Do BGP routers establish peer relationships using UDP?

BGP (Border Gateway Protocol) routers establish peer relationships using TCP, not UDP. This is because BGP requires a reliable transport mechanism to ensure that routing information is exchanged accurately and in the correct order. TCP, which is a connection-oriented protocol, provides this reliability by establishing a connection between BGP peers before any data is exchanged, ensuring that all packets arrive at their destination without loss, duplication, or out-of-order issues.

UDP, on the other hand, is a connectionless protocol that does not guarantee delivery, which would be inadequate for the needs of BGP. Using UDP could lead to issues where important routing information may be lost or corrupted, making it unsuitable for the stable operation of routing protocols.

In summary, BGP’s reliance on TCP illustrates the importance of a reliable transport layer in network communication, particularly for protocols that manage critical functions like routing decisions across the internet.