[j-nsp] MX960 NSR Problem

[Richard A Steenbergen]

On Sun, Jul 12, 2009 at 08:36:12PM +0300, Walaa Abdel razzak wrote:
> Experts
> 
> I have MX960 router with JUNOS 9.4R2 having GRES and NSR enabled. When I
> switch from the master to backup RE, Traffic is not interrupted but the
> protocols appears to reset on the old master but the strange thing is
> that it appears not reset on the new master, do you have reason for
> this? The BGP on the neighbor routers didn't flap, but ISIS, BFD session
> flapped on the neighbors.

That is how NSR is supposed to work. When running NSR, the backup RE is 
pre-synchronized to the state of the active RE, so when you do a 
switchover the BGP session appears to be uninterrupted. At some point 
after the switchover is completed, the new backup RE should sync up in 
the same way, but it won't be instant.

BTW if I were you I'm not sure that I would be running NSR in production
on 9.4R2. I've seen a lot of bugs related to it (and even related to
GRES, ever since around 9.1+ it has been very sketchy for me) which can
cause disruptions or even blackholing within packet forwarding when
"something" happens on the backup RE. LDP sessions resetting whenever 
the backup RE was rebooted was extremely annoying. :)

-- 
Richard A Steenbergen <ras at e-gerbil.net>       http://www.e-gerbil.net/ras
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)