North American Network Operators Group

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Re: Anyone encountered Cisco ATM PVC large delay bug?

  • From: Alex Rubenstein
  • Date: Thu Apr 20 20:02:32 2000

Are you accounting for ATM overhead? Remember, the sho in bits/sec do NOT
count overhead (another words, they are looking at true bits/sec, not

You should check cells/sec on the ATM port you are connected to.

> In more detail, our situation is: if we get a high bandwidth PVC,
> say 51M(or 80M), and if the bandwidth utilization reaches 80%
> percent, the ATM link will encounter a 1500~2000 ms delay - just
> point to point ping across the link. We have found this situation 
> is associated with "sar txpool" setting in Cisco GSR, and a manipulation
> of the "sar txpool" together with bandwidth increasing has solved
> the problem now.
> But I still wonder if any of you ever encounter this situation(bug),
> and how did you overcome it? If you are still puzzled by this bug,
> I'd like share our temp solution with you.
> regards,
> Yu Ning
> -------------------------------------------
> (Mr.) Yu Ning 
> ChinaNet Backbone Operation
> Networking Dep.,Datacom Bureau
> China Telecom.,Beijing(100088),P.R.C
> +86-10-66418121/66418122/66418123(fax)
> -------------------------------------------