28-09-2012, 04:10 PM
Border Gateway Protocol
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What is Protocol?
The literal meaning of the English word "Protocol" implies ‘A code of correct conduct’. In the language of Computers this word indicates ‘A standard procedure for regulating data transmission between computers’. Owing to the many ways in which computers can communicate with each other, there are several different protocols like PPP, TCP/IP, SLIP, HTTP, and FTP to name a few.
The Single and Multi Autonomous Systems
The autonomous system (AS) is a collection of routers, computers, and other components within a single administrative domain. When the routing is provided within a single autonomous system, it is known as the Interior Gateway Protocol (IGP). The best known examples of IGP out of the many are Routing Information Protocol (RIP) and Open Shortest Path First (OSPF). But, when the routing information is exchanged between two neighbor gateway hosts, each with its own router in a network of autonomous systems, it becomes the External Gateway Protocol. The most widely used exterior gateway protocol is the Border Gateway Protocol.
Border Gateway Protocol (BGP)
Keeping in pace with changes in the systems connected to the internet, the most efficient paths between systems ,in other words the routing tables need to be updated from time to time. BGP is the protocol that serves this purpose for the global Internet. When BGP fails, portions of the Internet may become obsolete for a period of time ranging from minutes to hours. The increasing popularity of BGP stems from its unique ability to disseminate information by selecting the best route to each destination according to policies specified by network administrators. The routing table in the BGP contains a list of known routers, the addresses they can reach, and a cost metric associated with the path to each router so that the best available route is chosen.