> > > Hi Richard, > Could you run a bgp session on Router B ? I had to do this once for > a customer because we had layer 3 switches on the edge with routing. I > configured 2 BGP sessions at the customer's router. The first session was > between Customer C and Router B. I only sent the default route to the > customer. The next session was ebgp multihop between Router A and Customer > C with full routing. I did allow the customer to announce the /30 to > Router B just so Router A could learn the return path or you could just > static route the /30 from Router A > > Now if the link Breaks between Router B and Customer C BGP will drop both > sessions. > > Thanks > Jim Gonzalez > > When Router A redistributes external routes to OSPF, it sets the next hop to itself. All the routers include Router B in the AS sends to traffic to Router A which sends to Router B and causes a loop. The root cause is the inability to set next-hop address for ospf route even though external routes have a 'forward address' field.
It looks like that there are three solutions, (a), Router B talks EBGP with Router C and then redistribute to OSPF (b), Router B talks IBGP with Router A and then redistribute to OSPF, redistribution may not be necessary if you don't care traffic from other routers goes to Router A first, then to B and C. (c), Create a tunnel between Routers A and C so that A sends traffic to tunnel IP, instead router C Personally I prefer (b) because only one EBGP is required to the customer. I just need to figure out the IBGP config on Router A so that it only sends the customer routes instead of the whole table. Thanks, Richard
