On Jan 9, 2014, at 7:09 AM, John R Levine <johnl@xxxxxxxxx> wrote: > I was at a meeting talking to ops people from some large ISPs, who tell me that when they tell their large customers about BCP 38, the customers say forget it, because they're multihomed. I gather the situation is typically that the customer has multiple address ranges, say from providers A and B. Normally traffic from range A goes out through provider A, and vice-versa, except sometimes when it doesn't. Sometimes it's failover, or it may be deliberate asymmetic routing. The customers may not be running BGP, or if they do, they don't want to announce range A to provider B for business reasons I don't entirely understand but that are not going away. > > The ISPs tell me that the customers are often ISPs themselves, so there are lots of address ranges, far more than anyone could track manually even if they wanted to. > > I see BCP 84, which is now ten years old. The ISPs are aware of it, but it doesn't seem to have done the trick. I can think of some hacks to pseudo-announce ranges for filtering purposes, but surely I am not the only person to have noticed this problem. What have people done to address this issue?* I figure the first thing to do is to understand what's failed before. There are some drafts you may find interesting: http://tools.ietf.org/html/draft-boutier-homenet-source-specific-routing http://tools.ietf.org/html/draft-troan-homenet-sadr http://tools.ietf.org/html/draft-baker-ipv6-isis-dst-src-routing http://tools.ietf.org/html/draft-baker-ipv6-ospf-dst-src-routing http://tools.ietf.org/html/draft-baker-rtgwg-src-dst-routing-use-cases http://tools.ietf.org/html/draft-xu-homenet-traffic-class http://tools.ietf.org/html/draft-xu-homenet-twod-ip-routing Homenet has been looking at this from the perspective of egress routing in residential multihoming. I have been looking at it more from source/destination routing in OSPF/IS-IS, for which "egress routing" and "residential multihoming" are special cases.
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