Border Gateway Protocol Presented BY Jay Purohit & Rupal Jaiswal GROUP 9

Overview What is BGP? Autonomous system BGP Peering BGP session BGP session states summary BGP Message Type BGP path attributes BGP problems Project demo

What is BGP?  Border Gateway Protocol (BGP) is a standardized exterior gateway protocol designed to exchange routing and reachability information between autonomous systems (AS) on the Internet.  The protocol is often classified as a path vector protocol  BGP version is 4 and TCP port number that it uses is 179  BGP was created to replace the Exterior Gateway Protocol to allow fully decentralize routing.

Autonomous System  Collection of networks with same policy  Usually under single administrative control AS 100 A

BGP Peering  Peering requires the exchange and updating of router information between the peered ISPs, typically using the Border Gateway Protocol  Bilateral peering and Multilateral peering

BGP session

BGP Session States Summary

BGP Packet-Header Field

BGP Message Types  There are four types of the BGP message each with its own role in setting up, maintaining, or tearing down a BGP peering session They are listed below: 1 OPEN messages 2 UPDATE messages 3 NOTIFICATION messages 4 KEEPALIVE messages

OPEN message

UPDATE message

NOTIFICATION message

KEEPALIVE message BGP systems exchange keepalive messages to determine whether a link or host has failed or is no longer available. Keepalive messages are exchanged often enough so that the hold timer does not expire. These messages consist only of the BGP header.

BGP Path Attribute  BGP uses path attributes to determine the best path to the destination. With BGP path attributes network administrator can manage the traffic flow and determine where the traffic will flow  The four categories of attributes are describe below: 1. Well-Known mandatory(AS_PATH,Origin, Next_Hope) 2. well-known Discretionary(Local-pref) 3. Optional Transitive(Aggregator, Community) 4. Optional Nontransitive(Originator_ID, Cluster list )

BGP Problems  with lots of benefits and importance of BGP in network, it also have same problem on it’s maintenance.  The main problem are listed below: 1. Internal BGP scalability 2. Instability 3. Routing table growth 4. Load-balancing problem 5. Security

Project Demo

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