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Re: Anyone encountered Cisco ATM PVC large delay bug?
I think, the clue is in your accounting - you have 100% used bandwidth when you propose 80%. ATM bandwidth is a pretty twisted thing. If so, some queueries appear and it explain the delays. ----- Original Message ----- From: "Yu Ning" <[email protected]> To: "Alex Rubenstein" <[email protected]> Cc: "nanog-post" <[email protected]> Sent: Thursday, April 20, 2000 5:06 PM Subject: Re: Anyone encountered Cisco ATM PVC large delay bug? > Hi, > > ----- Original Message ----- > From: Alex Rubenstein <[email protected]> > To: Yu Ning <[email protected]> > Cc: nanog-post <[email protected]> > Sent: Friday, April 21, 2000 8:01 AM > Subject: Re: Anyone encountered Cisco ATM PVC large delay bug? > > > > > > > > > > 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 > > cells/sec). > > > > You should check cells/sec on the ATM port you are connected to. > > > Yes. I get the utilization statistic from ATM PVC statistic. > > > > > > > > > > > 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) > > > ------------------------------------------- > > > > > > > >