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BGP Message Types & FSM

In this tutorial we will discuss about different message types of BGP, BGP Peer Connection, BGP Finite State Machine. Before establishing BGP Peer Connection, two neighbor must perform TCP Three-Way-Handshake and open a connection to Port number 179. BGP is a Transport Layer Protocol, hence TCP provides fragmentation, acknowledgement, sequencing functions necessary for reliable connection. BGP Peer must be statically configured and a route must present in the routing table. All the BGP Messages are unicast over TCP Connection. BGP Uses five basic message. BGP Messages All BGP Messages have a common header and encapsulated into a TCP Fragment. Header consists of Marker, Length and Type of the BGP Messages. A Keepalive message is nothing but a BGP Header. Open Message consists of version number of bgp, autonomous system number of the originating router, hold time, bgp identifier and optional parameters for capabilities negotiation. A Update Message consists of withdrawn […]

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