OSPF Route summarization

Unanswered Question
Jan 11th, 2008

Hi I have OSPF Route summarization up and running on my ABR's

But for some reason when I do a tracert from other router that is not part of the same area this going by other several ways where the interfaces has other metrics.

So if the summarization is removed this trace go by the way correct.

So in confuse I dont know if summarization set some special metric value for the entire area or something like that.

I hope that you can help me on that.

Thanks an regards

I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
s.arunkumar Fri, 01/11/2008 - 21:57

I think u are talking about inter area summarization..

Summarized routes have normally the least metric of all te specific routes it have for the summary.Then these are advertise to other area as type 3 using distance vector behavior..

May be the trace is taking other part as the router may have more specific route to your destination than ur summarized routes..

pls send more details like ur setup etc..

arun :)

mohammedmahmoud Sat, 01/12/2008 - 03:58


Agree with Arun, we need more details to fully answer the question, a couple of things to consider, may be another ABR is not summarizing, or a problem related to the discard route. As for the metric part, prior to IOS 12.0 the metric of the summary route was derived as the lowest (best) metric of the component paths available (RFC 1583), while after IOS 12.0 it accepts the (worst) metric (RFC 2328) by using the command that was added to control this "no compatible rfc1583".


Mohammed Mahmoud.


This Discussion