To establish point-to-point connections between peer ASs, you configure a BGP session on each interface of a point-to-point link. Figure 57 shows an example of a BGP peering session.
Figure 57: BGP Peering Session
In Figure 57, Router A is a gateway router for AS 3, and Router B is a gateway router for AS 10. For traffic internal to either AS, an IGP (OSPF, for instance) is used. To route traffic between peer ASs, a BGP session is used.