Mobile Ad hoc Networks Working S. Ratliff Group B. Berry Internet-Draft G. Harrison Intended status: Standards Track D. Satterwhite Expires: March 3, 2013 Cisco Systems S. Jury NetApp August 30, 2012 Dynamic Link Exchange Protocol (DLEP) draft-ietf-manet-dlep-03 Abstract When routing devices rely on modems to effect communications over wireless links, they need timely and accurate knowledge of the characteristics of the link (speed, state, etc.) in order to make forwarding decisions. In mobile or other environments where these characteristics change frequently, manual configurations or the inference of state through routing or transport protocols does not allow the router to make the best decisions. A bidirectional, event- driven communication channel between the router and the modem is necessary. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on February 21, 2013. Ratliff et al. Expires March 3, 2013 [Page 1] Internet-Draft DLEP August 2012 Copyright Notice Copyright (c) 2012 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Requirements . . . . . . . . . . . . . . . . . . . . . . . 7 2. Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3. Credits . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4. Metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 5. Extensions to DLEP . . . . . . . . . . . . . . . . . . . . . . 10 6. Normal Session Flow . . . . . . . . . . . . . . . . . . . . . . 10 7. Mandatory Signals and Data Items . . . . . . . . . . . . . . . 12 8. Generic DLEP Packet Definition . . . . . . . . . . . . . . . . 13 9. DLEP Data Items . . . . . . . . . . . . . . . . . . . . . . . . 13 9.1 Identification . . . . . . . . . . . . . . . . . . . . . . 14 9.2 DLEP Version . . . . . . . . . . . . . . . . . . . . . . . 15 9.3 Peer Type . . . . . . . . . . . . . . . . . . . . . . . . . 16 9.4 MAC Address . . . . . . . . . . . . . . . . . . . . . . . . 16 9.5 IPv4 Address . . . . . . . . . . . . . . . . . . . . . . . 17 9.6 IPv6 Address . . . . . . . . . . . . . . . . . . . . . . . 18 9.7 Maximum Data Rate . . . . . . . . . . . . . . . . . . . . . 18 9.8 Current Data Rate . . . . . . . . . . . . . . . . . . . . . 19 9.9 Expected Forwarding Time . . . . . . . . . . . . . . . . . 20 9.10 Latency . . . . . . . . . . . . . . . . . . . . . . . . . 20 9.11 Resources . . . . . . . . . . . . . . . . . . . . . . . . 21 9.12 Relative Link Quality . . . . . . . . . . . . . . . . . . 22 9.13 Status . . . . . . . . . . . . . . . . . . . . . . . . . . 22 9.14 Heartbeat Interval/Threshold . . . . . . . . . . . . . . . 23 9.15 Link Characteristics ACK Timer . . . . . . . . . . . . . . 24 9.16 Credit Window Status . . . . . . . . . . . . . . . . . . . 24 9.17 Credit Grant Request . . . . . . . . . . . . . . . . . . . 25 9.18 Credit Request . . . . . . . . . . . . . . . . . . . . . . 26 10. DLEP Protocol Messages . . . . . . . . . . . . . . . . . . . . 27 10.1 Signal TLV Values . . . . . . . . . . . . . . . . . . . . 27 11. Peer Discovery Message . . . . . . . . . . . . . . . . . . . . 28 Ratliff et al. Expires March 3, 2013 [Page 2] Internet-Draft DLEP August 2012 12. Peer Offer Message . . . . . . . . . . . . . . . . . . . . . . 28 13. Peer Offer ACK Message . . . . . . . . . . . . . . . . . . . . 29 14. Peer Update Message . . . . . . . . . . . . . . . . . . . . . 30 15. Peer Update ACK Message . . . . . . . . . . . . . . . . . . . 31 16. Peer Termination Message . . . . . . . . . . . . . . . . . . . 31 17. Peer Termination ACK Message . . . . . . . . . . . . . . . . . 31 18. Neighbor Up Message . . . . . . . . . . . . . . . . . . . . . 32 19. Neighbor Up ACK Message . . . . . . . . . . . . . . . . . . . 32 20. Neighbor Down Message . . . . . . . . . . . . . . . . . . . . 33 21. Neighbor Down ACK Message . . . . . . . . . . . . . . . . . . 33 22. Neighbor Update Message . . . . . . . . . . . . . . . . . . . 34 23. Heartbeat Message . . . . . . . . . . . . . . . . . . . . . . 34 24. Link Characteristics Request Message . . . . . . . . . . . . . 35 25. Link Characteristics ACK Message . . . . . . . . . . . . . . . 36 26. Security Considerations . . . . . . . . . . . . . . . . . . . 36 27. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 36 27.1 Registrations . . . . . . . . . . . . . . . . . . . . . . 36 27.2 Expert Review: Evaluation Guidelines . . . . . . . . . . . 37 27.3 Signal (Message) TLV Type Registration . . . . . . . . . . 37 27.4 DLEP Data Item Registrations . . . . . . . . . . . . . . . 38 27.5 DLEP Well-known Port . . . . . . . . . . . . . . . . . . . 38 27.6 DLEP Multicast Address . . . . . . . . . . . . . . . . . . 38 30. Appendix A. . . . . . . . . . . . . . . . . . . . . . . . . . 38 30.1 Peer Level Message Flows . . . . . . . . . . . . . . . . . 38 30.1.1 Modem Device Restarts Discovery . . . . . . . . . . . 38 30.1.2 Modem Device Detects Peer Offer Timeout . . . . . . . 39 30.1.3 Router Peer Offer Lost . . . . . . . . . . . . . . . . 40 30.1.4 Discovery Success . . . . . . . . . . . . . . . . . . 40 30.1.5 Router Detects a Heartbeat timeout . . . . . . . . . . 41 30.1.6 Modem Detects a Heartbeat timeout . . . . . . . . . . 41 30.1.7 Peer Terminate (from Modem) Lost . . . . . . . . . . . 42 30.1.8 Peer Terminate (from Router) Lost . . . . . . . . . . 42 30.2 Neighbor Specific Message Flows . . . . . . . . . . . . . 42 30.2.1 Modem Neighbor Up Lost . . . . . . . . . . . . . . . . 43 30.2.2 Router Detects Duplicate Neighbor Ups . . . . . . . . 43 30.2.3 Neighbor Up, No Layer 3 Addresses . . . . . . . . . . 44 30.2.4 Neighbor Up with IPv4, No IPv6 . . . . . . . . . . . . 44 30.2.5 Neighbor Up with IPv4 and IPv6 . . . . . . . . . . . . 44 30.2.6 Neighbor Session Success . . . . . . . . . . . . . . . 45 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . 45 Normative References . . . . . . . . . . . . . . . . . . . . . . . 45 Informative References . . . . . . . . . . . . . . . . . . . . . . 46 Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . . 46 1. Introduction There exist today a collection of modem devices that control links of variable bandwidth and quality. Examples of these types of links Ratliff et al. Expires March 3, 2013 [Page 3] Internet-Draft DLEP August 2012 include line-of-sight (LOS) radios, satellite terminals, and cable/DSL modems. Fluctuations in speed and quality of these links can occur due to configuration (in the case of cable/DSL modems), or on a moment-to-moment basis, due to physical phenomena like multipath interference, obstructions, rain fade, etc. It is also quite possible that link quality and bandwidth varies with respect to individual neighbors on a link, and with the type of traffic being sent. As an example, consider the case of an 802.11g access point, serving 2 associated laptop computers. In this environment, the answer to the question "What is the bandwidth on the 802.11g link?" is "It depends on which associated laptop we're talking about, and on what kind of traffic is being sent." While the first laptop, being physically close to the access point, may have a bandwidth of 54Mbps for unicast traffic, the other laptop, being relatively far away, or obstructed by some object, can simultaneously have a bandwidth of only 32Mbps for unicast. However, for multicast traffic sent from the access point, all traffic is sent at the base transmission rate (which is configurable, but depending on the model of the access point, is usually 24Mbps or less). In addition to utilizing variable bandwidth links, mobile networks are challenged by the notion that link connectivity will come and go over time. Effectively utilizing a relatively short-lived connection is problematic in IP routed networks, as routing protocols tend to rely on independent timers at OSI Layer 3 to maintain network convergence (e.g. HELLO messages and/or recognition of DEAD routing adjacencies). These short-lived connections can be better utilized with an event-driven paradigm, where acquisition of a new neighbor (or loss of an existing one) is signaled, as opposed to a timer- driven paradigm. Another complicating factor for mobile networks are the different methods of physically connecting the modem devices to the router. Modems can be deployed as an interface card in a router's chassis, or as a standalone device connected to the router via Ethernet, USB, or even a serial link. In the case of Ethernet or serial attachment, with existing protocols and techniques, routing software cannot be aware of convergence events occurring on the radio link (e.g. acquisition or loss of a potential routing neighbor), nor can the router be aware of the actual capacity of the link. This lack of awareness, along with the variability in bandwidth, leads to a situation where quality of service (QoS) profiles are extremely difficult to establish and properly maintain. This is especially true of demand-based access schemes such as Demand Assigned Multiple Access (DAMA) implementations used on some satellite systems. With a DAMA-based system, additional bandwidth may be available, but will not be used unless the network devices emit traffic at rate higher than the currently established rate. Increasing the traffic rate does Ratliff et al. Expires March 3, 2013 [Page 4] Internet-Draft DLEP August 2012 not guarantee additional bandwidth will be allocated; rather, it may result in data loss and additional retransmissions on the link. Addressing the challenges listed above, the authors have developed the Data Link Exchange Protocol, or DLEP. The DLEP protocol runs between a router and its attached modem devices, allowing the modem to communicate link characteristics as they change, and convergence events (acquisition and loss of potential routing neighbors). The following diagrams are used to illustrate the scope of DLEP packets. |-------Local Node-------| |-------Remote Node------| | | | | +--------+ +-------+ +-------+ +--------+ | Router |=======| Modem |{~~~~~~~~}| Modem |=======| Router | | | | Device| | Device| | | +--------+ +-------+ +-------+ +--------+ | | | Link | | | |-DLEP--| | Protocol | |-DLEP--| | | | (e.g. | | | | | | 802.11) | | | Figure 1: DLEP Network In Figure 1, when the local modem detects the presence of a remote node, it (the local modem) sends a signal to its router via the DLEP protocol. Upon receipt of the signal, the local router may take whatever action it deems appropriate, such as initiating discovery protocols, and/or issuing HELLO messages to converge the network. On a continuing, as-needed basis, the modem devices utilize DLEP to report any characteristics of the link (bandwidth, latency, etc) that have changed. DLEP is independent of the link type and topology supported by the modem. Figure 2 shows how DLEP can support a configuration where routers are connected with different link types. In this example, Modem A implements a point-to-point link, and Modem B is connected via a shared medium. In both cases, the DLEP protocol is used to report the characteristics of the link (bandwidth, latency, etc.) to routers. The modem is also able to use the DLEP session to notify the router when the remote node is lost, shortening the time required to re- converge the network. +--------+ +--------+ +----+ Modem A| | Modem A+---+ | | Device | <===== // ======> | Device | | | +--------+ P-2-P Link +--------+ | +---+----+ +---+----+ | Router | | Router | Ratliff et al. Expires March 3, 2013 [Page 5] Internet-Draft DLEP August 2012 | | | | +---+----+ +---+----+ | +--------+ +--------+ | +-----+ Modem B| | Modem B| | | Device | o o o o o o o o | Device +--+ +--------+ o Shared o +--------+ o Medium o o o o o o o o +--------+ | Modem B| | Device | +---+----+ | | +---+----+ | Router | | | +--------+ Figure 2: DLEP Network with Multiple Modem Devices DLEP defines a set of logical signals used by modems and their attached routers. The signals are used to communicate events that occur on the physical link(s) managed by the modem: for example, a remote node entering or leaving the network, or that the link has changed. Associated with these signals are a set of data items - information that describes the remote node (e.g., address information), and/or the characteristics of the link to the remote node. The protocol is defined as a collection of type-length-value (TLV) based messages, specifying the signals that are exchanged between a router and a modem, and the data items associated with the signal. This document specifies transport of DLEP signals and data items via the UDP transport. Other transports for the protocol are possible, but are outside the scope of this document. DLEP signals are further defined as mandatory or optional. Signals will additionally have mandatory and optional data items. Implementations MUST support all mandatory signals and their mandatory data items to be considered compliant. Implementations MAY also support some, or all, of the optional signals and data items. DLEP uses a session-oriented paradigm between the modem device and its associated router. If multiple modem devices are attached to a Ratliff et al. Expires March 3, 2013 [Page 6] Internet-Draft DLEP August 2012 router (as in Figure 2), a separate DLEP session MUST exist for each modem. If a modem device supports multiple connections to a router (via multiple logical or physical interfaces), or supports connections to multiple routers, a separate DLEP session MUST exist for each connection. This router/modem session provides a carrier for information exchange concerning neighbors (remote nodes) that are accessible via the modem device. As such, all of the neighbor-level exchanges in DLEP can be envisioned as building an information base concerning the remote nodes, and the link characteristics to those nodes. Multicast traffic is handled in IP networks by deriving a Layer 2 MAC address based on the Layer 3 address. Leveraging on this scheme, Multicast traffic is supported in DLEP simply by treating the derived MAC address as any other destination in the network. To support these logical destinations, one of the DLEP participants (typically, the router) informs the other as to the existence of the logical neighbor. The modem, once it is aware of the existence of this logical neighbor, reports link characteristics just as it would for any other destination in the network. The specific algorithms a modem would use to report metrics on multicast (or logical) destinations is outside the scope of this specification, and is left to specific implementations to decide. 1.1 Requirements The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14, RFC 2119 [RFC2119]. 2. Assumptions Routers and modems that exist as part of the same node (e.g., that are locally connected) can utilize a discovery technique to locate each other, thus avoiding a-priori configuration. Either entity (the router or the modem) can initiate the discovery process. In cases where both entities initiate discovery, a race condition can occur. When this race condition occurs, the router MUST cease its active discovery, and respond to the modem's request. DLEP utilizes a session-oriented paradigm. A router and modem form a session by completing the discovery process. This router-modem session persists unless or until it either (1) times out, based on the timeout values supplied, or (2) is explicitly torn down by one of the participants. Note that use of timers in DLEP is OPTIONAL; that is, implementations can choose to run with no timers (or effectively, timers set to an infinite value). Ratliff et al. Expires March 3, 2013 [Page 7] Internet-Draft DLEP August 2012 DLEP assumes that participating modems, and their physical links, act as a transparent bridge. Specifically, the assumption is that the destination MAC address for data traffic in any frame emitted by the router should be the MAC address of a device in the remote node. DLEP also assumes that MAC addresses are unique within the context of the router-modem session. This document refers to a remote node as a "Neighbor". Neighbors can be identified by either the router or the modem, and represent a specific destination (e.g., an address) that exists on the link(s) managed by the modem. Examples of a destination include a MAC address, a unicast Layer 3 address, or a multicast Layer 3 address. As "neighbors" are discovered, DLEP routers and modems build an information base on destinations accessible via the modem. Changes in link characteristics MAY then be reported as being "modem-wide" (effecting ALL neighbors accessed via the modem) or MAY be neighbor (destination) specific. The DLEP signals concerning neighbors thus become the way for routers and modems to maintain, and notify each other about, an information base representing the physical and logical (e.g., multicast) destinations accessible via the modem device. The information base would contain addressing information (e.g., MAC address, and OPTIONALLY, Layer 3 addresses), link characteristics (metrics), and OPTIONALLY, flow control information (credits). DLEP assumes that security on the session (e.g. authentication of session partners, encryption of traffic, or both) is dealt with by the underlying transport mechanism (e.g., by using a transport such as DTLS [DTLS]). Sequence Numbers for DLEP messages start at 0 and are incremented by one for each original and retransmitted message. The unsigned 16-bit Sequence Number rolls over at 65535 to 0. Sequence Numbers are unique within the context of a DLEP session. Sequence numbers are used in DLEP to correlate a response to a request. This document specifies an implementation of the DLEP signals and data items running over the UDP transport, utilizing a well-known UDP Port number. It is assumed that DLEP running over other transport mechanisms would be documented separately. 3. Credits DLEP includes an OPTIONAL credit-windowing scheme analogous to the one documented in [RFC5578]. In this scheme, traffic between the router and modem is treated as two unidirectional windows. This Ratliff et al. Expires March 3, 2013 [Page 8] Internet-Draft DLEP August 2012 document identifies these windows as the "Modem Receive Window", or MRW, and the "Router Receive Window", or RRW. If credits are used, they MUST be granted by the receiver on a given window - that is, on the "Modem Receive Window" (MRW), the modem is responsible for granting credits to the router, allowing it (the router) to send data to the modem. Likewise, the router is responsible for granting credits on the RRW, which allows the modem to send data to the router. DLEP expresses all credit data in number of octets. The total number of credits on a window, and the increment to add to a grant, are always expressed as a 64-bit unsigned quantity. If used, credits are managed on a neighbor-specific basis; that is, separate credit counts are maintained for each neighbor requiring the service. Credits do not apply to the DLEP session that exists between routers and modems. 4. Metrics DLEP includes the ability for the router and modem to communicate metrics that reflect the characteristics (e.g. bandwidth, latency) of the variable-quality link in use. As mentioned in the introduction section of this document, metrics have to be used within a context - for example, metrics to a unicast address in the network. DLEP allows for metrics to be sent within two contexts - metrics for a specific neighbor (those for a given destination within the network), and "modem-wide" (those that apply to all destinations accessed via the modem). Metrics supplied on DLEP Peer signals are, by definition, modem-wide; metrics supplied on Neighbor signals are, by definition, used for the specific neighbor only. It is left to implementations to choose sensible default values based on their specific characteristics. Additionally, this mechanism (either at a modem-wide or specific neighbor context) MAY be used to report non-changing, or static, metrics. Modems having static link metric characteristics MAY report metrics only once for a given neighbor (or once on a modem-wide basis, if all connections via the modem are of this static nature). The approach of allowing for different contexts for metric data increases both the flexibility and the complexity of using metric data. This document details the mechanism whereby the data is transmitted, however, the specific algorithms (precedence, etc) for utilizing the dual-context metrics is out of scope and not addressed by this document. Ratliff et al. Expires March 3, 2013 [Page 9] Internet-Draft DLEP August 2012 5. Extensions to DLEP While this draft represents the best efforts of the co-authors, and the working group, to be functionally complete, it is recognized that extensions to DLEP will in all likelihood be necessary as more link types are utilized. To allow for future innovation, the draft allocates numbering space for experimental implementations of both signals and data items. DLEP implementations MUST be capable of parsing and acting on the mandatory signals and data items as documented in this specification. DLEP signals/data items that are optional, or are in the experimental numbering range SHOULD be silently dropped by an implementation if they are not understood. The intent of the optional signals and data items, as well as the experimental numbering space, is to allow for further development of DLEP protocol features and function. Having experimental space reserved for both signals and data items gives maximum flexibility for extending the protocol as conditions warrant. For example, experimental data items could be used by implementations to send additional metrics. A combination of experimental signals, and associated data items, could be used to implement new flow control schemes. If subsequent research and development define new features and function, then it should be standardized either as an update to this document, or as an additional stand-alone specification. 6. Normal Session Flow At the start of a run, DLEP implementations (both router and modem) initialize the communications path. In a UDP implementation, this includes opening a socket and binding to the well-known port address (TBD). Once the communications path is established, an implementation would either, depending on configuration, proceed to periodically issue a "Peer Discovery" message. The Peer Discovery MAY be sent either via the multicast address allocated for DLEP (TBD), or via a unicast address, or drop into a "passive receive" mode, waiting on receipt of a Peer Discovery. Both modem and router initialize in a "discovery" state. Either the modem, the router, or both, will then issue a "Peer Discovery" signal. The Peer Discovery signal MAY be issued to a unicast address (if a-priori knowledge of the address exists), or to the multicast address TBD. The receiver of a Peer Discovery message responds with a "Peer Offer" signal to indicate readiness to participate in the DLEP session. The Ratliff et al. Expires March 3, 2013 [Page 10] Internet-Draft DLEP August 2012 receiver of a Peer Offer message responds with a "Peer Offer ACK" message, completing discovery. While the Peer Discovery message MAY be sent to the DLEP multicast address (TBD), the Peer Offer, and all subsequent traffic, is sent to the unicast address that originated the Peer Discovery. Once the Peer Offer signal is acknowledged, both participants (router and modem) transition to the "in session" state, creating a logical, stateful session between the modem and the router. Subsequent DLEP signals are then processed within the context of this router/modem session. DLEP partners use these signals to build their respective information bases regarding destinations that are accessible via the modem, and link characteristics associated with those destinations. The "in session" state created by the discovery signals is maintained until one of the following conditions occur: o The session is explicitly terminated (using Peer Termination), or o The session times out, based on supplied timeout values. In order to maintain the session between router and modem, OPTIONAL periodic "Heartbeat" messages MAY be exchanged. These messages are intended to keep the session alive, and to verify bidirectional connectivity between the two participants. DLEP also provides for an OPTIONAL Peer Update message, intended to communicate some change in status (e.g., a change of layer 3 address parameters, or a modem-wide link change). In addition to the messages above, the participants will transmit DLEP messages concerning destinations in the network. These messages trigger creation/maintenance/deletion of "neighbors" in the information base of the recipient. For example, a modem will inform its attached router of the presence of a new destination via the "Neighbor Up" signal. Receipt of a Neighbor Up causes the router to allocate the necessary resources, creating an entry in the information base with the specifics (e.g., MAC Address, Latency, Data Rate, etc) of the neighbor. The loss of a destination is communicated via the "Neighbor Down" signal, and changes in status to the destination (e.g. varying link quality, or addressing changes) are communicated via the "Neighbor Update" signal. The information on a given neighbor will persist in the router's information base until (1) a "Neighbor Down" is received, indicating that the modem has lost contact with the remote node, or (2) the router/modem session terminates, indicating that the router has lost contact with its own local modem. Again, metrics can be expressed within the context of a specific neighbor via the Neighbor Update message, or on a modem-wide basis via the Peer Update message. In cases where metrics are provided on Ratliff et al. Expires March 3, 2013 [Page 11] Internet-Draft DLEP August 2012 the router/modem session, the receiver MUST propagate the metrics to all neighbors in its information base that are accessed via the originator. A DLEP participant MAY send metrics both in a router/modem session context (via the Peer Update message) and a specific neighbor context (via Neighbor Update) at any time. The heuristics for applying received metrics is left to implementations. In addition to receiving metrics about the link, DLEP provides an OPTIONAL signal allowing a router to request a different amount of bandwidth, or latency, from the modem. This signal is referred to as the Link Characteristics Message, and gives the router the ability to deal with requisite increases (or decreases) of allocated bandwidth/latency in demand-based schemes in a more deterministic manner. 7. Mandatory Signals and Data Items The following DLEP signals are considered core to the specification; implementations MUST support these signals, and the associated data items, in order to be considered compliant: Signal Data Items ====== ========== Attached Peer Discovery Identification Peer Offer Identification Peer Offer ACK Status Peer Termination Identification Peer Termination ACK Status Neighbor Up Identification MAC Address Maximum Data Rate Current Data Rate Latency Resources Relative Link Quality Neighbor Update Identification MAC Address Maximum Data Rate Current Data Rate Latency Resources Relative Link Quality Ratliff et al. Expires March 3, 2013 [Page 12] Internet-Draft DLEP August 2012 Neighbor Down Identification MAC Address All other DLEP signals and data items are OPTIONAL. Implementations MAY choose to provide them. Implementations that do not support optional signals and data items SHOULD parse, and silently drop, all unsupported signals and/or data items. 8. Generic DLEP Packet Definition The Generic DLEP Packet consists of a sequence of TLVs. The first TLV represents the signal being communicated (e.g., a "Neighbor Up", or a "Peer Offer"). Subsequent TLVs contain the data items pertinent to the signal (e.g., Maximum Data Rate, or Latency, etc). The Generic DLEP Packet Definition contains the following fields: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Signal TLV Type | Length | DLEP data items... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Signal - One of the DLEP Signal TLV type values defined in this document. Length - The length of all of the DLEP data items associated with this signal. DLEP data items - One or more data items, encoded in TLVs, as defined in this document. 9. DLEP Data Items As mentioned earlier, DLEP protocol messages are transported as a collection of TLVs. The first TLV present in a DLEP message MUST be one of the Signal TLVs, documented in section [INSERT REFERENCE HERE]. The signals are followed by one or more data items, indicating the specific changes that need to be instantiated in the receiver's information base. Valid DLEP Data Items are: TLV TLV Value Description ========================================= Ratliff et al. Expires March 3, 2013 [Page 13] Internet-Draft DLEP August 2012 TBD Identification TBD DLEP Version TBD Peer Type TBD IPv4 Address TBD IPv6 Address TBD Maximum Data Rate (MDR) TBD Current Data Rate (CDR) TBD Latency TBD Resources TBD Expected Forwarding Time (EFT) TBD Relative Link Quality (RLQ) TBD Status TBD Heartbeat Interval/Threshold TBD Neighbor down ACK timer TBD Link Characteristics ACK timer TBD Credit Window Status TBD Credit Grant TBD Credit Request DLEP data item TLVs contain the following fields: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TLV Type | Length | Value... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - An 8-bit unsigned integer field specifying the data item being sent. Length - An 8-bit length of the value field of the data item Value - A field of length which contains data specific to a particular data item. 9.1 Identification This data item MUST exist in all DLEP messages, and MUST be the first data item of the message (e.g., it MUST immediately follow the signal TLV). Further, there MUST be ONLY one Identification data item in a DLEP message. The data item contains identification information used to establish the proper context (e.g., the router/modem session) for processing DLEP protocol messages. The format of the Identification Data Item is: 0 1 2 3 Ratliff et al. Expires March 3, 2013 [Page 14] Internet-Draft DLEP August 2012 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type = TBD | Length = 8 | Router ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Router ID | Modem ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Modem ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - Value TBD Length - 8 Router ID - Indicates the Router ID of the DLEP session. Modem ID - indicates the Modem ID of the DLEP session. During transmission of a DLEP Peer Discovery signal, the transmitter MUST set its ID to a 32-bit quantity that will be used to uniquely identify this session from the transmitter's perspective. The other ID value MUST be set the to '0'. When responding to the Peer Discovery signal (via the Peer Offer signal), the transmitter MUST echo any received ID value, and MUST supply its own unique 32-bit quantity to identify the session from its perspective. After the Peer Discovery/Peer Offer exchange, subsequent signals on this DLEP session MUST contain the ID values obtained from the Peer Discovery/Peer Offer sequence. 9.2 DLEP Version The DLEP Version TLV is an OPTIONAL TLV in both the Peer Discovery and Peer Offer messages. The Version TLV is used to indicate the version of the protocol running in the originator. A participant MAY use this information to decide if the potential session partner is running at a supported level. The DLEP Version TLV contains the following fields: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length=4 | Major Version | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Minor Version | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Ratliff et al. Expires March 3, 2013 [Page 15] Internet-Draft DLEP August 2012 Length - Length is 4 Major Version - Major version of the modem or router protocol. Minor Version - Minor version of the modem or router protocol. Support of this draft is indicated by setting the Major Version to '1', and the Minor Version to '3' (e.g. Version 1.3). 9.3 Peer Type The Peer Type TLV is an OPTIONAL TLV in both the Peer Discovery and Peer Offer messages. The Peer Type TLV is used by the router and modem to give additional information as to its type. The peer type is a string and is envisioned to be used for informational purposes (e.g. as output in a display command). The Peer Type TLV contains the following fields: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length= peer |Peer Type String | | |type string len|Max Len = 80 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - Length of peer type string (80 octets maximum). Peer Type String - Non-Null terminated string, maximum length of 80 octets. For example, a satellite modem might set this variable to 'Satellite terminal'. 9.4 MAC Address The MAC address TLV MUST appear in all neighbor-oriented signals (e.g. Neighbor Up, Neighbor Up ACK, Neighbor Down, Neighbor Down ACK, Neighbor Update, Link Characteristics Request, and Link Characteristics ACK). The MAC Address TLV contains the address of the destination on the remote node. The MAC address MAY be either a physical or a virtual destination. Examples of a virtual destination would be a multicast MAC address, or the broadcast MAC (0xFFFFFFFFFFFF). 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 Ratliff et al. Expires March 3, 2013 [Page 16] Internet-Draft DLEP August 2012 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 6 | MAC Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MAC Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 6 MAC Address - MAC Address of the destination (either physical or virtual). 9.5 IPv4 Address The IPv4 Address TLV is an OPTIONAL TLV. If supported, it MAY appear in Neighbor Up, Neighbor Update, and Peer Update messages. When included in Neighbor messages, the IPv4 Address TLV contains the IPv4 address of the neighbor, as well as a subnet mask value. In the Peer Update message, it contains the IPv4 address of the originator of the message. In either case, the TLV also contains an indication of whether this is a new or existing address, or is a deletion of a previously known address. The IPv4 Address TLV contains the following fields: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 6 | Add/Drop | IPv4 Address | | | | Indicator | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv4 Address | Subnet Mask | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 6 Add/Drop - Value indicating whether this is a new or existing IPv4 address IPv4 Address - The IPv4 address of the neighbor or peer. Subnet Mask - A subnet mask (0-32) to be applied to the IPv4 address. Ratliff et al. Expires March 3, 2013 [Page 17] Internet-Draft DLEP August 2012 9.6 IPv6 Address The IPv6 Address TLV is an OPTIONAL TLV. If supported, it MAY be used in the Neighbor Up, Neighbor Update, Peer Discovery, and Peer Update Messages. When included in Neighbor messages, this data item contains the IPv6 address of the neighbor. In the Peer Discovery and Peer Update, it contains the IPv6 address of the originating peer. In either case, the data item also contains an indication of whether this is a new or existing address, or is a deletion of a previously known address, as well as a subnet mask. The IPv6 Address TLV contains the following fields: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 18 | Add/Drop | IPv6 Address | | | | Indicator | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | IPv6 Address | Subnet Mask | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 18 Add/Drop - Value indicating whether this is a new or existing address (0x01), or a withdrawal of an address (0x02). IPv6 Address - IPv6 Address of the neighbor or peer. Subnet Mask - A subnet mask value (0-128) to be applied to the Ipv6 address. 9.7 Maximum Data Rate The Maximum Data Rate (MDR) TLV is used in Neighbor Up, Neighbor Update, Peer Discovery, Peer Update, and Link Characteristics ACK Messages to indicate the maximum theoretical data rate, in bits per second, that can be achieved on the link. When metrics are reported via the messages listed above, the maximum data rate MUST be Ratliff et al. Expires March 3, 2013 [Page 18] Internet-Draft DLEP August 2012 reported. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 8 | MDR (bps) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MDR (bps) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MDR (bps) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 8 Maximum Data Rate - A 64-bit unsigned number, representing the maximum theoretical data rate, in bits per second (bps), that can be achieved on the link. 9.8 Current Data Rate The Current Data Rate (CDR) TLV is used in Neighbor Up, Neighbor Update, Peer Discovery, Peer Update, Link Characteristics Request, and Link Characteristics ACK messages to indicate the rate at which the link is currently operating, or in the case of the Link Characteristics Request, the desired data rate for the link. When metrics are reported via the messages above, the current data rate MUST be reported. The Current Data Rate TLV contains the following fields: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |TLV Flags=0x10 |Length = 8 |CDR (bps) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | CDR (bps) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | CDR (bps) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 8 Current Data Rate - A 64-bit unsigned number, representing the Ratliff et al. Expires March 3, 2013 [Page 19] Internet-Draft DLEP August 2012 current data rate, in bits per second, that is currently be achieved on the link, or the desired data rate in bits per second in the Link Characteristics Request message. If there is no distinction between current and maximum data rates, current data rate MUST be set equal to the maximum data rate. 9.9 Expected Forwarding Time The Expected Forwarding Time (EFT) TLV is is an OPTIONAL data item. If supported, it MAY be used in Neighbor Up, Neighbor Update, Peer Discovery, and Peer Update messages to indicate the typical latency between the arrival of a given packet at the transmitting device and the reception of the packet at the other end of the link. EFT combines transmission time, idle time, waiting time, freezing time, and queuing time to the degree that those values are meaningful to a given transmission medium. The Expected Forwarding Time TLV contains the following fields: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 4 | EFT (ms) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | EFT (ms) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 4 EFT - A 32-bit unsigned number, representing the expected forwarding time, in milliseconds, on the link. 9.10 Latency The Latency TLV is used in Neighbor Up, Neighbor Update, Peer Discovery, Peer Update, Link Characteristics Request, and Link Characteristics ACK messages to indicate the amount of latency on the link, or in the case of the Link Characteristics Request, to indicate the maximum latency required on the link. When metrics are reported via the messages above, Latency MUST be reported. 0 1 2 3 Ratliff et al. Expires March 3, 2013 [Page 20] Internet-Draft DLEP August 2012 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 2 | Latency (ms) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 2 Latency - A 16-bit unsigned value, representing the transmission delay that a packet encounters as it is transmitted over the link. In Neighbor Up, Neighbor Update, and Link Characteristics ACK, this value is reported as delay, in milliseconds. The calculation of latency is implementation dependent. For example, the latency may be a running average calculated from the internal queuing. If a device cannot calculate latency, it MUST be reported as 0. In the Link Characteristics Request Message, this value represents the maximum delay, in milliseconds, expected on the link. 9.11 Resources The Resources TLV is used in Neighbor Up, Neighbor Update, Peer Discovery, Peer Update, and Link Characteristics ACK messages to indicate a percentage (0-100) amount of resources (e.g. battery power) remaining on the originating peer. If metrics are reported, via the above messages, Resources MUST be reported. The Resources TLV contains the following fields: 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 1 | Resources | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 1 Resources - A percentage, 0-100, representing the amount of remaining resources, such as battery power. If resources cannot be calculated, a value of 100 MUST be reported. Ratliff et al. Expires March 3, 2013 [Page 21] Internet-Draft DLEP August 2012 9.12 Relative Link Quality The Relative Link Quality (RLQ) TLV is used in Neighbor Up, Neighbor Update, Peer Discovery, Peer Update, and Link Characteristics ACK messages to indicate the quality of the link as calculated by the originating peer. If metrics are reported via the above messages, RLQ MUST be reported. The Relative Link Quality TLV contains the following fields: 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 1 |Relative Link | | | |Quality (RLQ) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 1 Relative Link Quality - A non-dimensional number, 0-100, representing relative link quality. A value of 100 represents a link of the highest quality. If the RLQ cannot be calculated, a value of 100 MUST be reported. 9.13 Status The Status TLV is an OPTIONAL TLV. It is sent as part of an acknowledgement message, from either the modem or the router, to indicate the success or failure of a given request. The Status TLV contains the following fields: 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 1 | Code | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 1 Termination Code - 0 = Success, Non-zero = Failure. Specific values of a non-zero termination code depend on the Ratliff et al. Expires March 3, 2013 [Page 22] Internet-Draft DLEP August 2012 operation requested (e.g. Neighbor Up, Neighbor Down, etc). 9.14 Heartbeat Interval/Threshold The Heartbeat Interval/Threshold TLV is an OPTIONAL TLV. If supported, it MAY be sent during Peer Discovery to indicate the desired Heartbeat timeout window. If the modem includes the Heartbeat Interval TLV in Peer Discovery, the router MUST either accept the timeout interval supplied by the modem, or reject the Peer Discovery. Peer Discovery messages that do not include the Heartbeat Interval TLV in Peer Discovery indicates a desire to establish the router/modem session without an activity timeout (e.g. an infinite timeout value). If an activity timeout is supported, implementations MAY choose to implement heuristics such that signals sent/received reset the timer window. The Interval is used to specify a period (in seconds) for Heartbeat Messages (See Section 23). The Threshold value is used to indicate the desired number of windows, each of time (Heartbeat Interval) seconds, to wait before either participant declares the router/modem session lost. In this case, the overall amount of time before a router/modem is declared lost is expressed as (Interval * Threshold). Specifying an Interval value of 0 indicates the desire to disable Heartbeat messages entirely (e.g., the Interval is set to an infinite value). Setting the Threshold value to 0 is undefined, and TLVs with a Threshold value of 0 MUST be rejected by the recipient. The Heartbeat Interval/Threshold TLV contains the following fields: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 1 | Interval | Threshold | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 1 Interval - 0 = Do NOT use heartbeats on this peer-to-peer session. Non-zero = Interval, in seconds, for heartbeat messages. Threshold - Number of windows, of Heartbeat Interval seconds, to wait before declaring a peer-to-peer session to be lost. Ratliff et al. Expires March 3, 2013 [Page 23] Internet-Draft DLEP August 2012 9.15 Link Characteristics ACK Timer The Link Characteristics ACK Timer TLV is an OPTIONAL TLV. If supported, it MAY be sent during Peer Discovery to indicate the desired number of seconds to wait for a response to a Link Characteristics Request. If a router receives this TLV from a modem during Peer Discovery, the router MUST either accept the timeout value, or reject the Peer Discovery. If this TLV is omitted, implementations supporting the Link Characteristics Request SHOULD choose a default value. The Link Characteristics ACK Timer TLV contains the following fields: 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 1 | Interval | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 1 Interval - 0 = Do NOT use timeouts for Link Characteristics requests on this router/modem session. Non-zero = Interval, in seconds, to wait before considering a Link Characteristics Request has been lost. 9.16 Credit Window Status The Credit Window Status TLV is an OPTIONAL TLV. If credits are supported by the DLEP participants (both the router and the modem), the Credit Window Status TLV MUST be sent by the participant receiving a Credit Grant Request for a given neighbor. The Credit Window Status TLV contains the following fields: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 16 | Modem Receive Window Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Modem Receive Window Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Modem Receive Window Value | Router Receive Window Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Router Receive Window Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Ratliff et al. Expires March 3, 2013 [Page 24] Internet-Draft DLEP August 2012 | Router Receive Window Value | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 16 Modem Receive Window Value - A 64-bit unsigned number, indicating the current (or initial) number of credits available on the Modem Receive Window. Router Receive Window Value - A 64-bit unsigned number, indicating the current (or initial) number of credits available on the Router Receive Window. 9.17 Credit Grant Request The Credit Grant Request TLV is an OPTIONAL TLV. If credits are supported, the Credit Grant Request TLV is sent from a DLEP participant to grant an increment to credits on a window. The Credit Grant TLV is sent as a data item in either the Neighbor Up or Neighbor Update messages. The value in a Credit Grant TLV represents an increment to be added to any existing credits available on the window. Upon successful receipt and processing of a Credit Grant TLV, the receiver MUST respond with a message containing a Credit Window Status TLV to report the updated aggregate values for synchronization purposes. In the Neighbor Up message, when credits are desired, the originating peer MUST set the initial credit value of the window it controls (e.g. the Modem Receive Window, or Router Receive Window) to an initial, non-zero value. If the receiver of a Neighbor Up message with a Credit Grant Request TLV supports credits, the receiver MUST either reject the use of credits, via a Neighbor Up ACK response with the correct Status TLV, or set the initial value from the data contained in the Credit Window Status TLV. If the initialization completes successfully, the receiver MUST respond to the Neighbor Up message with a Neighbor Up ACK message that contains a Credit Window Status TLV, initializing its receive window. The Credit Grant TLV contains the following fields: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Ratliff et al. Expires March 3, 2013 [Page 25] Internet-Draft DLEP August 2012 |TLV Type =TBD |Length = 8 | Credit Increment | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Credit Increment | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Credit Increment | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 8 Reserved - A 64-bit unsigned number representing the additional credits to be assigned to the credit window. Since credits can only be granted by the receiver on a window, the applicable credit window (either the MRW or the RRW) is derived from the sender of the grant. The Credit Increment MUST NOT cause the window to overflow; if this condition occurs, implementations MUST set the credit window to the maximum value contained in a 64-bit quantity. 9.18 Credit Request The Credit Request TLV is an OPTIONAL TLV. If credits are supported, the Credit Request TLV MAY be sent from either DLEP participant, via a Neighbor Update signal, to indicate the desire for the partner to grant additional credits in order for data transfer to proceed on the session. If the corresponding Neighbor Up message for this session did NOT contain a Credit Window Status TLV, indicating that credits are to be used on the session, then the Credit Request TLV MUST be rejected by the receiver via a Neighbor Update ACK message. The Credit Request TLV contains the following fields: 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |TLV Type =TBD |Length = 0 | Reserved, MUST| | | | be set to 0 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ TLV Type - TBD Length - 0 Reserved - This field is currently unused and MUST be set to 0. Ratliff et al. Expires March 3, 2013 [Page 26] Internet-Draft DLEP August 2012 10. DLEP Protocol Messages DLEP messages are encoded as a string of Type-Length-Value (TLV) constructs. The first TLV in a DLEP message MUST be a valid DLEP signal, as defined in section 11.1 of this document. The second TLV MUST be the Identification data item, defined in section 10.1 Following those two TLVs are 0 or more TLVs, representing the data items that are appropriate for the signal. The layout of a DLEP message is thus: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | DLEP Signal |DLEP Message |Identification |Identification | | Type value |length (9 + |TLV Type |TLV length | | (value TBD) |optional TLVs) |(TBD) |(8) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Router ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Modem ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Start of optional DLEP | | TLVs... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ All DLEP messages (signals) begin with this structure. Therefore, in the following descriptions of specific messages, this header structure is assumed, and will not be replicated. 10.1 Signal TLV Values As mentioned above, all DLEP messages begin with the Type value of the appropriate DLEP signal. Valid DLEP signals are: TLV TLV Value Description ========================================= TBD Peer Discovery TBD Peer Offer TBD Peer Offer ACK TBD Peer Update TBD Peer Update ACK TBD Peer Termination TBD Peer Termination ACK TBD Neighbor Up TBD Neighbor Up ACK TBD Neighbor Down Ratliff et al. Expires March 3, 2013 [Page 27] Internet-Draft DLEP August 2012 TBD Neighbor Down ACK TBD Neighbor Update TBD Heartbeat TBD Link Characteristics Request TBD Link Characteristics ACK 11. Peer Discovery Message The Peer Discovery Message is sent to begin a new DLEP association. The Peer Offer message is required to complete the discovery process. Implementations MAY implement their own retry heuristics in cases where it is determined the Peer Discovery Message has timed out. A Peer Discovery Message received from a participant that is already in session MUST be processed as if a Peer Termination Message had been received. An implementation MAY then process the received Peer Discovery Message. Note that metric data items MAY be supplied with the Peer Discovery, in order to populate default metric values, or to indicate a static, modem-wide environment. If metrics are supplied with the Peer Discovery message, these metrics MUST be used as the initial values for all neighbors established via the modem. Given the packet format described in section 11, the initial TLV Type value is set to DLEP_PEER_DISCOVERY (value TBD). Mandatory TLVs are then placed into the packet: Mandatory Data Item TLVs: - Identification After the Mandatory data item, implementations MAY place any OPTIONAL TLVs they support: Optional Data Item TLVs: - DLEP Version - DLEP Peer Type - Heartbeat Interval - Heartbeat Threshold - Link Characteristics ACK Timer - Maximum Data Rate - Current Data Rate - Latency - Expected Forwarding Time - Resources - Relative Link Quality 12. Peer Offer Message Ratliff et al. Expires March 3, 2013 [Page 28] Internet-Draft DLEP August 2012 The Peer Offer Message is sent by a DLEP participant in response to a Peer Discovery Message. Upon receipt, and successful processing, of a Peer Offer message, the recipient MUST respond with a Peer Offer ACK message, completing the discovery phase of DLEP. Both DLEP participants (router and modem) would then enter an "in session" state. Any subsequent Discovery messages sent or received on this session MUST be considered an error, and the session MUST be terminated as if a Peer Termination Message had been received. The Peer Offer message MUST be sent to the unicast address of the originator of Peer Discovery, regardless of whether the discovery was received on the DLEP multicast address (TBD) or on a unicast address. To construct a Peer Offer message, the initial TLV type value is set to DLEP_PEER_OFFER (value TBD). The Identification data item TLV is placed in the packet next, followed by any OPTIONAL Data Item TLVs the implementation supports: Optional Data Item TLVs: - DLEP Version - Peer Type - IPv4 Address - IPv6 Address - Status - Heartbeat Interval - Heartbeat Threshold - Link Characteristics ACK Timer 13. Peer Offer ACK Message The Peer Offer ACK message acknowledges receipt of a Peer Offer message, and completes the router/modem session establishment for DLEP. The Peer Offer ACK message MUST be sent to unicast address of the originator of a Peer Offer message. The Peer Offer ACK message MAY contain an OPTIONAL Status data item, indicating success or failure of the attempt to establish a router/modem session. For implementations that do NOT support the Status data item (defined in section 10.13 of this document), the Peer Offer ACK message MUST be used ONLY to indicate successful session establishment; Peer Offer messages that are rejected MUST be silently dropped, allowing the Peer Offer to time out. To construct a Peer Offer ACK message, the initial TLV type value is set to DLEP_PEER_OFFER_ACK (value TBD). Mandatory data item TLV's are placed into the packet next: Ratliff et al. Expires March 3, 2013 [Page 29] Internet-Draft DLEP August 2012 Mandatory Data Item TLVs: - Identification - Status Note that there are NO OPTIONAL data item TLVs specifed for this message. 14. Peer Update Message The Peer Update message is an OPTIONAL message, sent by a DLEP peer to indicate local Layer 3 address changes, or for metric changes on a modem-wide basis. For example, addition of an IPv4 address to the router would prompt a Peer Update message to its attached DLEP modems. Also, a modem that changes its Maximum Data Rate for all destinations MAY reflect that change via a Peer Update Message to its attached router(s). Concerning Layer 3 addresses, if the modem is capable of understanding and forwarding this information (via proprietary mechanisms), the address update would prompt any remote DLEP modems (DLEP-enabled modems in a remote node) to issue a "Neighbor Update" message to their local routers with the new (or deleted) addresses. Modems that do not track Layer 3 addresses SHOULD silently parse and ignore the Peer Update Message. Modems that track Layer 3 addresses MUST acknowledge the Peer Update with a Peer Update ACK message. Routers receiving a Peer Update with metric changes MUST apply the new metric to all neighbors (remote nodes) accessible via the modem. Supporting implementations are free to employ heuristics to retransmit Peer Update messages. The sending of Peer Update Messages for Layer 3 address changes SHOULD cease when a either participant (router or modem) determines that the other implementation does NOT support Layer 3 address tracking. If metrics are supplied with the Peer Update message (e.g. Maximum Data Rate), these metrics are considered to be modem-wide, and therefore MUST be applied to all neighbors in the information base associated with the router/modem session. To construct a Peer Update message, the initial TLV type value is set to DLEP_PEER_UPDATE (value TBD). The Identification data item TLV is placed in the packet next, followed by any OPTIONAL Data Item TLVs. Optional Data Item TLVs: - IPv4 Address - IPv6 Address - Maximum Data Rate - Current Data Rate Ratliff et al. Expires March 3, 2013 [Page 30] Internet-Draft DLEP August 2012 - Latency - Expected Forwarding Time - Resources - Relative Link Quality 15. Peer Update ACK Message The Peer Update ACK message is an OPTIONAL message, and is sent by implementations supporting Layer 3 address tracking and/or modem-wide metrics to indicate whether a Peer Update Message was successfully processed. To construct a Peer Update ACK message, the initial TLV type value is set to DLEP_PEER_UPDATE_ACK (value TBD). The Identification data item TLV is placed in the packet next, followed by any OPTIONAL TLVs the implementation supports: Optional Data Item TLVs: - Status 16. Peer Termination Message The Peer Termination Message is sent by a DLEP participant when the router/modem session needs to be terminated. Implementations receiving a Peer Termination message MUST send a Peer Termination ACK message to confirm the termination process. The sender of a Peer Termination message is free to define its heuristics in event of a timeout. The receiver of a Peer Termination Message MUST release all resources allocated for the router/modem session, and MUST eliminate all neighbors in the information base accessible via the router/modem pair represented by the session. Router and modem state machines are returned to the "discovery" state. No Neighbor Down messages are sent. To construct a Peer Termination message, the initial TLV type value is set to DLEP_PEER_TERMINATION (value TBD). The Identification data item TLV is placed in the packet next, followed by any OPTIONAL Data Item TLVs the implementation supports: Optional Data Item TLVs: - Status 17. Peer Termination ACK Message The Peer Termination Message ACK is sent by a DLEP peer in response to a received Peer Termination order. Receipt of a Peer Termination Ratliff et al. Expires March 3, 2013 [Page 31] Internet-Draft DLEP August 2012 ACK message completes the teardown of the router/modem session. To construct a Peer Termination ACK message, the initial TLV type value is set to DLEP_PEER_TERMINATION_ACK (value TBD). The Identification data item TLV is placed in the packet next, followed by any OPTIONAL TLVs the implementation supports: Optional Data Item TLVs: - Status 18. Neighbor Up Message A DLEP participant sends the Neighbor Up message to report that a new destination has been detected. A Neighbor Up ACK Message is required to confirm a received Neighbor Up. A Neighbor Up message can be sent either by the modem, to indicate that a new remote node has been detected, or by the router, to indicate the presence of a new logical destination (e.g., a Multicast group) exists in the network. The sender of the Neighbor Up Message is free to define its retry heuristics in event of a timeout. When a Neighbor Up message is received and successfully parsed, the receiver should add knowledge of the new destination to its information base, indicating that the destination is accessible via the modem/router pair. To construct a Neighbor Up message, the initial TLV type value is set to DLEP_NEIGHBOR_UP (value TBD). The Identification data item TLV is placed in the packet next, followed by the MAC Address TLV, indicating the MAC address of the remote node or Multicast group. The implementation would then place any supported OPTIONAL Data Item TLVs into the packet: Optional Data Item TLVs: - IPv4 Address - IPv6 Address - Maximum Data Rate - Current Data Rate - Latency - Expected Forwarding Time - Resources - Relative Link Factor - Credit Window Status 19. Neighbor Up ACK Message A DLEP participant sends the Neighbor Up ACK Message to indicate Ratliff et al. Expires March 3, 2013 [Page 32] Internet-Draft DLEP August 2012 whether a Neighbor Up Message was successfully processed. To construct a Neighbor Up ACK message, the initial TLV type value is set to DLEP_NEIGHBOR_UP_ACK (value TBD). The Identification data item TLV is placed in the packet next, followed by the MAC Address TLV, containing the MAC address of the DLEP neighbor. The implementation would then place any supported OPTIONAL Data Item TLVs into the packet: Optional Data Item TLVs: - Credit Window Status 20. Neighbor Down Message A DLEP peer sends the Neighbor Down message to report when a destination (a remote node or a multicast group) is no longer reachable. The Neighbor Down message MUST contain both the Identification data item TLV, and a MAC Address data item TLV. Other TLVs as listed are OPTIONAL, and MAY be present if an implementation supports them. A Neighbor Down ACK Message MUST be sent by the recipient of a Neighbor Down message to confirm that the relevant data has been removed from the information base. The sender of the Neighbor Down message is free to define its retry heuristics in event of a timeout. To construct a Neighbor Down message, the initial TLV type value is set to DLEP_NEIGHBOR_DOWN (value TBD). The signal TLV is followed by the mandatory data item TLVs: - Identification - MAC Address Data item - Status data item Note that there are NO OPTIONAL data item TLVs for this message. 21. Neighbor Down ACK Message A DLEP participant sends the Neighbor Down ACK Message to indicate whether a received Neighbor Down Message was successfully processed. If successfully processed, the sender of the ACK MUST have removed all entries in the information base that pertain to the referenced neighbor. As with the Neighbor Down message, there are NO OPTIONAL Data Item TLVs defined for the Neighbor Down ACK message. To construct a Neighbor Down message, the initial TLV type value is set to DLEP_NEIGHBOR_DOWN_ACK (value TBD). The Identification data item TLV is placed in the packet next, followed by: Ratliff et al. Expires March 3, 2013 [Page 33] Internet-Draft DLEP August 2012 - MAC Address Data item - Status data item 22. Neighbor Update Message A DLEP participant sends the Neighbor Update message when it detects some change in the information base for a given neighbor (remote node or multicast group). Some examples of changes that would prompt a Neighbor Update message are: - Change in link metrics (e.g., Data Rates) - Layer 3 addressing change (for implementations that support it) To construct a Neighbor Update message, the initial TLV type value is set to DLEP_NEIGHBOR_UPDATE (value TBD). Following the signal TLV are the mandatory Data Item TLVs: Identification Data Item TLV MAC Address data item TLV After placing the mandatory data item TLVs into the packet, the implementation would place any supported OPTIONAL data item TLVs. Possible OPTIONAL data item TLVs are: - IPv4 Address - IPv6 Address - Maximum Data Rate - Current Data Rate - Latency - Resources - Relative Link Quality - Credit Window Status - Credit Grant - Credit Request 23. Heartbeat Message A Heartbeat Message is sent by a DLEP participant every N seconds, where N is defined in the "Heartbeat Interval" field of the discovery message. Note that implementations omitting the Heartbeat Interval effectively set the interval to an infinite value, therefore, in those cases, this message would NOT be sent. The message is used by participants to detect when a DLEP session partner (either the modem or the router) is no longer communicating. Participants SHOULD allow some integral number of heartbeat intervals Ratliff et al. Expires March 3, 2013 [Page 34] Internet-Draft DLEP August 2012 (default 4) to expire with no traffic on the router/modem session before initiating DLEP session termination procedures. To construct a Heartbeat message, the initial TLV type value is set to DLEP_PEER_HEARTBEAT (value TBD). The signal TLV is followed by the mandatory data item TLVs: - Identification Note that there are NO OPTIONAL data item TLVs for this message. 24. Link Characteristics Request Message The Link Characteristics Request Message is an OPTIONAL message, and is sent by the router to request that the modem initiate changes for specific characteristics of the link. Since the request specifies a neighbor, it can reference either a real destination (e.g., a remote node), or a logical destination (e.g., a multicast destination) within the network. The Link Characteristics Request message contains either a Current Data Rate (CDR) TLV to request a different amount of bandwidth than what is currently allocated, a Latency TLV to request that traffic delay on the link not exceed the specified value, or both. A Link Characteristics ACK Message is required to complete the request. Implementations are free to define their retry heuristics in event of a timeout. Issuing a Link Characteristics Request with ONLY the MAC Address TLV is a mechanism a peer MAY use to request metrics (via the Link Characteristics ACK) from its partner. To construct a Link Characteristics Request message, the initial TLV type value is set to DLEP_NEIGHBOR_LINK_CHAR_REQ (value TBD). Following the signal TLV are the mandatory Data Item TLVs: Identification Data Item TLV MAC Address data item TLV After placing the mandatory data item TLVs into the packet, the implementation would place any supported OPTIONAL data item TLVs. Possible OPTIONAL data item TLVs are: Current Data Rate - If present, this value represents the NEW (or unchanged, if the request is denied) Current Data Rate in bits per second (bps). Latency - If present, this value represents the maximum desired latency (e.g., it is a not-to-exceed Ratliff et al. Expires March 3, 2013 [Page 35] Internet-Draft DLEP August 2012 value) in milliseconds on the link. 25. Link Characteristics ACK Message The LInk Characteristics ACK message is an OPTIONAL message, and is sent by modems supporting it to the router letting the router know the success or failure of a requested change in link characteristics. The Link Characteristics ACK message SHOULD contain a complete set of metric data item TLVs. It MUST contain the same TLV types as the request. The values in the metric data item TLVs in the Link Characteristics ACK message MUST reflect the link characteristics after the request has been processed. To construct a Link Characteristics Request ACK message, the initial TLV type value is set to DLEP_NEIGHBOR_LINK_CHAR_ACK (value TBD). Following the signal TLV are the mandatory Data Item TLVs: Identification Data Item TLV MAC Address data item TLV After placing the mandatory data item TLVs into the packet, the implementation would place any supported OPTIONAL data item TLVs. Possible OPTIONAL data item TLVs are: Current Data Rate - If present, this value represents the requested data rate in bits per second (bps). Latency - If present, this value represents the NEW maximum latency (or unchanged, if the request is denied), expressed in milliseconds, on the link. 26. Security Considerations The protocol does not contain any mechanisms for security (e.g. authentication or encryption). The protocol assumes that any security would be implemented in the underlying transport (for example, by use of DTLS or some other mechanism), and is therefore outside the scope of this document. 27. IANA Considerations This section specifies requests to IANA. 27.1 Registrations This specification defines: Ratliff et al. Expires March 3, 2013 [Page 36] Internet-Draft DLEP August 2012 o A new repository for DLEP signals, with fifteen values currently assigned. o Reservation of numbering space for Experimental DLEP signals. o A new repository for DLEP Data Items, with eighteen values currently assigned. o Reservation of numbering space in the Data Items repository for experimental data items. o A request for allocation of a well-known port for DLEP communication. o A request for allocation of a multicast address for DLEP discovery. 27.2 Expert Review: Evaluation Guidelines No additional guidelines for expert review are anticipated. 27.3 Signal (Message) TLV Type Registration A new repository must be created with the values of the DLEP signals. Valid signals are: o Peer Discovery o Peer Offer o Peer Offer ACK o Peer Update o Peer Update ACK o Peer Termination o Peer Termination ACK o Neighbor Up o Neighbor Up ACK o Neighbor Down o Neighbor Down ACK o Neighbor Update o Heartbeat o Link Characteristics Request o Link Characteristics ACK It is also requested that the repository contain space for experimental signal types. Ratliff et al. Expires March 3, 2013 [Page 37] Internet-Draft DLEP August 2012 27.4 DLEP Data Item Registrations A new repository for DLEP Data Items must be created. Valid Data Items are: o Identification o DLEP Version o Peer Type o MAC Address o IPv4 Address o IPv6 Address o Maximum Data Rate o Current Data Rate o Latency o Expected Forwarding Time o Resources o Relative Link Quality o Status o Heartbeat Interval/Threshold o Link Characteristics ACK Timer o Credit Window Status o Credit Grant o Credit Request It is also requested that the registry allocation contain space for experimental data items. 27.5 DLEP Well-known Port It is requested that IANA allocate a well-known port number for DLEP communication. 27.6 DLEP Multicast Address It is requested that IANA allocate a multicast address for DLEP discovery messages. 30. Appendix A. 30.1 Peer Level Message Flows 30.1.1 Modem Device Restarts Discovery Router Modem Message Description ==================================================================== Ratliff et al. Expires March 3, 2013 [Page 38] Internet-Draft DLEP August 2012 <-------Peer Discovery--------- Modem initiates discovery ---------Peer Offer-----------> Router detects a problem, sends w/ Non-zero Status TLV Peer Offer w/Status TLV indicating the error. Modem accepts failure, restarts discovery process. <-------Peer Discovery--------- Modem initiates discovery ---------Peer Offer-----------> Router accepts, sends Peer Offer w/ Zero Status TLV w/ Status TLV indicating success. Discovery completed. 30.1.2 Modem Device Detects Peer Offer Timeout Router Modem Message Description ==================================================================== <-------Peer Discovery--------- Modem initiates discovery, starts a guard timer. Modem guard timer expires. Modem restarts discovery process. <-------Peer Discovery--------- Modem initiates discovery, starts a guard timer. ---------Peer Offer-----------> Router accepts, sends Peer Offer w/ Zero Status TLV w/ Status TLV indicating success. Discovery completed. Ratliff et al. Expires March 3, 2013 [Page 39] Internet-Draft DLEP August 2012 30.1.3 Router Peer Offer Lost Router Modem Message Description ==================================================================== <-------Peer Discovery--------- Modem initiates discovery, starts a guard timer. ---------Peer Offer-------|| Router offers availability Modem times out on Peer Offer, restarts discovery process. <-------Peer Discovery--------- Modem initiates discovery ---------Peer Offer-----------> Router detects subsequent discovery, internally terminates the previous, accepts the new association, sends Peer Offer w/Status TLV indicating success. Discovery completed. 30.1.4 Discovery Success Router Modem Message Description ==================================================================== <-------Peer Discovery--------- Modem initiates discovery ---------Peer Offer-----------> Router offers availability -------Peer Heartbeat---------> <-------Peer Heartbeat--------- -------Peer Heartbeat---------> <==============================> Neighbor Sessions <-------Peer Heartbeat--------- -------Peer Heartbeat---------> --------Peer Term Req---------> Terminate Request Ratliff et al. Expires March 3, 2013 [Page 40] Internet-Draft DLEP August 2012 <--------Peer Term Res--------- Terminate Response 30.1.5 Router Detects a Heartbeat timeout Router Modem Message Description ==================================================================== <-------Peer Heartbeat--------- -------Peer Heartbeat---------> ||---Peer Heartbeat--------- ~ ~ ~ ~ ~ ~ ~ -------Peer Heartbeat---------> ||---Peer Heartbeat--------- Router Heartbeat Timer expires, detects missing heartbeats. Router takes down all neighbor sessions and terminates the Peer association. ------Peer Terminate ---------> Peer Terminate Request Modem takes down all neighbor sessions, then acknowledges the Peer Terminate <----Peer Terminate ACK--------- Peer Terminate ACK 30.1.6 Modem Detects a Heartbeat timeout Router Modem Message Description ==================================================================== <-------Peer Heartbeat--------- -------Peer Heartbeat------|| <-------Peer Heartbeat--------- ~ ~ ~ ~ ~ ~ ~ -------Peer Heartbeat------|| <-------Peer Heartbeat--------- Ratliff et al. Expires March 3, 2013 [Page 41] Internet-Draft DLEP August 2012 Modem Heartbeat Timer expires, detects missing heartbeats. Modem takes down all neighbor sessions <-------Peer Terminate-------- Peer Terminate Request Router takes down all neighbor sessions, then acknowledges the Peer Terminate ------Peer Terminate ACK-----> Peer Terminate ACK 30.1.7 Peer Terminate (from Modem) Lost Router Modem Message Description ==================================================================== ||------Peer Terminate-------- Modem Peer Terminate Request Router Heartbeat times out, terminates association. --------Peer Terminate-------> Router Peer Terminate <-----Peer Terminate ACK------ Modem sends Peer Terminate ACK 30.1.8 Peer Terminate (from Router) Lost Router Modem Message Description ==================================================================== -------Peer Terminate--------> Router Peer Terminate Request Modem HB times out, terminates association. <------Peer Terminate-------- Modem Peer Terminate ------Peer Terminate ACK-----> Peer Terminate ACK 30.2 Neighbor Specific Message Flows Ratliff et al. Expires March 3, 2013 [Page 42] Internet-Draft DLEP August 2012 30.2.1 Modem Neighbor Up Lost Router Modem Message Description ==================================================================== ||-----Neighbor Up ------------ Modem sends Neighbor Up Modem timesout on ACK <------Neighbor Up ------------ Modem sends Neighbor Up ------Neighbor Up ACK---------> Router accepts the neighbor session <------Neighbor Update--------- Modem Neighbor Metrics . . . . . . . . <------Neighbor Update--------- Modem Neighbor Metrics 30.2.2 Router Detects Duplicate Neighbor Ups Router Modem Message Description ==================================================================== <------Neighbor Up ------------ Modem sends Neighbor Up ------Neighbor Up ACK-------|| Router accepts the neighbor session Modem timesout on ACK <------Neighbor Up ------------ Modem resends Neighbor Up Router detects duplicate Neighbor, takes down the previous, accepts the new Neighbor. ------Neighbor Up ACK---------> Router accepts the neighbor session <------Neighbor Update--------- Modem Neighbor Metrics . . . . . . . . <------Neighbor Update--------- Modem Neighbor Metrics Ratliff et al. Expires March 3, 2013 [Page 43] Internet-Draft DLEP August 2012 30.2.3 Neighbor Up, No Layer 3 Addresses Router Modem Message Description ==================================================================== <------Neighbor Up ------------ Modem sends Neighbor Up ------Neighbor Up ACK---------> Router accepts the neighbor session Router ARPs for IPv4 if defined. Router drives ND for IPv6 if defined. <------Neighbor Update--------- Modem Neighbor Metrics . . . . . . . . <------Neighbor Update--------- Modem Neighbor Metrics 30.2.4 Neighbor Up with IPv4, No IPv6 Router Modem Message Description ==================================================================== <------Neighbor Up ------------ Modem sends Neighbor Up with the IPv4 TLV ------Neighbor Up ACK---------> Router accepts the neighbor session Router drives ND for IPv6 if defined. <------Neighbor Update--------- Modem Neighbor Metrics . . . . . . . . <------Neighbor Update--------- Modem Neighbor Metrics 30.2.5 Neighbor Up with IPv4 and IPv6 Router Modem Message Description ==================================================================== <------Neighbor Up ------------ Modem sends Neighbor Up with the IPv4 and IPv6 TLVs ------Neighbor Up ACK---------> Router accepts the neighbor session Ratliff et al. Expires March 3, 2013 [Page 44] Internet-Draft DLEP August 2012 <------Neighbor Update--------- Modem Neighbor Metrics . . . . . . . . 30.2.6 Neighbor Session Success Router Modem Message Description ==================================================================== ---------Peer Offer-----------> Router offers availability -------Peer Heartbeat---------> <------Neighbor Up ----------- Modem ------Neighbor Up ACK--------> Router <------Neighbor Update--------- Modem . . . . . . . . <------Neighbor Update--------- Modem Modem initiates the terminate <------Neighbor Down ---------- Modem ------Neighbor Down ACK-------> Router or Router initiates the terminate ------Neighbor Down ----------> Router <------Neighbor Down ACK------- Modem Acknowledgements The authors would like to acknowledge the influence and contributions of Chris Olsen, Teco Boot, Subir Das, Jaewon Kang, Vikram Kaul, Rick Taylor, John Dowdell, Nelson Powell, Bow-Nan Cheng, and Henning Rogge. Normative References [RFC5578] Berry, B., Ed., "PPPoE with Credit Flow and Metrics", Ratliff et al. Expires March 3, 2013 [Page 45] Internet-Draft DLEP August 2012 RFC 5578, February 2010. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Informative References [DTLS] Rescorla, E., Ed,. "Datagram Transport Layer Security", RFC 4347, April 2006. Author's Addresses Stan Ratliff Cisco 170 West Tasman Drive San Jose, CA 95134 USA EMail: sratliff@cisco.com Bo Berry Cisco 170 West Tasman Drive San Jose, CA 95134 USA EMail: boberry@cisco.com Greg Harrison Cisco 170 West Tasman Drive San Jose, CA 95134 USA EMail: greharri@cisco.com Shawn Jury NetApp 7301 Kit Creek Road, Building 2 Research Triangle Park, NC 27709 USA Email: shawn.jury@netapp.com Darryl Satterwhite Cisco 170 West Tasman Drive San Jose, CA 95134 USA Email: dsatterw@cisco.com Ratliff et al. Expires March 3, 2013 [Page 46]