nanog mailing list archives
Re: Anyone encountered Cisco ATM PVC large delay bug?
From: "Alexei Roudnev" <alex () relcom EU net>
Date: Sun, 23 Apr 2000 01:39:24 -0700
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" <yuning () cndata com> To: "Alex Rubenstein" <alex () nac net> Cc: "nanog-post" <nanog () merit edu> Sent: Thursday, April 20, 2000 5:06 PM Subject: Re: Anyone encountered Cisco ATM PVC large delay bug?
Hi, ----- Original Message ----- From: Alex Rubenstein <alex () nac net> To: Yu Ning <yuning () cndata com> Cc: nanog-post <nanog () merit edu> 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) -------------------------------------------
Current thread:
- Anyone encountered Cisco ATM PVC large delay bug? Yu Ning (Apr 20)
- Re: Anyone encountered Cisco ATM PVC large delay bug? Alex Rubenstein (Apr 20)
- Re: Anyone encountered Cisco ATM PVC large delay bug? Yu Ning (Apr 20)
- Re: Anyone encountered Cisco ATM PVC large delay bug? Alexei Roudnev (Apr 23)
- Re: Anyone encountered Cisco ATM PVC large delay bug? Yu Ning (Apr 20)
- <Possible follow-ups>
- Re: Anyone encountered Cisco ATM PVC large delay bug? Ron Buchalski (Apr 20)
- Re: Anyone encountered Cisco ATM PVC large delay bug? Alex Rubenstein (Apr 20)