Communication and network protocols. Computer networking.

1. BGP
B O R D E R G AT E W AY P R O T O C O L
P R E S E N T E D TO : P R E S E N T E D BY :
M R S . V I D H U B A G G A N A N I S H A PAT H A N I A
( A S S O C I AT E P R O F E S S O R ) M E 1 7 1 0 9 8 1 0 5 2

2. OUTLINE :
• Introduction
• Different terms
• Message types
• BGP states

3. BGP
An exterior gateway protocol, exchange information between
Autonomous systems. (BGPv4)
Introduction
AS: network that operates
separately from other networks
and usually operates within a
single administrative domain
Routing
Decisions • Path
• Network policies
• Rule sets
*set by network Administrator
BGP
Peers
Neighbors of the router
Connections through TCP port 179

4. 1 Open
• Include set of parameters
• Need to be agreed by
peers
2 Update
• Contain NLRI (network
layer Reachability
information
• Actual route updates
3 Keep-alive
• If no update keep the
session running
• After “no peer” remove all
roots heard
BGP Message types
4 Notification
• Sent when: Error messages,
corrupt update
• Or in case of emergency
route shut

5. BGP States
1. IDLE
2. Connect
3. Active
4. Open
sent
5. Open
Confirm
6. Establish
ed
• Listen/starts TCP connection with BGP peers
• Fails- stay at Idle, else move to connect state
• TCP 3-way handshake
• If fails- active state, if timer expire stay
same
• If success- open-sent state, else- Idle state
• Try another handshake or listen to TCP
connection
• If success- open-sent state,
• if timer expire- connect state, else- Idle
state• Wait for open messages and check for
errors
• If error- Idle state with notification message
• If ok- keep alive message sent
• Wait for keep alive message and move to
established state
• If receive notification message- Idle state
• BGP routers send update packets to exchange routing
information
• If receive notification message- Idle state

6. THANK YOU…