INTERNET-DRAFT F. Templin SRI International Expires 31 July 2002 31 January 2002 Fast Convergence Extension for ISATAP Router Discovery draft-templin-ngtrans-isatapext-00.txt Abstract This document specifies an optional extension to the Intra-Site Automatic Tunnel Addressing Protocol [ISATAP] to provide fast convergence (i.e., fast router discovery). ISATAP is a transition mechanism that enables incremental deployment of IPv6 by treating the site's IPv4 infrastructure as a Non-Broadcast Multiple Access (NBMA) link layer. The router discovery mechanisms proposed by ISATAP are well suited for allowing hosts to discover routers on fixed networks, i.e, networks with relatively static links and nodes. But, their slow periodic polling properties do not support timely router discovery for nodes in dynamic networks, e.g., wireless networks in which mobile nodes "visit" only for brief periods of time. The optional extension proposed by this draft may be useful for ISATAP deployments that require fast convergence. Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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. Templin Expires 31 July 2002 [Page 1] INTERNET-DRAFT Fast Convergence for ISATAP 31 January 2002 Copyright Notice Copyright (C) The Internet Society (2002). All Rights Reserved. 1. Introduction This document specifies an optional extension for [ISATAP] that sup- ports fast convergence (i.e, fast discovery of on-link routers). The extension employs a subset of the multicast mechanisms specified by [6OVER4] to augment the NBMA mechanisms specified by [ISATAP]. 2. Applicability Statement - provides fast convergence for [ISATAP] deployments on dynamic networks, e.g., in a Mobile Ad-Hoc Network [MANET] - may provide benefits for fixed networks, e.g., Router Advertisement consistency verification. - augments (but does not replace) the mechanisms specified in [ISATAP] - best suited for networks with full/partial deployment of IPv4 multicast 3. Terminology The terminology of [IPv6] and [ISATAP] apply to this document. The following additional term is defined: 6OVER4/ISATAP pseudo-interface: a virtual attachment to an ISATAP interface that maps IPv6 multicast to IPv4 multicast addresses exactly as specified in [6OVER4,6] 4. Transmission of IPv6 Packets on 6OVER4/ISATAP Pseudo Interfaces Nodes in networks that deploy [ISATAP] MAY OPTIONALLY attach a 6OVER4/ISATAP pseudo-interface to any of their ISATAP interfaces. The 6OVER4/ISATAP pseudo-interface uses IPv6 link-local address of the attaching ISATAP interface and the specification for transmission of IPv6 packets found in [ISATAP,4]. The sending rules and address map- ping in [ISATAP,4.4] are not used, however; the address mapping specification for multicast in [6OVER4,6] is used instead. The Templin Expires 31 July 2002 [Page 2] INTERNET-DRAFT Fast Convergence for ISATAP 31 January 2002 following additional sending rule is specificed: - the IPv6 next-hop address for packets sent on the 6OVER4/ISATAP pseudo-interface MUST be 'All-Nodes Multicast' On networks that deploy ISATAP and a full or partial native IPv4 mul- ticast capability, this optional mechanism allows ISATAP routers to send periodic unsolicited multicast Router Advertisement messages and for ISATAP hosts to process any such Router Advertisements received as specified below: 5. Router Specification Advertising ISATAP interfaces of routers behave exactly the same as [ISATAP,5.2.3]. Routers MAY OPTIONALLY configure a 6OVER4/ISATAP pseudo interface on any of their ISATAP interfaces for the sole pur- pose of sending periodic unsolicited multicast Router Advertisements, exactly as specified in [DISC,6.2.4]. The configuration variables in [DISC,6.2.1] are used. 6. Host Specification Hosts behave exactly the same as [ISATAP,5.2.4]. Hosts MAY OPTIONALLY configure a 6OVER4/ISATAP pseudo interface on any ISATAP interface for the sole purpose of receiving periodic unsolicited multicast Router Advertisements. The 6OVER4/ISATAP pseudo-interface presents received multicast Router Advertisements to its attaching ISATAP interface, which processes them exactly as specified in [ISA- TAP,5.2.4]. 7. Deployment Considerations This optional mechanism SHOULD only be used on networks with a full or partial native IPv4 multicast routing deployment. Network adminis- trators SHOULD configure values for the variables found in 'Router Specification' to provide an appropriate tradeoff between fast con- vergence and control traffic overhead based on characteristics of the underlying network. 8. IANA considerations No assignments by IANA are required beyond those in [6OVER4][ISATAP]. Templin Expires 31 July 2002 [Page 3] INTERNET-DRAFT Fast Convergence for ISATAP 31 January 2002 9. Security considerations Security considerations are the same as for [ISATAP,8]. Acknowledgements Some of the ideas presented in this draft were derived from work at SRI with internal funds and contractual support. Government sponsors who supported the work include Monica Farah-Stapleton and Russell Langan from U.S. Army CECOM ASEO, and Dr. Allen Moshfegh from U.S. Office of Naval Research. Within SRI, Dr. Mike Frankel, J. Peter Mar- cotullio, Lou Rodriguez, and Dr. Ambatipudi Sastry supported the work and helped foster early interest. The authors recognize that ideas similar to those in this document may have already been presented by others and wish to acknowledge any other such contributions. Normative References [6OVER4] Carpenter, B. and C. Jung, "Transmission of IPv6 over IPv4 Domains without Explicit Tunnels", RFC 2529. [DISC] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, December 1998. [IPV6] Deering, S., and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460. [ISATAP] Templin, F., Gleeson, T., Talwar, M., and D. Thaler, "Intra-Site Automatic Tunnel Addressing Protocol (ISATAP)", draft-ietf-ngtrans-isatap-03.txt, (work-in-progress). Informative References [MANET] Corson, S. and J. Macker, "Mobile Ad hoc Networking (MANET): Routing Protocol Performance Issues and Evaluation Considerations", RFC 2501. Templin Expires 31 July 2002 [Page 4] INTERNET-DRAFT Fast Convergence for ISATAP 31 January 2002 Authors Addresses Fred L. Templin SRI International 333 Ravenswood Ave. Menlo Park, CA 94025, USA Phone: (650)-859-3144 Email: templin@erg.sri.com Intellectual Property Placeholder for IPR statement. Templin Expires 31 July 2002 [Page 5]