servers behind ACE periodically become unreachable

Unanswered Question
Aug 11th, 2009

I've got an implementation with one ACE module and two DNS servers behind it. Balancing is even but the "show serverfarm detail" command shows a very high failures level (about 1/4 of the total connections).

Moreover - both servers become unreachable from outside from time to time. I graph server performance with MRTG and get gaps in my graph during the time when the servers are unreachable, but "show serverfarm detail" shows non-zero current connection counters.

How could this behaviour be explained?

I have this problem too.
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Gilles Dufour Thu, 08/13/2009 - 03:52

you need a sniffer trace to see exactly what is happening.

If ACE counts failures, it means it didn't see the response from the server.

So, get a sniffer trace in front and back of ACE (tengig interface preferably) and wait for the problem.

Then stop the trace and check if for every request you have a response.



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