BGP

Border Gateway Protocol (BGP) is used to exchange routing information for the Internet and is the protocol used between Internet service providers (ISP). Because it is used to traverse multiple service providers, each of which has its own autonomous network, BGP is considered to be an interautonomous system routing protocol. While an ISP’s network or group of networks falls under a common administration and shares common internal routing policies, the use of BGP allows an ISP to inter-exchange customer and ISP routing, carrying traffic from the customer network to an ISP network, then on to another ISP, repeating this scenario n times until the traffic is delivered to the appropriate customer on n ISP’s network.