[c-nsp] OSPF Dampening

[Tassos Chatzithomaoglou]

And after all this, please post the whole script here so we can all take advantage of it :)

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

Regards,
Tassos

Rodney Dunn wrote on 29/9/2006 5:28 μμ:
> 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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