Border Gateway Protocol Presented BY

Jay Purohit & Rupal Jaiswal 304455065 304442169 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 100A

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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