In normal situations, a full internal Border Gateway Protocol (iBGP) mesh is required within an Autonomous System (AS). To reduce the number of iBGP peers within an AS, use Route Reflectors (RRs).
To resolve this problem, issue the neighbor route-reflector-client command.
The router with the neighbor route-reflector-client command is the RR. The neighbors pointed at are clients of that RR. The combination of the RR and its clients is called a cluster.
For more information on RRs, refer to the Route Reflectors section of BGP Case Studies.