[c-nsp] OSPF Dampening

Jeremiah Millay jeremiah at rockriver.net
Fri Sep 29 10:02:15 EDT 2006


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




More information about the cisco-nsp mailing list