IPNG Working Group Jun Kyun Choi Internet Draft Gyu Myoung Lee Document: draft-choi-ipv6-signaling-00.txt Ki Young Jung Expiration Date: April, 2002 ICU November 2001 The Features of IPv6 Signaling Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC-2026. 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. Abstract In this memo, we describe the features of IPv6 signaling protocol. We also discuss the related issues and the need of new signaling. We will explain the implementation issues in some detail. Conventions 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 RFC-2119. Choi et al [Page 1] Internet Draft The Features of IPv6 Signaling November 2001 Table of Contents 1. Introduction .............................................. 2 2. Features and Considerations of IPv6 Signaling ............. 3 2.1. Features ................................................ 3 2.2. Considerations .......................................... 4 3. Implementations Issues .................................... 6 3.1. Using Router Alert Option ............................... 6 3.2. Using Internet Signaling Message Protocol (ISMP) ........ 7 4. Other Issues .............................................. 8 5. IANA Considerations ....................................... 8 6. Security Considerations ................................... 9 References ................................................... 9 Author's Addresses ........................................... 10 1. Introduction IPv6 technology is deployed in many fields. But to provide fine QoS in IPv6 networks, there SHOULD be some signaling mechanisms. So far, IETF have standardized the RSVP [RFC 2205] signaling to support this, but that mechanism is weak for the scalability. With regard to DiffServ [RFC 2475] model, it can solve the scalability problem. But without signaling, it cannot provide the fine QoS. In other field, the MPLS [RFC 3031] with aggregated flow labeling and signaling, such like CR-LDP and RSVP-TE, is a good solution for traffic engineering. Therefore it can accommodate the killer application such as VPN services. To adapt the label switching concept and QoS functionalities, there are some methodologies like IPngLS(IP next generation Label Switching) using flow label field in IPv6 basic header. Someone may want to make use of existing signaling mechanism and the others may prefer new signaling mechanism. We describe the features of new IPv6 signaling to use and distribute the information of flow label and other QoS related parameters. The main issues we are to address here is the label distribution method and QoS information delivering method adopted with IPv6 header including IPv6 extension headers. In order to do this, we suggest the methods how to notify the existence of signaling information to the routers on the path. And the effects of each choice will be discussed. Choi et al [Page 2] Internet Draft The Features of IPv6 Signaling November 2001 2. Features and Considerations of IPv6 Signaling 2.1. Features o QoS parameters Information with QoS controlling is important context of signaling packet. With aggregated flow concept, IPv6 native signaling can provide finer QoS granularity than DiffServ model, and more scalable than IntServ model. o Resource Reservation The key role of signaling is to allocate and reserve the network resource for the purpose of meeting end-to-end QoS requirements along the entire path. The signaling protocol MUST be able to deal with such resource allocation requests. o Priority Flow Control Each node has many flows with different priority of various data rates and QoS requirements. These flows are classified and scheduled with the capability of making intelligent decisions on how resource allocation SHOULD be controlled. o Explicit route In IPv6 specification, there is a route extension header to use explicit route. Explicit route is important for traffic engineering in IPv6 networks, so we can use of this option header. In doing so, signaling packet specify the route with route extension header and data packet is just switched according to flow label in each router on the path specified with signaling packet. There is already ROUTE object in RSVP-TE specification [RSVP-TE 09]. We will discuss it in section 2.2. o Scalability The performance of the signaling SHOULD not largely depend on the scale of the network to which IPv6 is applied (e.g. the number of nodes, the number of physical links etc). The signaling function SHOULD keep constant performance as much as possible regardless of network size. Aggregating flows can reduce resource allocation and runtime management overhead o Flow Label Information Distribution To make use of flow label field as mentioned in [IPNGLS 00] and identify the flow label between the routers on specific path, label- binding information SHOULD be delivered between the related routers. The related routers are on the path of the flow. Choi et al [Page 3] Internet Draft The Features of IPv6 Signaling November 2001 Label value is only meaningful between a pair of routers. And the label value is predetermined before forwarding data packet along the path. o Label Stacking In [IPNGLS 00], label stacking concept is addressed. To enable the label stacking, the signaling is defined to notify the stacking information. But we don't consider the concept in this version. 2.2. Considerations Besides of features of signaling, we must consider the following issues to make the signaling mechanism. o Easy to implements There are two aspects related with this issue. First, we can consider the compatibility of the new signaling with existing signaling. So the implementation can be done with minimum modification of previous architecture and components. Second we can omit some functions of previous signaling so that we just make a light-weight signaling mechanism. We are still studying about this carefully because it makes some effects with other various factors such like the capabilities of this new signaling and the signaling translation between two heterogeneous AS's. We can think above two factors simultaneously and SHOULD make some trade-off. o No problems with non-implemented nodes To be gradually deployed, we can consider the situation of mixed nodes that some implement the signaling and the other don't implement it. Usually signaling mechanisms are ignoring that node and just forward it. o Make use of IPv6 features It is another implementation related issues. IPv6 have a many features to make use of that to provide some new functions. For example, one can want to use the IPv6 Routing Option header to send signaling packet along the desired path rather than the shortest path. This is reasonable because the IPv6 routers may be implement routing option header processing component so we can use that without any additional functional implementations. Also we can think about the hop-by-hop header to notify routers that the packets have some signaling and reservation information. These things are already considered in other signaling mechanism. That means we can use the IPv6 native features or don't use of them. There is another view- point related with this. If the same information is transferred with Choi et al [Page 4] Internet Draft The Features of IPv6 Signaling November 2001 IPv6 header and payload, there may exist the consistency problems. So some people want to make one of choices, not both of them. o QoS parameters This signaling will apply the QoS parameter per aggregated flow. To make use of this, state of QoS information SHOLD be maintained per aggregated flow. Also the adding and deleting of a flow with respect to the aggregated flow SHOULD be carefully managed. An aggregated flow is not just used for label-related switching, but also used for classification information in routers on path. So the QoS parameter information SHOULD be stored in the router with the information of relation with an aggregated flow identifier(s). o Mobility support To provide the QoS in mobile environment, we SHOLD consider the mobility of nodes and dynamic behavior of related flows. In signaling, we are concerning two problems. First the flow management can be considered with per aggregated flow or per flow. In some point, snapshot of network can be described with many aggregated flows and related QoS management. But as time goes, some flow of mobile node is depart one aggregated flow and join the other aggregated flow. Second the support of micro mobility issues. To make use of old flow related resources as much as possible, we should define Nearest Common Router (NCR) and provide the finding mechanism. This work is under working in [RSVP -MIPv6]. We just consider the need of modification or adaptation of that mechanism in our work. o Inter-operation with other QoS-supporting networks In this version, we cannot consider this issue. Choi et al [Page 5] Internet Draft The Features of IPv6 Signaling November 2001 3. IPv6 Signaling Implementation Issues This section is going to discuss two methods for carrying the signaling messages such as RSVP-TE within IPv6 datagrams. Other signaling messages that use TCP or UDP like CR-LDP, SIP are discussed in section 4. 3.1. Using Router Alert Option Router alert option [RFC 2711] within the IPv6 Hop-by-Hop option header has the semantic "routers should examine the datagram more closely". Using this option, IPv6 datagrams containing signaling messages are indicated and taken actions. The router alert option has the following format: +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 0 0|0 0 1 0 1|0 0 0 0 0 0 1 0| Value (2 octets) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ length = 2 The first three bits of the first byte are zero and the value 5 in the remaining five bits is the Hop-by-Hop Option Type number. [RFC 2460] specifies the meaning of the first three bits. By zeroing all three, this specification requires that nodes not recognizing this option type should skip over this option and continue processing the header and that the option must not change en route. There MUST only be one option of this type, regardless of value, per Hop-by-Hop header. Value: A 2 octet code in network byte order with the following values: 0 Datagram contains a Multicast Listener Discovery message [RFC 2710]. 1 Datagram contains RSVP message. 2 Datagram contains an Active Networks message. 3-65535 Reserved to IANA for future use. Alignment requirement: 2n+0 Values are registered and maintained by the IANA. We suggest the new value (= 3) for RSVP-TE messages. The value 3 is REQUIRED the approval of IETF and SHOULD be assigned by IANA. Other signaling messages MAY be added. In this case, the value for new signaling message SHOULD be assigned by IANA. Choi et al [Page 6] Internet Draft The Features of IPv6 Signaling November 2001 The described method has some advantages and disadvantages. It is not necessary to implement the new protocol for signaling. The existing signaling message is used without change. However, all IPv6 datagrams containing a signaling message MUST contain this option within the IPv6 Hop-by-Hop Option Header of such datagrams. The additional option header is redundant. 3.2. Using Internet Signaling Message Protocol (ISMP) We propose the new protocol, Internet Signaling Message Protocol (ISMP), for signaling such as the ICMPv6 [RFC 2463]. ISMP is used to carry signaling messages. Every ISMP message is preceded by an IPv6 header or by more IPv6 extension headers. The ISMP message is identified by a Next Header value in the immediately preceding header. The ISMP messages have the following general format: +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Version| Traffic Class | Flow Label | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Payload Length | Next Header | Hop Limit | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | | + Source Address + | | + + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | + + | | + Destination Address + | | + + | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + + | ISMP Message Body | + (signaling message) + Version 4-bit Internet Protocol version number = 6. Traffic Class 8-bit traffic class field. Flow Label 20-bit flow label. Choi et al [Page 7] Internet Draft The Features of IPv6 Signaling November 2001 Payload Length 16-bit unsigned integer. Length of the IPv6 payload, i.e., the rest of the packet following this IPv6 header, in octets Next Header 8-bit selector. Identifies the type of signaling message immediately following the IPv6 header. Uses the same values as the IPv4 Protocol field [RFC 1700 et seq.]. Hop Limit 8-bit unsigned integer. Decremented by 1 by each node that forwards the packet. The packet is discarded if Hop Limit is decremented to zero. Source Address 128-bit address of the originator of the packet. Destination Address 128-bit address of the intended recipient of the packet (possibly not the ultimate recipient, if a Routing header is present). For this method, we MUST assign the new Next Header value of IPv6 header. Currently, RSVP is already assigned the value 46 decimal in [RFC 1700]. For example, if the Next Header value of IPv6 header is 46 decimal the following ISMP message is RSVP message. The Next Header value of other unassigned signaling messages SHOULD be assigned by IANA. Compared with the method using router alert option, this method is very simple because of no additional extension header. Therefore, the complexity of processing is reduced but this new function MUST be implemented within IPv6 header. 4. Other Issues We SHOULD consider the interworking issues for transparent transport of signaling messages between IPv4 and IPv6 network. The mechanisms that carry application-level signaling (ex. SIP) and other signaling (ex. CR-LDP) using TCP or UDP SHOULD also be considered. One of way to do that is that IP header bears the information about the existence of specific signaling packet in the payload. The benefit of this concept is that a router on the path can make decision whether the signaling information is useful for itself and then, consequently, it can check the payload without processing it in upper layer (ex. TCP or UDP). So we are on studying to implement our idea over the existing signaling protocols. Choi et al [Page 8] Internet Draft The Features of IPv6 Signaling November 2001 5. IANA Considerations The value field described in Section 3 SHOULD be registered and maintained by IANA. The New values SHOULD be to be assigned via IETF Consensus as defined in [RFC 2434]. 6. Security Considerations This document does not have any security concerns. The security requirements using this document are described in the referenced documents. References [RFC 1700] J. Reynolds et al.. "Assign Numbers", RFC 1700, October 1994 [RFC 2205] R. Braden, Ed. et al.. "Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification", RFC 2205, September 1997 [RFC 2434] T. Narten, et al.. "Guidelines for Writing an IANA Considerations Section in RFCs", RFC 2434, October 1998 [RFC 2463] A. Conta, et al.. "Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification", RFC 2434, December 1998 [RFC 2475] S. Blake, et al.. "An Architecture for Differentiated Services", RFC 2475, December 1998 [RFC 2710] S. Deering, et al.. "Multicast Listener Discovery (MLD) for IPv6", RFC 2710, October 1999 [RFC 2711] C. Partridge, et al.. "IPv6 Router Alert Option", RFC 2711, October 1999 [RFC 3031] E. Rosen, et al.. "Multiprotocol Label Switching Architecture", RFC 3031, January 2001 [RSVP-TE 09] Daniel O. Awduche et al.. "RSVP-TE: Extensions to RSVP for LSP Tunnels-09", Internet Draft, August 2001 [IPNGLS 00] V. Roesler et al.. "IPNGLS - IP Next Generation Label Switching-00", Internet Draft, September, 2001 [RSVP-MIPv6 00] Charles Qi Shen, et al.. "An Interoperation Framework for Using RSVP in Mobile IPv6 Networks-00", Internet Draft, July 2001 Choi et al [Page 9] Internet Draft The Features of IPv6 Signaling November 2001 Author's Addresses Jun Kyun Choi Information and Communications University (ICU) 58-4 Hwa Ahm Dong, Yusong, Taejon Korea 305-732 Phone: +82-42-866-6122 Email: jkchoi@icu.ac.kr Gyu Myoung Lee Information and Communications University (ICU) 58-4 Hwa Ahm Dong, Yusong, Taejon Korea 305-732 Phone: +82-42-866-6231 Email: gmlee@icu.ac.kr Ki Young Jung Information and Communications University (ICU) 58-4 Hwa Ahm Dong, Yusong, Taejon Korea 305-732 Phone: +82-42-866-6182 Email: jjungki@icu.ac.kr Full Copyright Statement "Copyright (C) The Internet Society (date)". All Rights Reserved. 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Document: draft-ietf-ipv6-signaling-00.txt Expiration Date: April 2002 Choi et al [Page 10]