BGP (Border Gateway Protocol)

BGP allows you to create loop-free interdomain routing between Autonomous Systems (ASes). In practical terms, it enables multihoming a network for better redundancy and can route around bottlenecks without human intervention.

While the average Internet user is not aware of it directly, the Border Gateway Protocol (BGP) is pehaps the most important protocol of the Internet, after TCP/IP.

Any two routers that have formed a TCP connection in order to exchange BGP routing information are called "peers" or "neighbours". Two BGP speaking peers form a TCP connection using TCP (port 179) and exchange messages to open connections and and confirm the parameters.

Peers exchange full-path network routing information (AS numbers) that a route should take in order to reach the destination network. This information is used to construct a loop-free graph of ASes. Further routing policies can be applied to enforce some restrictions on the routing behavior.

We recommend using BGP in private and public IP networks of all sizes for better utilization of resources, better redundancy and better scalability.