1. Border Gateway Protocol
(BGP)

2. TEAM
 Team Members
Group 9
 Yogeshwar P.Kulkarni
 Parth Varmora
 Salman Sikinder
 Manish Parmar
 Anand Patel

3. INTRODUCTION
 BGP protocol for exchanging routing
information between gateway hosts (each with
its own router) in a network of autonomous
systems.
 he routing table contains a list of known
routers, the addresses they can reach, and a
cost metric associated with the path

4. Autonomous System (AS)
Fig:
 Collection of networks with same policy
 Single routing protocol
 Usually under single administrative control
 IGP to provide internal connectivity
AS 100

5. Overview-BGP

6.  Hosts using BGP communicate using uses TCP.
 BGP communicates with autonomous (local) networks using Internal
BGP (IBGP).
 Routers inside the autonomous network thus maintain two routing
tables: one for the interior gateway protocol and one for IBGP
 It uses path vector protocol
 Can have multiple paths for a given prefix
 Picks the best path and installs in the IP forwarding table

7. BGP state machine

8. Types Of BGP Session
 Internal BGP
 External BGP

9. BGP Routing Process

10. BGP Messages
 Open
 Announces AS ID
 Determines hold timer – interval between keep_alive or
update messages, zero interval implies no keep_alive
 Update
 Keep_alive
 Sent periodically (but before hold timer expires) to peers to
ensure connectivity.
 Sent in place of an UPDATE message
 Route-Referesh
 Notification
 Used for error notification
 TCP connection is closed immediately after notification

11. Version:
 The current version of BGP is BGP
version 4, based on RFC4271
 Previous Version: RFC 1771