Enterasys Networks Security Router X-PeditionTM - Manual (Page 167)

Overview
XSR User’s Guide 6-19
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-client command.
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.