[j-nsp] BGP timer

[Thomas Bellman]

On 2024-04-27 09:44, Lee Starnes via juniper-nsp wrote:

> Having difficulty finding a way to prevent BGP from re-establishing after a
> BFD down detect. I am looking for a way to keep the session from
> re-establishing for a configured amount of time (say 5 minutes) to ensure
> we don't have a flapping session for a. link having issues.

Isn't that what the holddown-interval setting does?  It is limited
to 255 seconds (4 minutes 15 seconds), though, and for BGP it is
only allowed for EBGP sessions, not iBGP sessions.

The documentation also says that you need to set holddown-interval
on *both* ends.  I'm gueesing that the holddown only prevents your
end from initiating the BGP session, but that it will still accept
a connection initiated from the other end.

https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/statement/bfd-liveness-detection-edit-protocols-bgp.html

I haven't used BFD for BGP myself, though, only for static routes
on a couple of links.  But there I do use holddown-interval, and
at least when I set it up several years ago, it seemed to do what
I expected: after the link and the BFD session came up again, it
waited (in my case) 15 seconds before enabling my static route
again.


-- 
Thomas Bellman,  National Supercomputer Centre,  Linköping Univ., Sweden
"We don't understand the software, and sometimes we don't understand
 the hardware, but we can *see* the blinking lights!"

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