FTOS Configuration Guide for the C-Series - Force10 Networks

Since each BGP routers talking to another router is a session, a BGP network needs to be in “full mesh”.
This is a topology that has every router directly connected to every other router. For example, as seen in
Figure 336, four routers connected in a full mesh have three peers each, six routers have 5 peers each, and
eight routers in full mesh will have seven peers each.
Figure 336 Full Mesh Examples
4 Routers
The number of BGP speakers each BGP peer must maintain increases exponentially. Network
management quickly becomes impossible.
Sessions and Peers
8 Routers
6 Routers
When two routers communicate using the BGP protocol, a BGP session is started. The two end-points of
that session are Peers. A Peer is also called a Neighbor.
462 Border Gateway Protocol (BGP)