BGP is a routing protocol used to exchange routing information between different autonomous systems (Ases) and is described in RFC 4271, A BGP 4. An IGP such as OSPF or IS-IS have a main role for exchange of routing information within each AS. BGP is very scalable and stable routing, therefore bgp in most cases is deployed to improve/enhanced the existing network.
BGP can scale to million of routes and multiple copies of the Internet route table. Therefore, BGP is the fundamental routing protocol of the internet and is used by every ISP in the world for ISP interoperability. Right now BGP still growth to support various capabilities such as multiple protocol families. Read More