-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Almost sounds like there is a loop somwehere. The MDI MDIX does not worry me all that much.
How many machines and switches/routers are we talking about? I have also tracked down some weird TCP window scaling scaling issues this year. If the problem is limited to certain hosts (Vista or recent linux kernels), then perhaps: sysctl -w net.ipv4.tcp_window_scaling=0 I would also leave mtr running for an hour or two and see what it records. Cheers, On Thu, 6 Sep 2007, Martin Glazer wrote: > Date: Thu, 06 Sep 2007 04:01:07 -0600 > From: Martin Glazer <[EMAIL PROTECTED]> > Reply-To: CLUG General <[email protected]> > To: CLUG General <[email protected]> > Subject: Re: [clug-talk] OT: Network Tester > > Shawn and Gustin, thanks for the suggestions - I will take a look at > netem. I did look use iperf and a few other tools like nuttcp and > thrulay but couldn't reproduce the problem or get the network to fail. > > The issue I am trying to troubleshoot is intermittent and random (the > best kind!). I have so far managed to use tcpdump to capture the > problem, but htis doesn't tell me what is causing it. I need ot get to > the layers further down the model - Frame and Physical. > > I certainly cannot afford to buy one of those handy dandy network > monitoring and testing tools, but I would be prepared to rent one or pay > someone to test for me. > > On a related note - I didn't install the physical cabling and noticed on > the managed switch that some of the ports are set to MDI and some others > to MDIX - does anyone think that this could be an issue - I wouldn't > think so as the switch is sensing the configuration, but you never know... > > Thanks > > Martin > > Gustin Johnson wrote: >> -----BEGIN PGP SIGNED MESSAGE----- >> Hash: SHA1 >> >> Since you have a linux network I would look into iperf, which should be >> packaged in most major distros. mtr can be handy for locating problem >> links. >> >> On a related, slightly OT note, you can simulate various kinds of >> problems with these examples: >> >> http://linux-net.osdl.org/index.php/Netem >> >> Hth, >> >> Martin Glazer wrote: >>> Hi, >>> >>> I'm experiencing some network issues and I'm trying to track them down >>> - have run tcpdump and been checking logs, but to no avail. I suspect >>> that there could be something now physically wrong with the network. The >>> issues are intermittent. >>> >>> Does anyone know how I can go about testing the lower levels - what >>> equipment do I need, can I rent it, is there a company in Calgary that >>> does this? >>> >>> I know this is not directly related to Linux, we are running on a Linux >>> network. >>> >>> Thanks >>> >>> Martin >>> >>> _______________________________________________ >>> clug-talk mailing list >>> [email protected] >>> http://clug.ca/mailman/listinfo/clug-talk_clug.ca >>> Mailing List Guidelines (http://clug.ca/ml_guidelines.php) >>> **Please remove these lines when replying >> -----BEGIN PGP SIGNATURE----- >> Version: GnuPG v1.4.6 (GNU/Linux) >> Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org >> >> iD8DBQFG305pwRXgH3rKGfMRAqIUAJsErnHBV3E1+A2vA+7Pom1ji06L4QCdFF9v >> LM63LSWk/GSp7GjOJkdFDzQ= >> =yD/L >> -----END PGP SIGNATURE----- >> >> _______________________________________________ >> clug-talk mailing list >> [email protected] >> http://clug.ca/mailman/listinfo/clug-talk_clug.ca >> Mailing List Guidelines (http://clug.ca/ml_guidelines.php) >> **Please remove these lines when replying > > _______________________________________________ > clug-talk mailing list > [email protected] > http://clug.ca/mailman/listinfo/clug-talk_clug.ca > Mailing List Guidelines (http://clug.ca/ml_guidelines.php) > **Please remove these lines when replying > -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) iD8DBQFG3920wRXgH3rKGfMRAsUPAJ0TaRHdOpbWu4ngg8rdPVgzF1X67gCgsSii WJh5z7kV2LR1AfXl4qaP1DM= =JqlY -----END PGP SIGNATURE----- _______________________________________________ clug-talk mailing list [email protected] http://clug.ca/mailman/listinfo/clug-talk_clug.ca Mailing List Guidelines (http://clug.ca/ml_guidelines.php) **Please remove these lines when replying
