BGP stands for Border Gateway Protocol. It is an inter-AS ( Autonomous System Routing Protocol ). BGP is the routing protocol that runs the Internet. BGP is used to interconnect network islands ( ASs ) together. BGP is the only IP routing protocol that runs on TCP instead of IP like the other routing protocols, OSPF, RIP, EIGRP.Also BGP is also known as a path vector protocol as it not only tells you how to get to a network IP prefix, but it shows you an AS path of the reachable network.There are two versions of the BGP protocol. EBGP ( External Border Gateway Protocol ) and IBGP ( Internal Border Gateway Protocol ).