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Re: Re: problem at mae-west tonight?
Rob, In the OSPF community,we faced this same issue a few years back -- the issue being that all members of a single subnet were not reachable either by design or by error and fooling the listeners of the Designated Router (like the route server) into thinking that the nexthops were really reachable. We felt the pains of this especially over virtual circuit networks (Frame Relay, SMDS, and ATM). Temporary workarounds were created. The two better solutions were: 1) Using recommendations in RFC1586,"Guidelines for Running OSPF Over Frame Relay Networks". 2) Using Point-MultiPoint (P-MP) OSPF which is in the latest Internet-Draft of the revision to the RFC1583 (V2 OSPF Spec.). I prefer the P-MP solution because it is an automatic mechanism requiring very little configuration on a network administrators part and keeps the number of routing hops to a minimum. I vote for P-MP as a "Standard" solution for BGP-4 over discontiguous networks. I believe this concept was proposed on this mailing list a few months back. Now that ATM VCs are being used at NAPs with route servers, you'll see more and more of these problems arising...especially at NAPs where there isn't much coordination and cooperation in building and maintaining these high speed, virtual connections. Eural Authement Bay Networks Professional Services ******** > The problem I have with the route server this evening is that I announce > my routes to the route server, and my policy configuration in the route server > reflects that I peer with Netcom, and so the route server tells Netcom how > to reach me. Unfortunately, packets leaving Netcom headed to me at layer 2 > are going into a black hole. To fix this, I've had to dump my peering with > the route server entirely, so that Netcom is only seeing my routes from AGIS > (our transit provider) and not from the route server. Ugh. My fears about > the route server not knowing the status of the layer 2 topology have come true, > and there's no way to fix this that doesn't involve manual intervention. > > -matthew kaufman > [email protected] > > Well, I run gated on a BSDI box for the Hooked MAE West router. I'm thinking about implementing a "pingnouse INTERVAL" option on the peer/group commands in gated, so it will periodically ping next hops received from the route servers and set the nouse bit if the nexthop is unreachable. Any better ideas? It would be nice to come up with a good mechanism for doing 3rd party keepalives that cisco and other router vendors would be willing to implement. Rob - - - - - - - - - - - - - - - - -