Summary

Border Gateway Protocol 4 (BGP-4) is a dynamic routing protocol that exchanges network reachability information with other BGP peers. BGP is most commonly used in service provider networks and in large enterprise networks, and it is widely deployed to manage IP traffic. The power of BGP policy control through its attributes (LOCAL_PREF, AS_PATH, MULTI_EXIT_DISC [MED], Origin, NEXT_HOP and so on) provides network operators strong control over IP traffic flow.

In addition to IPv4, BGP has been extended to support multicast and VPN-IPv4.

Cisco IOS Software offers rich support of BGP, and this chapter should be a starting point in understanding Cisco IOS Software implementation. Readers are encouraged to read the Cisco IOS Software documentation for a detailed explanation of the configurations discussed in this chapter.