[c-nsp] OSPF question

[Rodney Dunn]

Tony Baade wrote:
> We experienced an issue on our network where we have a link between 2 cisco ME6524s.  There was packet loss across the link, but the interfaces on either side never actually dropped.  The packet loss however was severe enough to cause problems w/ our OSPF (the neighbor session kept dropping up and down) and as a result this caused our iBGP hellos to timeout, causing an outage affecting several routers.
> 
> My question is there some way to dampen a flapping neighbor in OSPF? 

Not natively. I tried to get that in a few years ago but couldn't make 
it happen. If you wanted it bad enough you could code it up with EEM and 
a TCL script to watch for a neighbor flap and passive that interface for 
some time.

Interface event dampening covers the link flap but just for the OSPF 
transport we don't do it.

The enhancement request to track it was:

CSCsi29746    Routing protocol neighbor dampening request


  So if the interface doesn't actually go down, but there is X amount of 
packet loss in Y amount of time (or if the neighbor goes up and down a 
certain number of times) the switch will recognize this issue and stop 
using that link? We are already using IP Event Dampening, which didn't 
kick in because the interfaces never actually went down.
> 
> If there's no way in OSPF to do this, is there support for this in another IGP, or is there any other workaround for this kind of situation?
> 
> Any advice is appreciated, thanks in advance,
> 
> t. baade
> 
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