------+ Table 16: Address Block TLV Type assignment: GATEWAY Type extensions indicated as Expert Review SHOULD be allocated as described in [RFC5444], based on Expert Review as defined in [RFC5226]. Clausen, et al. Expires April 16, 2012 [Page 86] Internet-Draft OLSRv2 October 2011 24.6. NBR_ADDR_TYPE and MPR Values Note: This section does not require any IANA action, as the required information is included in the descriptions of the MPR and NBR_ADDR_TYPE Address Block TLVs allocated in Section 24.5. This information is recorded here for clarity, and for use elsewhere in this specification. The Values which the MPR Address Block TLV can use are the following: o FLOODING := 1; o ROUTING := 2; o FLOOD_ROUTE := 3. The Values which the NBR_ADDR_TYPE Address Block TLV can use are the following: o ORIGINATOR := 1; o ROUTABLE := 2; o ROUTABLE_ORIG := 3. 25. Contributors This specification is the result of the joint efforts of the following contributors -- listed alphabetically. o Cedric Adjih, INRIA, France, o Emmanuel Baccelli, INRIA , France, o Thomas Heide Clausen, LIX, France, o Justin Dean, NRL, USA, o Christopher Dearlove, BAE Systems, UK, o Satoh Hiroki, Hitachi SDL, Japan, o Philippe Jacquet, INRIA, France, o Monden Kazuya, Hitachi SDL, Japan, Clausen, et al. Expires April 16, 2012 [Page 87] Internet-Draft OLSRv2 October 2011 o Kenichi Mase, Niigata University, Japan, o Ryuji Wakikawa, Toyota, Japan, 26. Acknowledgments The authors would like to acknowledge the team behind OLSRv1, specified in RFC3626, including Anis Laouiti (INT, Paris), Pascale Minet (INRIA, France), Laurent Viennot (INRIA, France), and Amir Qayyum (M.A. Jinnah University, Islamabad) for their contributions. The authors would like to gratefully acknowledge the following people for intense technical discussions, early reviews and comments on the specification and its components (listed alphabetically): Khaldoun Al Agha (LRI), Teco Boot (Infinity Networks), Song-Yean Cho (LIX), Alan Cullen (BAE Systems), Ulrich Herberg (Fujitsu), Louise Lamont (CRC), Li Li (CRC), Joe Macker (NRL), Richard Ogier (SRI), Charles E. Perkins (WiChorus), Henning Rogge (FGAN), and the entire IETF MANET working group. 27. References 27.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, BCP 14, March 1997. [RFC5148] Clausen, T., Dearlove, C., and B. Adamson, "Jitter Considerations in Mobile Ad Hoc Networks (MANETs)", RFC 5148, February 2008. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", RFC 5226, BCP 26, May 2008. [RFC5444] Clausen, T., Dean, J., Dearlove, C., and C. Adjih, "Generalized Mobile Ad Hoc Network (MANET) Packet/ Message Format", RFC 5444, February 2009. [RFC5497] Clausen, T. and C. Dearlove, "Representing Multi-Value Time in Mobile Ad Hoc Networks (MANETs)", RFC 5497, March 2009. [RFC5498] Chakeres, I., "IANA Allocations for Mobile Ad Hoc Network (MANET) Protocols", RFC 5498, March 2009. [RFC6130] Clausen, T., Dean, J., and C. Dearlove, "Mobile Ad Hoc Network (MANET) Neighborhood Discovery Protocol (NHDP)", Clausen, et al. Expires April 16, 2012 [Page 88] Internet-Draft OLSRv2 October 2011 RFC 6130, April 2011. 27.2. Informative References [RFC2501] Macker, J. and S. Corson, "Mobile Ad hoc Networking (MANET): Routing Protocol Performance Issues and Evaluation Considerations", RFC 2501, January 1999. [RFC3626] Clausen, T. and P. Jacquet, "The Optimized Link State Routing Protocol", RFC 3626, October 2003. [RFC4880] Callas, J., Donnerhacke, L., Finney, H., and R. Thayer, "OpenPGP message format", RFC 4880, November 2007. [HIPERLAN] ETSI, "ETSI STC-RES10 Committee. Radio equipment and systems: HIPERLAN type 1, functional specifications ETS 300-652", June 1996. [HIPERLAN2] Jacquet, P., Minet, P., Muhlethaler, P., and N. Rivierre, "Increasing reliability in cable free radio LANs: Low level forwarding in HIPERLAN.", 1996. [MPR] Qayyum, A., Viennot, L., and A. Laouiti, "Multipoint relaying: An efficient technique for flooding in mobile wireless networks.", 2001. [FSR] Pei, G., Gerla, M., and T. Chen, "Fisheye state routing in mobile ad hoc networks", 2000. [FSLS] Santivanez, C., Ramanathan, R., and I. Stavrakakis, "Making link-state routing scale for ad hoc networks", 2000. Appendix A. Example Algorithm for Calculating MPRs The following specifies an algorithm which MAY be used to select an MPR Set given a Neighbor Graph, as defined in Section 18.2 and Section 18.3. This algorithm selects an MPR Set M that is a subset of the set N1 that is part of the Neighbor Graph. This algorithm assumes that a subset I of N1 is pre-selected as MPRs, i.e., that M will contain I. A.1. Additional Notation The following additional notation, in addition to that in Section 18.2 will be used by this algorithm: Clausen, et al. Expires April 16, 2012 [Page 89] Internet-Draft OLSRv2 October 2011 N: A subset of N2, consisting of those elements y in N2 such that either d1(y) is not defined, or there is at least one x in N1 such that d(x,y) is defined and d(x,y) < d1(y). D(x): For an element x in N1, the number of elements y in N for which d(x,y) is defined and has minimal value among the d(z,y) for all z in N1. R(x,M): For an element x in N1, the number of elements y in N for which d(x,y) is defined, has minimal value among the d(z,y) for all z in N1, and no such minimal values have z in M. (Note that, denoting the empty set by 0, D(x) = R(x,0).) A.2. MPR Selection Algorithm To create the MPR Set M, starting with M := I: 1. Add all elements x in N1 that have W(x) = WILL_ALWAYS. 2. For each element y in N for which there is only one element x in N1 such that d2(x,y) is defined, add that element x to M. 3. While there exists any element x in N1 with R(x,M) > 0: 1. Select an element x in N1 with R(x,M) > 0 in the following order of priority: + greatest W(x), THEN; + greatest R(x,M), THEN; + greatest D(x), THEN; + any choice, which MAY be based on other criteria (for example a router MAY choose to prefer a neighbor as an MPR if that neighbor has already selected the router as an MPR of the same type, MAY prefer a neighbor based on information freshness, or MAY prefer a neighbor based on length of time previously selected as an MPR) or MAY be random. 4. OPTIONALLY, consider each element x in M, but not in I, in turn and if x can be removed from M while still leaving it satisfying the definition of an MPR Set, then remove that element x from M. Elements MAY be considered in any order, e.g. in order of Clausen, et al. Expires April 16, 2012 [Page 90] Internet-Draft OLSRv2 October 2011 increasing W(x). Appendix B. Example Algorithm for Calculating the Routing Set The following procedure is given as an example for calculating the Routing Set using a variation of Dijkstra's algorithm. First all Routing Tuples are removed, and then, using the selections and definitions in Appendix B.1, the procedures in the following sections (each considered a "stage" of the processing) are applied in turn. B.1. Local Interfaces and Neighbors The following selections and definitions are made: 1. For each Local Interface Tuple, select a network address from its I_local_iface_addr_list, this is defined as the selected address for this Local Interface Tuple. 2. For each Link Tuple, the selected address of its corresponding Local Interface Tuple is defined as the selected local address for this Local Interface Tuple. 3. For each Neighbor Tuple with N_symmetric = true, select a Link Tuple with L_status = SYMMETRIC for which this is the corresponding Neighbor Tuple and has L_out_metric = N_out_metric. This is defined as the selected Link Tuple for this Neighbor Tuple. 4. For each network address (N_orig_addr or in N_neighbor_addr_list, the "neighbor address") from a Neighbor Tuple with N_symmetric = true, select a Link Tuple (the "selected Link Tuple") from those for which this is the corresponding Neighbor Tuple, have L_status = SYMMETRIC, and have L_out_metric = N_out_metric, by: 1. If there is such a Link Tuple whose L_neighbor_iface_addr_list contains the neighbor address, select that Link Tuple. 2. Otherwise select the selected Link Tuple for this Neighbor Tuple. Then for this neighbor address: 3. The selected local address is defined as the selected local address for the selected Link Tuple. 4. The selected link address is defined as an address from the L_neighbor_iface_addr_list of the selected Link Tuple, if Clausen, et al. Expires April 16, 2012 [Page 91] Internet-Draft OLSRv2 October 2011 possible equal to this neighbor address. 5. Routing Tuple preference is decided by preference for minimum R_dist, then for minimum R_dist, and then for preference for corresponding Neighbor Tuples in this order: * For greater N_will_routing. * For N_mpr_selector = true over N_mpr_selector = false. Note that preferred Routing Tuples SHOULD be used. Routing Tuples with minimum R_metric MUST be used, this is specified outside the definition of preference. An implementation MAY modify this definition of preference (including for minimum R_dist) without otherwise affecting this algorithm. B.2. Add Neighbor Routers The following procedure is executed once. 1. For each Neighbor Tuple with N_symmetric = true, add a Routing Tuple with: * R_dest_addr := N_orig_addr; * R_next_iface_addr := selected link address for N_orig_addr; * R_local_iface_addr := selected local address for N_orig_addr; * R_metric := N_out_metric; * R_dist := 1. B.3. Add Remote Routers The following procedure is executed once. 1. Add a label that may be "used" or "unused" to each Routing Tuple, with all initial values equal to unused. (Note that this label is only required during this algorithm.) 2. If there are no unused Routing Tuples then this stage is complete, otherwise repeat the following until that is the case. 1. Find the unused Routing Tuple with minimum R_metric (if more than one, pick any) and denote it the "current Routing Tuple". Clausen, et al. Expires April 16, 2012 [Page 92] Internet-Draft OLSRv2 October 2011 2. Mark the current Routing Tuple as used. 3. For each Router Topology Tuple, with: + TR_from_orig_addr = R_dest_addr of the current Routing Tuple. 2. Define: - new_metric := R_metric of the current Routing Tuple + TR_metric; - new_dist := R_dist of the current Routing Tuple + 1. 3. If there is no Routing Tuple with R_dest_addr = TR_to_orig_addr, then create an unused Routing Tuple with: - R_dest_addr := TR_to_orig_addr; - R_next_iface_addr := R_next_iface_addr of the current Routing Tuple; - R_local_iface_addr := R_local_iface_addr of the current Routing Tuple; - R_metric := new_metric; - R_dist := new_dist. 4. Otherwise, if there is an unused Routing Tuple with R_dest_addr = TR_to_orig_addr, and either new_metric < R_metric or (new_metric = R_metric and the updated Routing Tuple would be preferred) then update this Routing Tuple to have: - R_next_iface_addr := R_next_iface_addr of the current Routing Tuple; - R_local_iface_addr := R_local_iface_addr of the current Routing Tuple; - R_metric := new_metric; - R_dist := new_dist. Clausen, et al. Expires April 16, 2012 [Page 93] Internet-Draft OLSRv2 October 2011 B.4. Add Neighbor Addresses The following procedure is executed once. 1. For each Neighbor Tuple with N_symmetric = true: 1. For each network address (the "neighbor address") in N_neighbor_addr_list, if the neighbor address is not equal to the R_dest_addr of any Routing Tuple, then add a new Routing Tuple, with: + R_dest_addr := neighbor address; + R_next_iface_addr := selected link address for the neighbor address; + R_local_iface_addr := selected local address for the neighbor address; + R_metric := N_out_metric; + R_dist := 1. B.5. Add Remote Routable Addresses The following procedure is executed once. 1. For each Routable Address Topology Tuple, if: * TA_dest_addr is not equal to the R_dest_addr of any Routing Tuple added in an earlier stage, AND; * TA_from_orig_addr is equal to the R_dest_addr of a Routing Tuple (the "previous Routing Tuple"), then add a new Routing Tuple, with: * R_dest_addr := TA_dest_addr; * R_next_iface_addr := R_next_iface_addr of the previous Routing Tuple; * R_local_iface_addr := R_local_iface_addr of the previous Routing Tuple; * R_metric := R_metric of the previous Routing Tuple + TA_metric. Clausen, et al. Expires April 16, 2012 [Page 94] Internet-Draft OLSRv2 October 2011 * R_dist := R_dist of the previous Routing Tuple + 1. There may be more than one Routing Tuple that may be added for an R_dest_addr in this stage. If so, then, for each such R_dest_addr, a Routing Tuple with minimum R_metric MUST be selected, otherwise a Routing Tuple which is preferred SHOULD be added. B.6. Add Attached Networks The following procedure is executed once. 1. For each Attached Network Tuple, if: * AN_net_addr is not equal to the R_dest_addr of any Routing Tuple added in an earlier stage, AND; * AN_orig_addr is equal to the R_dest_addr of a Routing Tuple (the "previous Routing Tuple), then add a new Routing Tuple, with: * R_dest_addr := AN_net_addr; * R_next_iface_addr := R_next_iface_addr of the previous Routing Tuple; * R_local_iface_addr := R_local_iface_addr of the previous Routing Tuple; * R_metric := R_metric of the previous Routing Tuple + AN_metric; * R_dist := R_dist of the previous Routing Tuple + AN_dist. There may be more than one Routing Tuple that may be added for an R_dest_addr in this stage. If so, then, for each such R_dest_addr, a Routing Tuple with minimum R_metric MUST be selected, otherwise a Routing Tuple which is preferred SHOULD be added. B.7. Add 2-Hop Neighbors The following procedure is executed once. 1. For each 2-Hop Tuple, if: Clausen, et al. Expires April 16, 2012 [Page 95] Internet-Draft OLSRv2 October 2011 * N2_2hop_addr is a routable address, AND; * N2_2hop_addr is not equal to the R_dest_addr of any Routing Tuple added in an earlier stage, AND; * the Routing Tuple with R_dest_addr = N_orig_addr of the corresponding Neighbor Tuple (the "previous Routing Tuple") has R_dist = 1, then add a new Routing Tuple, with: * R_dest_addr := N2_2hop_addr; * R_next_iface_addr := R_next_iface_addr of the previous Routing Tuple; * R_local_iface_addr := R_local_iface_addr of the previous Routing Tuple; * R_metric := R_metric of the previous Routing Tuple + N_out_metric of the corresponding Neighbor Tuple; * R_dist := 2. There may be more than one Routing Tuple that may be added for an R_dest_addr in this stage. If so, then, for each such R_dest_addr, a Routing Tuple with minimum R_metric MUST be selected, otherwise a Routing Tuple which is preferred SHOULD be added. Appendix C. TC Message Example TC messages are instances of [RFC5444] messages. This specification requires that TC messages contains and fields. It supports TC messages with any combination of remaining message header options and address encodings, enabled by [RFC5444] that convey the required information. As a consequence, there is no single way to represent how all TC messages look. This appendix illustrates a TC message, the exact values and content included are explained in the following text. The TC message's four bit Message Flags (MF) field has value 15 indicating that the message header contains originator address, hop limit, hop count, and message sequence number fields. Its four bit Message Address Length (MAL) field has value 3, indicating addresses in the message have a length of four octets, here being IPv4 addresses. The overall message length is 71 octets. Clausen, et al. Expires April 16, 2012 [Page 96] Internet-Draft OLSRv2 October 2011 The message has a Message TLV Block with content length 13 octets containing three TLVs. The first two TLVs are validity and interval times for the message. The third TLV is the content sequence number TLV used to carry the 2 octet ANSN, and (with default type extension zero, i.e., COMPLETE) indicating that the TC message is complete. Each TLV uses a TLV with Flags octet (MTLVF) value 16, indicating that it has a Value, but no type extension or start and stop indexes. The first two TLVs have a Value Length of 1 octet, the last has a Value Length of 2 octets. The message has two Address Blocks. (This is not necessary, the information could be conveyed using a single Address Block, the use of two Address Blocks, which is also allowed, is illustrative only.) The first Address Block contains 3 addresses, with Flags octet (ATLVF) value 128, hence with a Head section (with length 2 octets), but no Tail section, and hence with Mid sections with length two octets. The following TLV Block (content length 13 octets) contains two TLVs. The first TLV is a NBR_ADDR_TYPE TLV with Flags octet (ATLVF) value 16, indicating a single Value but no indexes. Thus all three addresses are associated with the Value (with Value Length 1 octet) ROUTABLE_ORIG, i.e., they are originator addresses of advertised neighbors that are also routable addresses. The second TLV is a LINK_STATUS TLV with Flags octet (ATLVF) value 20, indicating a Value for each address, i.e. as the total Value Length is 6 octets, each address is associated with a Value with length two octets. These Value fields are each shown as having four bits indicating that they are outgoing neighbor metric values, and as having twelve bits that represent the metric value (the first four bits being the exponent, the remaining twelve bits the mantissa). The second Address Block contains 1 address, with Flags octet (ATLVF) 176, indicating that there is a Head section (with length 2 octets), that the Tail section (with length 2 octets) consists of zero valued octets (not included), and that there is a single prefix length, which is 16. The network address is thus Head.0.0/16. The following TLV Block (content length 8 octets) includes two TLVs. The first has a Flags octet (ATLVF) of 16, again indicating that no indexes are needed, but that a Value (with Value Length 1 octet) is present, indicating the address distance as a number of hops. The second TLV is another LINK_METRIC TLV, as in the first Address TLV Block except with a Flags octet (ATLVF) value 16, indicating that a single Value is present. Clausen, et al. Expires April 16, 2012 [Page 97] Internet-Draft OLSRv2 October 2011 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TC | MF=15 | MAL=3 | Message Length = 71 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Originator Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Hop Limit | Hop Count | Message Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message TLV Block Length = 13 | VALIDITY_TIME | MTLVF = 16 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Value Len = 1 | Value (Time) | INTERVAL_TIME | MTLVF = 16 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Value Len = 1 | Value (Time) | CONT_SEQ_NUM | MTLVF = 16 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Value Len = 2 | Value (ANSN) | Num Addrs = 3 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ABF = 128 | Head Len = 2 | Head | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Mid | Mid | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Mid | Address TLV Block Length = 13 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | NBR_ADDR_TYPE | ATLVF = 16 | Value Len = 1 | ROUTABLE_ORIG | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LINK_METRIC | ATLVF = 20 | Value Len = 6 |0|0|0|1|Metric | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Metric (cont) |0|0|0|1| Metric |0|0|0|1|Metric | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Metric (cont) | Num Addrs = 1 | ABF = 176 | Head Len = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Head | Tail Len = 2 | Pref Len = 16 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Address TLV Block Length = 9 | GATEWAY | ATLVF = 16 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Value Len = 1 | Value (Hops) | LINK_METRIC | ATLVF = 16 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Value Len = 2 |0|0|0|1| Metric | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Appendix D. Constraints Any process which updates the Local Information Base, the Neighborhood Information Base or the Topology Information Base MUST ensure that all constraints specified in this appendix are maintained, as well as those specified in [RFC6130]. In each Originator Tuple: Clausen, et al. Expires April 16, 2012 [Page 98] Internet-Draft OLSRv2 October 2011 o O_orig_addr MUST NOT equal any other O_orig_addr. o O_orig_addr MUST NOT equal this router's originator address. In each Local Attached Network Tuple: o AL_net_addr MUST NOT equal any other AL_net_addr. o AL_net_addr MUST NOT equal or be a sub-range of any network address in the I_local_iface_addr_list of any Local Interface Tuple. o AL_net_addr MUST NOT equal this router's originator address, or equal the O_orig_addr in any Originator Tuple. o AL_dist MUST NOT be less than zero. In each Link Tuple: o L_neighbor_iface_addr_list MUST NOT contain any network address that AL_net_addr of any Local Attached Network Tuple equals or is a sub-range of. o If L_status = HEARD or L_status = SYMMETRIC then L_in_metric != UNKNOWN_METRIC. o If L_status = SYMMETRIC then L_in_metric != UNKNOWN_METRIC. o if L_in_metric != UNKNOWN_METRIC then L_in_metric MUST be representable in the defined compressed form. o if L_out_metric != UNKNOWN_METRIC then L_out_metric MUST be representable in the defined compressed form. o If L_mpr_selector = true, then L_status = SYMMETRIC. In each Neighbor Tuple: o N_orig_addr MUST NOT be changed to unknown. o N_orig_addr MUST NOT equal this router's originator address, or equal O_orig_addr in any Originator Tuple. o N_orig_addr MUST NOT equal the AL_net_addr in any Local Attached Network Tuple. o If N_orig_addr != unknown, then N_orig_addr MUST NOT equal the N_orig_addr in any other Neighbor Tuple. Clausen, et al. Expires April 16, 2012 [Page 99] Internet-Draft OLSRv2 October 2011 o N_neighbor_addr_list MUST NOT contain any network address which includes this router's originator address, the O_orig_addr in any Originator Tuple, or equal or have as a sub-range the AL_net_addr in any Local Attached Network Tuple. o If N_orig_addr = unknown, then N_will_flooding = WILL_NEVER, N_will_routing = WILL_NEVER, N_flooding_mpr, N_routing_mpr = false, N_mpr_selector = false, and N_advertised = false. o N_in_metric MUST equal the minimum value of the L_in_metric values of all corresponding Link Tuples, if any, otherwise N_in_metric = UNKNOWN_METRIC. o N_out_metric MUST equal the minimum value of the L_out_metric values of all corresponding Link Tuples, if any, otherwise N_out_metric = UNKNOWN_METRIC. o N_will_flooding and N_will_routing MUST be in the range from WILL_NEVER to WILL_ALWAYS, inclusive. o If N_flooding_mpr = true, then N_symmetric MUST be true and N_will_flooding MUST NOT equal WILL_NEVER. o If N_routing_mpr = true, then N_symmetric MUST be true and N_will_routing MUST NOT equal WILL_NEVER. o If N_symmetric = true and N_flooding_mpr = false, then N_will_flooding MUST NOT equal WILL_ALWAYS. o If N_symmetric = true and N_routing_mpr = false, then N_will_routing MUST NOT equal WILL_ALWAYS. o If N_mpr_selector = true, then N_advertised MUST be true. o If N_advertised = true, then N_symmetric MUST be true. In each Lost Neighbor Tuple: o NL_neighbor_addr MUST NOT include this router's originator address, the O_orig_addr in any Originator Tuple, or equal or have as a sub-range the AL_net_addr in any Local Attached Network Tuple. In each 2-Hop Tuple: o N2_2hop_addr MUST NOT equal this router's originator address, equal the O_orig_addr in any Originator Tuple, or equal or have as a sub-range the AL_net_addr in any Local Attached Network Tuple Clausen, et al. Expires April 16, 2012 [Page 100] Internet-Draft OLSRv2 October 2011 o N2_in_metric and N2_out_metric MUST be representable in the defined compressed form. In each Advertising Remote Router Tuple: o AR_orig_addr MUST NOT be in any network address in the I_local_iface_addr_list in any Local Interface Tuple or be in the IR_local_iface_addr in any Removed Interface Address Tuple. o AR_orig_addr MUST NOT equal this router's originator address or equal the O_orig_addr in any Originator Tuple. o AR_orig_addr MUST NOT be in the AL_net_addr in any Local Attached Network Tuple. o AR_orig_addr MUST NOT equal the AR_orig_addr in any other Advertising Remote Router Tuple. In each Router Topology Tuple: o There MUST be an Advertising Remote Router Tuple with AR_orig_addr = TR_from_orig_addr. o TR_to_orig_addr MUST NOT be in any network address in the I_local_iface_addr_list in any Local Interface Tuple or be in the IR_local_iface_addr in any Removed Interface Address Tuple. o TR_to_orig_addr MUST NOT equal this router's originator address or equal the O_orig_addr in any Originator Tuple. o TR_to_orig_addr MUST NOT be in the AL_net_addr in any Local Attached Network Tuple. o The ordered pair (TR_from_orig_addr, TR_to_orig_addr) MUST NOT equal the corresponding pair for any other Router Topology Tuple. o TR_seq_number MUST NOT be greater than AR_seq_number in the Advertising Remote Router Tuple with AR_orig_addr = TR_from_orig_addr. o TR_metric MUST be representable in the defined compressed form. In each Routable Address Topology Tuple: o There MUST be an Advertising Remote Router Tuple with AR_orig_addr = TA_from_orig_addr. Clausen, et al. Expires April 16, 2012 [Page 101] Internet-Draft OLSRv2 October 2011 o TA_dest_addr MUST be routable. o TA_dest_addr MUST NOT overlap any network address in the I_local_iface_addr_list in any Local Interface Tuple or overlap the IR_local_iface_addr in any Removed Interface Address Tuple. o TA_dest_addr MUST NOT include this router's originator address or include the O_orig_addr in any Originator Tuple. o TA_dest_addr MUST NOT equal or have as a sub-range the AL_net_addr in any Local Attached Network Tuple. o The ordered pair (TA_from_orig_addr, TA_dest_addr) MUST NOT equal the corresponding pair for any other Attached Network Tuple. o TA_seq_number MUST NOT be greater than AR_seq_number in the Advertising Remote Router Tuple with AR_orig_addr = TA_from_orig_addr. o TA_metric MUST be representable in the defined compressed form. In each Attached Network Tuple: o There MUST be an Advertising Remote Router Tuple with AR_orig_addr = AN_orig_addr. o AN_net_addr MUST NOT equal or be a sub-range of any network address in the I_local_iface_addr_list in any Local Interface Tuple or be a sub-range of the IR_local_iface_addr in any Removed Interface Address Tuple. o AN_net_addr MUST NOT equal this router's originator address or equal the O_orig_addr in any Originator Tuple. o AN_net_addr MUST NOT equal the AL_net_addr in any Local Attached Network Tuple. o The ordered pair (AN_orig_addr, AN_net_addr) MUST NOT equal the corresponding pair for any other Attached Network Tuple. o AN_seq_number MUST NOT be greater than AR_seq_number in the Advertising Remote Router Tuple with AR_orig_addr = AN_orig_addr. o AN_dist MUST NOT be less than zero. o AN_metric MUST be representable in the defined compressed form. Clausen, et al. Expires April 16, 2012 [Page 102] Internet-Draft OLSRv2 October 2011 Appendix E. Flow and Congestion Control Due to its proactive nature, this protocol has a natural control over the flow of its control traffic. Routers transmit control messages at predetermined rates specified and bounded by message intervals. This protocol employs [RFC6130] for local signaling, embedding MPR selection advertisement through a simple Address Block TLV, and router willingness advertisement (if any) as a single Message TLV. Local signaling, therefore, shares the characteristics and constraints of [RFC6130]. Furthermore, the use of MPRs can greatly reduce the signaling overhead from link state information dissemination in two ways, attaining both flooding reduction and topology reduction. First, using MPR flooding, the cost of distributing link state information throughout the network is reduced, as compared to when using classic flooding, since only MPRs need to forward link state declaration messages. Second, the amount of link state information for a router to declare is reduced to need only contain that router's MPR selectors. This reduces the size of a link state declaration as compared to declaring full link state information. In particular some routers may not need to declare any such information. In dense networks, the reduction of control traffic can be of several orders of magnitude compared to routing protocols using classical flooding [MPR]. This feature naturally provides more bandwidth for useful data traffic and pushes further the frontier of congestion. Since the control traffic is continuous and periodic, it keeps the quality of the links used in routing more stable. However, using some options, some control messages (HELLO messages or TC messages) may be intentionally sent in advance of their deadline in order to increase the responsiveness of the protocol to topology changes. This may cause a small, temporary, and local increase of control traffic, however this is at all times bounded by the use of minimum message intervals. Authors' Addresses Thomas Heide Clausen LIX, Ecole Polytechnique Phone: +33 6 6058 9349 EMail: T.Clausen@computer.org URI: http://www.ThomasClausen.org/ Clausen, et al. Expires April 16, 2012 [Page 103] Internet-Draft OLSRv2 October 2011 Christopher Dearlove BAE Systems ATC Phone: +44 1245 242194 EMail: chris.dearlove@baesystems.com URI: http://www.baesystems.com/ Philippe Jacquet Project Hipercom, INRIA Phone: +33 1 3963 5263 EMail: philippe.jacquet@inria.fr Clausen, et al. Expires April 16, 2012 [Page 104]