Wednesday, February 8, 2012

BFD Session status Changes to Down & Up

While working on DataCom Network (composed of hundreds of NE routers, configured with MPLS, IS-IS, QoS, MPLS-VPN, MPLS-TE, BGP and list goes on and on……..!, I saw this alarm “BFD Session status Changes to down” and “BFD Session status changes to up”. After doing some research, studying and help, I came to know about the root cause and main reason for this alarm.

There can be different reason for alarm to appear:

1. The status of the interface goes down on which the BFD session is established between the two peers.

2. The BFD peer session is deleted or shutdown explicitly.

3. The link is not able to forward packets because of congestion or may be the link status is down.

In my case it was NSA (Non-Service Affecting) and I just need to confirm the status so for that we need to remember few commands which are:


display interface [interface name]


display bfd session all

There are bundle of more commands, if you need any help regarding that please feel free to reach me.

Note: If you are not familiar about BFD? Wait for my next blog on BFD

I Hope this will be informative for you :)