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Inter-AS Opt B, speed up convergence to ASBR if primary fails

daniel-nilsson
Level 1
Level 1

Hi
How can i speed up convergence to the secondary ASBR if the promary ASBR fails.
The ASBR acts next-hop to routes outside the AS.

Thanks
/Daniel

4 Replies 4

Akash Agrawal
Cisco Employee
Cisco Employee

Hi Daniel,

If my understanding is correct you have two ASBR and both receiving vpnv4 pefixes from peer-as and advertising to RR. End PE routers preferring ASBR-1 over ASBR-2. Convergence here is related to BGP that when PE installs route from ASBR-2 in routing table.

Now default timer for BGP session is 60, 180 , so it will take 3 minutes for RR to withdraw routes learned from ASBR-1 after outage. You can consider below features to improve BGP convergence

- BGP next-hop address tracking

- BGP PIC feature

Regards,

Akash

Hi

Thanks for your reply 

I have tried all I can think of, next-hop tracking looks like the right thing to do but I can't get it to work. I can't get better than 60sek convergence no matter what I do.

Does Asr920 have support for next-hop tracking in vpnv4? 

Hi,

Feature was introduced in IOS XE Release 2.1, if your ASR920 is running latest code than 2.1 i guess next-hop tracking feature should be supported.

This ASR920 is a RR Client with peering to another AS920 who is RR.

As i understand, the ASR920 can't send add path in address-family vpnv4, neither  it can receive?