[c-nsp] OSPF Dampening

[Rodney Dunn]

On Fri, Sep 29, 2006 at 05:53:32PM +0300, Tassos Chatzithomaoglou wrote:
> And after all this, please post the whole script here so we can all take advantage of it :)
>

Stay tuned.


 
> Or maybe even better, try to persuade Cisco to write that script for you (and all of us) ;)
>

Don't expect that. If you want to leverage the infrastructure start
learning TCL.

There will be some we write and include natively in the images but
that number will be very small and limited.

> Regards,
> Tassos
> 
> Rodney Dunn wrote on 29/9/2006 5:28 ??:
> > Oh I'm going to be saying this a lot. :)
> > 
> > 
> > Look at EEM and write yourself a TCL policy that would monitor for
> > flap rate of an OSPF message in the syslog and block that
> > peer. 
> > 
> > ie: put an acl on the interface that blocks ospf packets coming
> > in from it.
> > 
> > Then start a script that pings the neighbor at a rate/time that you
> > feel determines the neighbor is back stable and then have the script
> > remove the ACL and let the neighbor come back up.
> > 
> > And you can have the EEM policy email you all along the way telling
> > you what it's doing. :)
> > 
> > 
> > Rodney
> > 
> > 
> > On Fri, Sep 29, 2006 at 09:02:15AM -0500, Jeremiah Millay wrote:
> >> In BGP there is a mechanism to dampen routes from a peer that is 
> >> flapping. Does anything similar to this exist for OSPF on a Cisco router?
> >> The closest thing I can find is this (IP Event Dampening):
> >>
> >> http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_feature_guide09186a0080110bc8.html
> >>
> >> ...but it won't work for my setup because my interfaces don't flap, only 
> >> the OSPF adjacency is flapping.
> >>
> >> Here is a crude diagram of my setup:
> >>
> >> (a)------(b)
> >>  \          /
> >>   \        /
> >>     (c)
> >>
> >> -Router A's primary path to router C is through B. This connection is 
> >> through a point-to-point wireless connection fed to the routers via ethernet
> >> - When the conenction from router A to B goes down, the link from A to C 
> >> is to become active.
> >>
> >> I'm having problems with the radios failing between router A and B. 
> >> Because the ethernet link never goes down and it still receives hellos 
> >> sporadically the link from A to C never becomes active. On router A I 
> >> get log output similar to the following (and it repeats over and over):
> >>
> >> *Sep 28 17:05:55: %OSPF-5-ADJCHG: Process 1, Nbr X.X.X.X on 
> >> FastEthernet0/0 from LOADING to FULL, Loading Done
> >> *Sep 28 17:06:56: %OSPF-5-ADJCHG: Process 1, Nbr X.X.X.X on 
> >> FastEthernet0/0 from FULL to DOWN, Neighbor Down: Dead timer expired
> >> *Sep 28 17:07:24: %OSPF-5-ADJCHG: Process 1, Nbr X.X.X.X on 
> >> FastEthernet0/0 from LOADING to FULL, Loading Done
> >> *Sep 28 17:09:03: %OSPF-5-ADJCHG: Process 1, Nbr X.X.X.X on 
> >> FastEthernet0/0 from FULL to DOWN, Neighbor Down: Dead timer expired
> >> *Sep 28 17:09:20: %OSPF-5-ADJCHG: Process 1, Nbr X.X.X.X on 
> >> FastEthernet0/0 from LOADING to FULL, Loading Done
> >> *Sep 28 17:10:44: %OSPF-5-ADJCHG: Process 1, Nbr X.X.X.X on 
> >> FastEthernet0/0 from FULL to DOWN, Neighbor Down: Dead timer expired
> >>
> >> I would like to be able to dampen the routes from a neighbor when the 
> >> interface itself does not flap but the adjacency flaps. Is there any way 
> >> to do this or am I outta luck?
> >> Thanks in advance,
> >> Jeremiah
> >>
> >>
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