Source Address Selection for IPv6 FUJIKAWA Kenji Internet-Draft ROOT Inc. Expires: May 12, 2008 November 2007 Source Address Selection Just by Routing Information for IPv6 draft-fujikawa-ipv6-src-addr-selection-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 January 2, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract This document describes a problem problem of at source address selection Rule 8. in RFC3484. FUJIKAWA Expires May 12, 2008 [Page 1] Internet-Draft Source Address Selection for IPv6 November 2007 1. A Problem of at Source Address Selection Rule 8. in RFC3484 In RFC3484[RFC3484], the source addresss selection guidlines when multihoming are shown. However, according to them, a problem occur that a host cannot select the best path. Rule 8 in 5. Source Address Selection in RFC3434 says: Rule 8: Use longest matching prefix. If CommonPrefixLen(SA, D) > CommonPrefixLen(SB, D), then prefer SA. Similarly, if CommonPrefixLen(SB, D) > CommonPrefixLen(SA,D), then prefer SB. Consider a network shown in the below: +---+ |CN | +-+-+ | 2001:db8:2001::CN | +---+---+2001:db8:2000:/36 | | +---------+ ISP2 | +----+ +----+ | | +--+ISP5+--+ISP4| | +-------+ +----+ +-+--+ | | +---+---+2001:db8:1000::/36 +------++ | | | | | ISP1 +-------------------+ ISP3 | | | | |2001:db8:3000::/36 +---+---+ +---+---+ | | | | +------------+ +------------+ 2001:db8:1000::R| |2001:db8:3000::R ++-++ 2001:db8:1001::/48| R |2001:db8:3001::/48 +-+-+ | fe80::R | 2001:db8:1001:1:EN | 2001:db8:3001:1:EN +-+-+ | EN | +---+ In the network, - Each of ISP1, ISP2, and ISP3 has an address space, 2001:db8:1000::/36, 2001:db8:2000::/36, and 2001:db8:3000::/36, FUJIKAWA Expires May 12, 2008 [Page 2] Internet-Draft Source Address Selection for IPv6 November 2007 respectively. - Correspondent node CN belongs to ISP2, and has an address 2001:db8:2001::CN. - Router R is multihomed to ISP1 and ISP3, and distributes address spaces below such as 2001:db8:1001::/48 and 2001:db8:3001::/48. - End node EN is assigned two addresses, 2001:db8:1001:1:EN and 2001:db8:3001:1:EN. Here, in the IPv6 address notation, CN, R, and EN indicates 64bit Interface ID's. According to Rule 8, by means of the longest match method, 2001:db8:3001:EN is selected as the source address of a packet towarding from CN to EN. Therefore, - For the purpose of avoiding the source address filtering, policy routing or etc. is required in order to direct a packet to ISP3. - The route becomes roundabout passing throug ISP3. Author's Address FUJIKAWA Kenji ROOT Inc., Kyoto Information Laboratory 59 Minami-yonnotsubo-cho, Iwakura, Sakyo-ku, Kyoto 606-0033, Japan Phone: +81-3-5436-8380 (Ext. 1593) Email: fujikawa@root-hq.com FUJIKAWA Expires May 12, 2008 [Page 3] Internet-Draft Source Address Selection for IPv6 November 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). 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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