Afternoon Packet Loss...can't find the source.

[Yuz]

We have been experiencing afternoon packet loss when pinging two servers (NT 4.0sp6a, Snap Server 4100) in the afternoon. It disappeared when we replaced a bad switch a couple of weeks ago, but has just reappeared. Ports and cables were switched, then the servers were plugged into different switches and the problem persisted. Just as quickly as it appeared, it went away. We use a mix of 3com and Linksys switches and hubs. Most of the switches and hubs are unmanaged. Any ideas to troubleshoot this would be appreciated. Thank you!

 

[DrGreen26]

I would check the driver on the NIC card or replace the nic card in ther server itself. Sometimes NIC's start degrading over time and start having problems. Have you tried sniffing the network at the server level?

Mark C. Greenwood, CNE
m_jgreenwood@yahoo.com

With more than 10 years experience to share.

 

[EntilzaSte]

Try running pathping to your machine and see where it loses the packets....

Steve

 

[Yuz]

Mark, thanks for replying. The server's motherboard with integrated NIC and all drivers have been replaced and are current. I don't have any sniffer tools here, do you have any suggestions?
Thanks!
Steve

 

[Yuz]

Thanks, Steve. I'm not familiar with pathping, but I'll give it a shot. The packet loss has been 0 for quite some time now and makes me think it could have been a fluke or some hardware beginning to fail. Any other ideas or suggestions are welcome. Thank you!
Steve

 

[DrGreen26]

You can download Ethereal for free and use it as a sniffer. JUst make sure you mirror ports if you are connecting to a switch. If you connect to a hub, it should pick up more than you want to see. Setup some filters etc.

If the problem persists during a specific time of the day everyday, just capture the packets during that time frame and what you are going to want to pay attention to are error packets or re-broadcasts, packet loss errors etc.

You may even see something start running on the network during that time that consumes bandiwdth and prevents the server from communicating.

No easy task, but sniffing the network should do the trick.

HTH Mark C. Greenwood, CNE
m_jgreenwood@yahoo.com

With more than 10 years experience to share.