The Border GatewayProtocol (BGP) is an Exterior Routing Protocol (ERP) that transmits routing information between autonomous systems (AS). The Border Gateway Protocol (BGP) works with interdomain routing in which the routing takes place between the autonomous systems. The routers inform each other about the available connection paths. The strength of the BGP protocol lies in its ability to combine various optional routing paths into a single routing table
theExterior Gateway Protocol (EGP), which is superseded by the BGP protocol, the Border Gateway
Protocol isa path vector protocol for routing between autonomous systems (ASs). BGP supports a metric and can make intelligent routing decisions. It can interoperate with Open Shortest Path First (OSPF) as an internal routing protocol. In particular, it supports Classless Interdomain Routing
(CIDR) route aggregation.BGP information contains all the data about the complete path between autonomous systems. Based on this information, the protocol creates a graph that represents the interconnection of the different Autonomous Systems and eliminates looping of the routing. The routing update, where a BGP router is in communication with other BGP systems, is transmitted using TCP protocol. The metric used by the BGP protocol is based on information that the network administrator assigns to the routers when they are configured, as well as the physical and transmission parameters. Since each BGP router has route information from other BGP routers, especially the neighboring BGP routers, each BGP router builds a database for routes
to all reachable Autonomous SystemsThe BGP protocol is described
inRFCs 1163 and 1771. In 1991, RFC 1269 published the Border Gateway Protocol (version 3) Management Information Base
(MIB). Version 4, which supports CIDR, is currently in use. It is described in RFC 4271 and is suitable forGigabit Ethernet
. The BGB protocol also exists as Interior-BGP (IBGP) and Exterior-BGP (EBGP), which performs routing between two autonomous systems (AS).