nanog mailing list archives
Re: Analysing traces for performance bottlenecks
From: Sam Stickland <sam_mailinglists () spacething org>
Date: Thu, 17 Jul 2008 16:52:51 +0100
Matt Cable wrote:
Kevin Oberman <oberman <at> es.net> writestcptrace is old and pretty basic, but it can provide a LOT if information. Combined with xplot, the graphs often point to the exact nature of a TCP problem, but you need a really good understanding of TCP to figure anything out.Wireshark also provides tcptrace-like graphs ("Statistics -> TCP Stream Graph -> Time Sequence Graph (tcptrace)"). They're not quite as pretty, but are just as effective at tracking down all sorts of TCP problems, provided, as Kevin said, you have a really good understanding of how TCP behaves
Thanks for all the replies so far. While the TCP graphs are useful they are very difficult to read in Wireshark - they really need to be displayed in xplot, but this requires an X11 setup?
I've found NDT: http://e2epi.internet2.edu/ndt/This uses a java applet hosted on a web100 patched linux server to record network diagnostics from connecting clients. A typical report might look like this:
Web100 reports the Round trip time = 122.15 msec; the Packet size = 1260 Bytes; and
No packet loss was observed. C2S throughput test: Packet queuing detected: 1.09% S2C throughput test: Packet queuing detected: 1.32% This connection is receiver limited 84.33% of the time.Increasing the the client's receive buffer (63.0 KB) will improve performance
This connection is sender limited 1.70% of the time.Increasing the NDT server's send buffer (127.0 KB) will improve performance
This connection is network limited 13.96% of the time. The theoretical network limit is 7869.69 MbpsThe NDT server has a 127.0 KByte buffer which limits the throughput to 16.37 Mbps Your PC/Workstation has a 63.0 KByte buffer which limits the throughput to 4.09 Mbps
The network based flow control limits the throughput to 8.73 Mbps Client Data reports link is 'OC-48', Client Acks report link is 'OC-12' Server Data reports link is 'OC-48', Server Acks report link is 'T3'Something that could provide a similar, automated analysis of a TCP stream capture is what I'm after, although I doubt a standard packet capture will be able to provided as many metric as web100 stack can.
Sam
Current thread:
- Analysing traces for performance bottlenecks Sam Stickland (Jul 15)
- Re: Analysing traces for performance bottlenecks Tim Eberhard (Jul 15)
- Re: Analysing traces for performance bottlenecks Sam Stickland (Jul 15)
- Re: Analysing traces for performance bottlenecks Kevin Oberman (Jul 15)
- Re: Analysing traces for performance bottlenecks Matt Cable (Jul 15)
- Re: Analysing traces for performance bottlenecks Sam Stickland (Jul 17)
- RE: Analysing traces for performance bottlenecks Bulger, Tim (Jul 17)
- RE: Analyzing traces for performance bottlenecks Tim Sanderson (Jul 17)
- Re: Analyzing traces for performance bottlenecks Randy Bush (Jul 17)
- Re: Analysing traces for performance bottlenecks Matt Cable (Jul 15)
- Re: Analysing traces for performance bottlenecks Sean Donelan (Jul 17)
- <Possible follow-ups>
- Re: Analysing traces for performance bottlenecks rcheung (Jul 15)