BGP routers connect with each other through peering, which is the process of establishing a logical connection between two routers. Peering can be done through a physical or virtual connection, and there are different types of peering arrangements available for BGP routers:
1. Internal BGP (iBGP) Peering: This is the peering done between routers within an autonomous system (AS). iBGP ensures that all routers within an AS have the same information about the network, allowing for efficient routing.
1. External BGP (eBGP) Peering: This is the peering done between routers in different ASes. eBGP is used to exchange routing information between different ASes and to identify the best path for traffic to reach its destination.
1. Route Reflectors: Route reflectors are used in larger networks to reduce the number of iBGP connections needed between routers. A route reflector acts as a centralized hub, collecting routing information from all iBGP peers and sending it back to them.
1. BGP Confederations: BGP confederations are used to divide a large AS into smaller sub-ASes. Each confederation is treated as a separate AS and can use iBGP to exchange routing information with other confederations.
