Hi all, I'm having some trouble wrapping my head around how VRF RDs and RTs are being handled by the router.
First, some things I know (I think...): - A VRF holds a set of routes, and is a copy of the standard routing table - A RD is set per-vrf and its sole purpose is to create a way for BGP to distinguish between identical prefixes from different VRFs - Routers do not use the RD to make import/export decisions into VRFs - An export RT on a VRF means that if the router advertises a route from that VRF into BGP, it will attach the extended community specified in the export statement - An import RT on a VRF means that if the router receives a prefix from BGP that has the specified community set, it will import it into the VRF where the import statement is configured It came as a revalation to me that the RD doesn't have ANYTHING to do with importing/exporting routes -- so much of the docs I've read seem to imply that it does! Okay, so here's what I don't get. Say we're doing a central services MPLS VPN. Two customers, one central services VPN so there are three VRFs in play. Assuming only one PE per customer/server site to simplify a bit. Exports: Customer 1's routes are exported from their PE into MP-BGP with a RT of 1 (not valid, but this is an example). Customer 2's routes are exported from their PE into MP-BGP with a RT of 2. Central services's routes are exported from their PE with a RT of 3. Imports: Customer 1 imports routes with a RT of 3 to receive central services routes. Customer 2 imports routes with a RT of 3 to receive central services routes. Central services imports routes with an RT of 1 and 2 to receive Customer 1 and 2's routes. Based on the reading I've done, at this point Customer 1 and Customer 2 should be able to communicate with Central Services but not with each other. But that doesn't really make sense to me! Wouldn't central services *import* routes from Customer 1 with an RT of 1 and then *export* those same routes with an RT of 2? Wouldn't that mean that both Customer 1 and Customer 2 are receiving each other's routes, with the Central Services PE acting as a route bridge? Any lead on what I might be missing, as well as confirmation of what I think I know, would be very much appreciated. Thanks, experts! Keller Giacomarro [email protected] _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com http://onlinestudylist.com/mailman/listinfo/ccie_rs
