Border Gateway Protocol (BGP) is a standardized exterior gateway protocol used to exchange routing and reachability information among autonomous systems on the Internet. BGP is classified as a path-vector routing protocol, making routing decisions based on paths, network policies, or rule sets configured by network administrators. It enables the exchange of routing information between autonomous systems (ASes) and ensures network stability by quickly adapting to route failures. BGP operates at the application layer of the OSI model and uses TCP port 179 for communication.
BGP can be categorized into two types based on its operation within or between ASes:
Interior Border Gateway Protocol (IBGP): Used for routing within an autonomous system.
Exterior Border Gateway Protocol (EBGP): Used for routing between different autonomous systems.
Key features of BGP include inter-autonomous system configuration, next-hop support, policy implementation, coordination among multiple BGP speakers within an AS, and path information. BGP ensures efficient network performance by making optimal routing decisions based on various attributes like weight, local preference, and AS path. It supports Classless Inter-Domain Routing (CIDR) and interfaces well with security protocols like SSL, VPN, and TLS.