What is BGP network ?
BGP stands for Border Gateway Protocol, it is core routing protocol of the Internet which contains a colletions of multiple networks and IP tables. It maintains the network IP’s and designates network reachability among autonomous systems (AS). BGP was created to replace the EGP routing protocol system to allow removal of NSFNet Internet backbone network. The internet version IP4 was support of Classless Inter-Domain Routing.
BGP is used by Internet service providers to establish routing between one another, it is one of the most important protocols of the Internet. BGP performs interdomain routing in Transmission-Control Protocol/Internet Protocol (TCP/IP) networks. BGP performs three types of routing: interautonomous system routing, intra-autonomous system routing, and pass-through autonomous system routing.
01. Interautonomous system routing is established between two or more BGP routers at different autonomous systems. BGP neighbors communicating between autonomous systems must reside on the same physical network.
02. Intra-autonomous system routing is established between two or more BGP routers located within the same autonomous system. The BGP protocol can provide both inter- and intra-autonomous system routing services.
03. Pass-through autonomous system routing is established between two or more BGP peer routers that exchange traffic across an autonomous system that does not run BGP. BGP must interact with whatever intra-autonomous system routing protocol is being used to successfully transport BGP traffic through that autonomous system.
BGP devices exchange routing information upon initial data exchange and after incremental updates. BGP routers exchange their entire BGP routing tables. An update message is used to provide routing updates to other BGP systems. Updates are sent using the Transmission-Control Protocol (TCP) to ensure reliable delivery.