Network Working Group T. Boot Internet-Draft Infinity Networks Expires: May 21, 2009 November 17, 2008 Border Router Discovery Protocol (BRDP) Based Routing draft-boot-brdp-based-routing-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of 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 May 21, 2009. Abstract This document specifies a mechanism for routing in multi-homed edge networks. The default gateway routing mechanism is replaced with routing to Border Routers that correspond with the source address of the packets. Boot Expires May 21, 2009 [Page 1] Internet-Draft BRDP Based Routing November 2008 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Problems with default gateway routing . . . . . . . . . . . . . 3 3. Default gateway routing replaced with BRDP Based Routing . . . 4 4. Support for IPv4 . . . . . . . . . . . . . . . . . . . . . . . 5 5. IANA considerations . . . . . . . . . . . . . . . . . . . . . . 5 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 8.1. Normative References . . . . . . . . . . . . . . . . . . . 5 8.2. Informative References . . . . . . . . . . . . . . . . . . 6 Appendix A. Change Log From Previous Version . . . . . . . . . . . 6 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6 Intellectual Property and Copyright Statements . . . . . . . . . . 7 Boot Expires May 21, 2009 [Page 2] Internet-Draft BRDP Based Routing November 2008 1. Introduction With the growth of the Internet, the routing table in the Internet Default Free Zone (DFZ) is becoming unacceptably large. One of the reasons is usage of Provider Independent (PI) Address blocks in edge networks. A remedy is encouragement of Provider Aggregatable (PA) Addresses. Unfortunately, PA addresses and multi-homing may introduce some problems if not carefully planned and configured [RFC3704]. In a stable network, multi-homing with PA addresses can be supported by configuring routing, tunneling, filtering or other mechanisms. In a more dynamic world, this is less practical and needs improvement. In a MANET [RFC2501], manual configuration is infeasible. The Border Router Discovery Protocol (BRDP) [I-D.boot-autoconf-brdp] provides a mechanism for Address Autoconfiguration in ad hoc networks and may support automatic renumbering. In addition, a mechanism is needed for ensuring that traffic is directed to a Border Router that corresponds with the source address. This will circumvent problems with ingress filtering, as described in [RFC5220] section 2.1.2. BRDP Based Routing provides a mechanism for packet delivery to Border Routers that correspond with the source addresses of the packets. This mechanism is applied for traffic that is not destined for interior nodes of the edge network. It replaces the default route mechanism. The BRDP Based Routing mechanism also provides basic support for load distribution over multiple Border Routers. More advanced load balancing can be provided for multi-homed hosts, provisioned with transport layer facilities that utilize multi-homing. 2. Problems with default gateway routing Usually, the nexthop selection is based on the destination address. In case of default gateway routing and multiple exit routers to multiple providers, the source has no influence on what exit router is used. In case of ingress filtering and lack of a mechanism to redirect packets to exit routers that correspond to the source address, packets may be dropped. This default gateway routing behavior blocks incremental enhancement of the Internet, e.g. through the addition of support for more dynamic networks and / or host based load distribution mechanisms. In a MANET, it also also prevents the use of make-before-break [RFC3753] mechanisms. Boot Expires May 21, 2009 [Page 3] Internet-Draft BRDP Based Routing November 2008 3. Default gateway routing replaced with BRDP Based Routing Default gateway based routing for IPv4 is defined in [RFC1812], section 5.2.4.3: (5) Default Route: This is a route to all networks for which there are no explicit routes. It is by definition the route whose prefix length is zero. With BRDP Based Routing, another type of route is introduced: (6) BRDP Route: This is a route to all networks for which there are no explicit routes, and a default route is not used. The nexthop IP address is found by means of a Border Router Information Cache (BRIO-Cache) lookup based on the source address and, if a matching BRIO-Cache entry is found, a subsequent FIB lookup based on the selected Border Router address. Note that route types (3) and (4) are not defined in RFC1812. BRDP Based Routing can be turned on and off with the existence of a default route in the IGP. This switch function might be useful in migration scenarios towards BRDP Based Routing. The Border Router should run the IGP on the interface with the BRDP advertized Border Router address. In the edge network, all interior routers should run BRDP and BRDP Based Routing. All interior routers will have a BRIO-Cache [I-D.boot-autoconf-brdp] with information for selecting Border Routers as exit points to the Internet. A BRIO-Cache entry contains a Border Router address and a summary prefix assigned to that Border Router. BRIO-Cache lookup follows the longest-match rule. Forwarding is solely based on FIB lookups, the nexthop IP address is found either by a FIB lookup with the destination address or by a FIB lookup with the address of the Border Router that corresponds with the source address. If the nexthop IP address lookup fails, the packet is discarded. Boot Expires May 21, 2009 [Page 4] Internet-Draft BRDP Based Routing November 2008 4. Support for IPv4 BRDP-based Address Autoconfiguration is designed for IP version 6. Support for IP version 4 will be taken into consideration. 5. IANA considerations This document has no actions for IANA. 6. Security Considerations BRDP Based Routing depends on BRDP and the IGP used. BRDP depends on security mechanisms provided by ND [RFC4861]. ND can be secured by SeND [RFC3971]. IGPs are assumed to have their own security mechanisms. More research on security issues for BRDP Based Routing is needed. 7. Acknowledgments BRDP is inspired by MANEMO technology; thanks to all who contributed to it. Thanks to Ran Atkinson, who guided me towards a BRDP Based Routing mechanism that does not rely on routing headers or encapsulation. And thanks to Ronald in 't Velt for reviewing. 8. References 8.1. Normative References [RFC1812] Baker, F., "Requirements for IP Version 4 Routers", RFC 1812, June 1995. [RFC3971] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure Neighbor Discovery (SEND)", RFC 3971, March 2005. [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, September 2007. [I-D.boot-autoconf-brdp] Boot, T., "Border Router Discovery Protocol (BRDP) based Address Autoconfiguration", draft-boot-autoconf-brdp-01 (work in progress), October 2008. Boot Expires May 21, 2009 [Page 5] Internet-Draft BRDP Based Routing November 2008 8.2. Informative References [RFC2501] Corson, M. and J. Macker, "Mobile Ad hoc Networking (MANET): Routing Protocol Performance Issues and Evaluation Considerations", RFC 2501, January 1999. [RFC3704] Baker, F. and P. Savola, "Ingress Filtering for Multihomed Networks", BCP 84, RFC 3704, March 2004. [RFC3753] Manner, J. and M. Kojo, "Mobility Related Terminology", RFC 3753, June 2004. [RFC5220] Matsumoto, A., Fujisaki, T., Hiromi, R., and K. Kanayama, "Problem Statement for Default Address Selection in Multi- Prefix Environments: Operational Issues of RFC 3484 Default Rules", RFC 5220, July 2008. Appendix A. Change Log From Previous Version o 00: Initial Document. Author's Address Teco Boot Infinity Networks B.V. Elperstraat 4 Schoonloo 9443TL The Netherlands Email: teco@inf-net.nl Boot Expires May 21, 2009 [Page 6] Internet-Draft BRDP Based Routing November 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Boot Expires May 21, 2009 [Page 7]