Saturday 2 May 2020

BGP CHAPTER 10- BGP NEIGHBOR STATES


In this blog we will be focusing on BGP Chapter 10 - BGP Neighbor States a.k.a FSM i.e Finite State Machine.

I would recommend to go through previous chapter BGP Messages to get better understanding of this chapter .

So lets  Start  by know few points regarding BGP Neighborship 

  • BGP uses TCP PORT 179 to form Neighbor Adjacency.
  • In BGP Manually configuration of neighbor is required since BGP does not use Mulitcast or Broadcast to discover Neighbors.
Idle :

The BGP process is either administratively down or awaiting the next retry attempt.

Connect :

The BGP process is waiting for the TCP connection to be completed.

Active :

The TCP connection failed , Connect - Retry timer running , listening for incoming
TCP connection.

Opensent :

The TCP connection exists and a BGP Open message has been sent
to the peer , but the matching Open message has not yet been received from the
other router.

Openconfirm :

An Open message has been both sent to and received from the other router.

Established :

All neighbor parameters match , the neighbor relationship works and the
peers can now exchange.

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