H3C S7500E Series Operation Manual page 416

Operation Manual – IPv4 Routing
H3C S7500E Series Ethernet Switches Chapter 5 BGP Configuration
Besides using the well-known community attribute, you can define the extended
community attribute using a community list to help define a routing policy.
V. Route reflector
IBGP peers should be fully meshed to maintain connectivity. If there are n routers in an
AS, the number of IBGP connections is n (n-1)/2. Therefore if there are many IBGP
peers, most network and CPU resources will be consumed.
Using route reflectors can solve the issue. In an AS, a router acts as a route reflector,
and other routers act as clients connecting to the route reflector. The route reflector
forwards (reflects) routing information between clients. BGP connections between
clients need not be established.
The router neither a route reflector nor a client is a non-client, which has to establish
connections to the route reflector and non-clients, as shown below.
Figure 5-13 Network diagram for route reflector
The route reflector and clients form a cluster. In some cases, you can configure more
than one route reflector in a cluster to improve network reliability and prevent the single
point failure, as shown in the following figure. The configured route reflectors must have
the same Cluster_ID to avoid routing loops.
5-15