Border Gateway Protocol

BGP stands for Border Gateway Protocol.  It is a routing protocol that is used to transmit the information on the internet.  It is used to exchange the information between the gateway in a autonomous network.  BGP deals with routing the information in the big networks like internet, ISPs, universities and enterprise networks.  It is the recent protocol that EGP and it was designed to replace the EGP. 

It is inter autonomous system protocol. BGP uses many routes to achieve the scalability.  It has the mechanism to support the complex routing functions and policies.  BGP is the exterior routing protocol for the internet. BGP4 is an exterior routing protocol and it is used to transmit the information between the autonomous systems. BGP neighbors must reside on the same physical network.

It runs on the TCP port number 179.  It performs the inter domain routing in the TCP/IP based networks.  Like the other routing protocols, it maintains the routing table, transmits the routing updates and metrics.  It uses the single routing metric to determine the best path that is to be assigned to the network.