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Source/Destination Routing

Source/Destination Routing. Fred Baker Cisco Systems. Problem History. Identified as a requirement soon after the deployment of BCP 38 Discussed as an objective in shim6 context RFC 3704 Marcelo Bagnulo research (2003) Various efforts centering on homenet requirements

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Source/Destination Routing

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  1. Source/Destination Routing Fred Baker Cisco Systems

  2. Problem History • Identified as a requirement soon after the deployment of BCP 38 • Discussed as an objective in shim6 context • RFC 3704 • Marcelo Bagnulo research (2003) • Various efforts centering on homenet requirements • Troan & Colitti: draft-troan-homenet-sadr • Chroboczek& Boutier: draft-boutier-homenet-source-specific-routing • Baker: draft-baker-ipv6-ospf-dst-src-routing and draft-baker-ipv6-isis-dst-src-routing • Yang & Xu: draft-xu-homenet-traffic-class, draft-xu-homenet-twod-ip-routing

  3. RFC 3704 • Savolaand Baker • Suppose a session is opened up to a remote location in a multihomed network • Suppose the default route takes it to the wrong egress • ISP A’s source address but routed to ISP B • Wouldn’t it be nice if the packet got to the right egress somehow? BCP 38 Filter ISP B ISP A Ideal Route

  4. USE Cases

  5. Homenet’s first concern • A home with • one router, • two upstreams, and • a PA Prefix from each • Is there a way to systematically have it get packets to the right upstream network? • Without manual configuration? • Might be solved from DHCPv6 IA_PD ISP B ISP A

  6. But residential routers usually have one upstream… • A home with • multiple routers, • two upstreams, and • a PA Prefix from each • Is there a way to systematically have it get packets to the right egress router? • Without manual configuration? • If there is one LAN, simple solution is for host to give packet using a source prefix to the router from which it learned a prefix ISP B ISP A

  7. Multi-LAN case • A home with • Multiple routers, • Multiple LANs • Two upstreams, and • A PA Prefix from each • Is there a way to systematically have it get packets to the right egress router? • Without manual configuration? • If there is more than one LAN, this begins to call for a routing protocol: • Separate routing for default route by source prefix ISP A ISP B

  8. NTT B-FLETS Case • What if they are not general use ISPs? • NTT B-FLETS is a video service. • It doesn’t offer general ISP services • Source Prefix: • Traffic to consumer ISP must use ISP’s source prefix • Traffic to B-FLETS must use B-FLETS-assigned source prefix • Routing: • Although B-FLETS does not provide general Internet access, it advertises a default route • Ideally, that changes to advertising a route to B-FLETS ISP B-Flets

  9. Generalizing • We need the ability to advertise and use a route • To a destination prefix (could be ::/0) • From a source prefix (could be ::/0) • Ambiguity issues • There are a number of potentially ambiguous cases • Resolution similar to longest-match rule • Use the FIB entry with the longest destination match that also matches the source

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