nanog mailing list archives
RE: Cisco PPP DS-3 limitations - 42.9Mbpbs?
From: "Daniel Golding" <dgolding () sockeye com>
Date: Wed, 20 Feb 2002 11:30:36 -0500
If you are just doing testing, then sending a stream of UDP echos across, using something like a Digital Lightwave is the easiest way of testing, provided your target system will take the traffic (this is a good way to crash most windows boxes, for example). PPP and HDLC both have very little in the way of overhead. The same can be said for c-bit framing. You should be getting something like 96% efficiency, which gets you to the 42.9mb/sec number. PPP has something like 7 bytes of overhead per frame. Various forms of DS3 framing are discussed here: http://www.dl.com/ResearchCenter/Training/t3/t3fund.pdf. ATM, for comparison, will usually max at around 36mb/sec for a DS3. YMMV of course, and in actual operation, due to peaks and 5 minute sampling, you will see lower bit rates. - Daniel Golding
-----Original Message----- From: owner-nanog () merit edu [mailto:owner-nanog () merit edu]On Behalf Of Stephen J. Wilcox Sent: Wednesday, February 20, 2002 11:09 AM To: Randy Bush Cc: nanog () merit edu Subject: Re: Cisco PPP DS-3 limitations - 42.9Mbpbs? Hmm, reasonable explanation.. presumably this can be improved (a little) with increased interface buffers.. ? and possibly non fifo queuing eg custom queuing in favour of TCP rathen than UDP/ICMP etc which wont have the backoffs Cheers Steve On Wed, 20 Feb 2002, Randy Bush wrote:we run HDLC on DS3 and we max at about 40.something tooif you're using five min (or three min) samples, and you're seeing 70%, peaks are likely much higher and some users' packets are being dropped. by 80%, enough packets are being dropped that users are likely to see the effects of exponential backoff. things do not improve above 80%. randy-- Stephen J. Wilcox IP Services Manager, Opal Telecom http://www.opaltelecom.co.uk/ Tel: 0161 222 2000 Fax: 0161 222 2008
Current thread:
- Cisco PPP DS-3 limitations - 42.9Mbpbs? Ehud Gavron (Feb 20)
- Re: Cisco PPP DS-3 limitations - 42.9Mbpbs? Stephen J. Wilcox (Feb 20)
- Re: Cisco PPP DS-3 limitations - 42.9Mbpbs? Randy Bush (Feb 20)
- Re: Cisco PPP DS-3 limitations - 42.9Mbpbs? Stephen J. Wilcox (Feb 20)
- RE: Cisco PPP DS-3 limitations - 42.9Mbpbs? Daniel Golding (Feb 20)
- Re: Cisco PPP DS-3 limitations - 42.9Mbpbs? Randy Bush (Feb 20)
- Re: Cisco PPP DS-3 limitations - 42.9Mbpbs? Stephen J. Wilcox (Feb 20)
- Re: Cisco PPP DS-3 limitations - 42.9Mbpbs?y Neil J. McRae (Feb 20)
- Re: Cisco PPP DS-3 limitations - 42.9Mbpbs? Randy Bush (Feb 20)
- Re: Cisco PPP DS-3 limitations - 42.9Mbpbs? Greg Maxwell (Feb 20)
- Re: Cisco PPP DS-3 limitations - 42.9Mbpbs? Randy Bush (Feb 20)
- Re: Cisco PPP DS-3 limitations - 42.9Mbpbs? Randy Bush (Feb 20)
- Re: Cisco PPP DS-3 limitations - 42.9Mbpbs? Stephen J. Wilcox (Feb 20)
- Re: Cisco PPP DS-3 limitations - 42.9Mbpbs? Alex Rubenstein (Feb 20)
- Re: Cisco PPP DS-3 limitations - 42.9Mbpbs? Jon Mansey (Feb 20)
- Re: Cisco PPP DS-3 limitations - 42.9Mbpbs? Iljitsch van Beijnum (Feb 20)
- RE: Cisco PPP DS-3 limitations - 42.9Mbpbs? Steve Naslund (Feb 20)