[c-nsp] Fast Reroute and Link Flapping

[alaerte.vidali at nsn.com]

Hi Oli,

Could you comment the 10-sec link-up debounce of POS?

It is not the behavior on the links I handled last time.

Tks,
Alaerte 

-----Original Message-----
From: ext Oliver Boehmer (oboehmer) [mailto:oboehmer at cisco.com] 
Sent: Thursday, April 19, 2007 12:23 AM
To: Vidali Alaerte (NSN BR/Rio de Janeiro); cisco-nsp at puck.nether.net
Subject: RE: [c-nsp] Fast Reroute and Link Flapping

alaerte.vidali at nsn.com <> wrote on Thursday, April 19, 2007 1:30 AM:

>  Hi,
> 
> Do you have reference that discuss fast reroute and link flapping?

not aware of one, but how fast a link flap would you be interested in,
and what is your TE config? Once the protected link has failed and the
LSPs are rerouted via the backup tunnel, the headend(s) will try to
re-optimize the tunnel around the link. If the failed link comes back,
by default the tunnel headends will not trigger a reoptimization (can be
enabled, however), so existing tunnels will not immediately cross the
link in question.
Any LSA/LSP throttling will also apply, so a rapidly flapping link will
trigger the backoff and the IGP throttles down.
I'd always enable IP dampening to prevent rapidly flapping links from
causing any churn on your network. POS already as a 10-sec link-up
debounce timer, but enableing dampening on it doesn't hurt.

	oli