Border Gateway Protocol
It is a protocol needed to advertise the set of networks that can be achieved within an autonomous machine. BGP activates this information to be shared with the autonomous machine. This is newer than Exterior Gateway Protocol. Border Gateway Protocol is the protocol which creates basic routing decisions on the Internet. It performs a table of IP networks or 'prefixes' which define network reach-ability among autonomous systems. It is defined as a path vector protocol. BGP does not need traditional Interior Gateway Protocol metrics, but creates routing decisions based on way, network policies and/or principal-sets. For that reason, it is known as reach-ability protocol not the routing protocol.