Enterasys Networks X-PeditionTM Route Reflectors, Route Reflector Applied to Minimize Ibgp Mesh

Overview

Route Reflectors

Route reflectors are an alternative to the requirement of a fully meshed network within an AS, as illustrated in Figure 6-11. This approach allows a BGP speaker (known as a route reflector) to advertise IBGP learned routes to certain IBGP peers. This is a variation from the standard IBGP behavior of not re-advertising IBGP-learned routes to other IBGP speakers. But, if this rule is relaxed, the number of IBGP sessions can be greatly reduced.

This functionality is configured with the neighbor route-reflector-clientcommand.

Figure 6-11 Route Reflector Applied to Minimize IBGP Mesh

As there are route reflector- compliant BGP speakers, some BGP speakers may not comply with route reflector behavior. They can be either client or non-client group members. This situation does not prohibit configuring reflectors, though. At first, you can configure one cluster with a route reflector and some clients. You can consider all other IBGP speakers non-client peers to the route reflector and add more clusters.

More than one route reflector can be associated with an AS. As such, a route reflector treats other reflectors similar to other IBGP speakers and it can be configured to include other reflectors in a client or non-client group. A rudimentary scenario would divide the backbone into multiple clusters and each route reflector configured with other route reflectors as non-client peers (fully meshing all reflectors). Clustered clients would be set up to keep IBGP sessions going with only the reflector within.

XSR User’s Guide 6-19