We have a a multigiabit core network across 6500s. We have numerous distribution routers that are each connected to two core routers at physically diverse locations. Each DR router connects via a single connection to many access-layer routers. All routing is done via a single EIGRP AS.
The DR routers are learning, via EIGRP, all routes for the enterprise network via both core routers. The DRs are also propagating all routes back out to the both core routers. This creates many additional EIGRP topology table entries for for alternate paths from a core router to a DR router back to the 2nd core router. My core is very redundant and I do not want core traffic to consider bypassing the core and going through a DR to get to another core router. Also, in an error / link flapping situation etc, I am concerned that all of the extra possible paths will cause EIGRP excessive overhead and possible failure to properly recover.
Unfortunately the addressing scheme implemented here over many years, will not permit summarization.
I would love to tag the routes being advertised from the core to the DR routers and then filter any tagged routes from being readvertised back out, from the DR, to the core via it's redundant link. But EIGRP does not support route-maps for distribute lists unless we are redistributing into another routing protocol.
Is there a way to generically filter my core learned routes and still advertise all of my access-layer routes. If EIGRP supported EIGRP to EIGRP route maps / tagging, I could create two generic route-maps (one to tag and one to filter) that could be applied to all DR routers and never be bothered with again. Instead, the only way I can see to do it now is to customize very specific distribute-list ACLs for every DR. This would require modifying these ACLs each time we added or deleted a subnet at any access-layer router. Every DR would have a complex, customized ACL. This is painful and unacceptable. Does anyone have any ideas of a better way to do this? Thanks.
