Ray, > I have read this draft and find it useful. > >> A routing entry may have both (S, D) paths and (*, D) paths. The > longest match wins > > Section 5 seems to suggest SADR is just a tie breaker applied to the > subset of equal length D routes, but I think you probably should be more > specific on the phrase "longest match" in this sentence, as there are 2 > length comparisons (one on D and one on S)
yes, right now we say: "First a longest match lookup is done in the routing table for the destination address, then for the resulting set a longest matching lookup is done for the source address." what if we also included some RIB entry examples? e.g. ::/0 (route) 2001:db8::/56 -> NH1 (path #1) 2001:db9::/56 -> NH2 (path #2) -> NH#3 (path #3) would that make it clearer? > Section 6.2. > > During autoconfig, if the prefix is delegated to other Homenet routers > on a hop by hop basis, the Homenet router receiving a new prefix could > indeed install a default SADR route for (parent_prefix/x,0:/0) -> the > upstream delegating router. So in this case your requirement 2 to > strongly couple autoconfiguration and routing would not seem onerous. right, in that case the parent prefix wouldn't really be the aggregate prefix though, and not identify the border exit. in a strict routed hierarchy then I guess you wouldn't need SADR. > But alternatively, if the delegation of prefixes within Homenet occurs > via a mechanism like DHCP PD, the receiving router could instead install > a default SADR route (parent_prefix/x,0:/0) -> Homenet BR DHCP PD source > address, and then recurse the standard unicast routing table to find the > appropriate next hop toward the Homenet BR. This is a trick that works > very well in BGP networks (with next BGP hop being a software/loopback > interface of the AS egress router that is always up and stable, combined > with an IGP containing just the loopback addresses of the BGP speaking > AS egress routers) yes, now we tie the aggregate prefix and the advertising border router using the router-id. if the border router had a global address, that was included in the aggregate route advertisement as well as the external route advertisements, we could use that instead. it would certainly make the routing tables more clearer and more explicit. > In which case there's no requirement for a hard link between the routing > protocol and the prefix autoconfiguration mechanism, and thus no > requirement to update the IGP to carry SADR routes, which I think is > potentially a big win. that would be a big win, but I don't quite see how you avoid the hard link? given that border routers may or may not advertise a default route, and may also advertise more specifics... cheers, Ole _______________________________________________ homenet mailing list [email protected] https://www.ietf.org/mailman/listinfo/homenet
