Network latency problem

[threedots]

Hi, folks. I hope someone here might have an idea about the following:

I have a 100-plus node switched LAN. All traffic between switches runs at 100Mbps. All network cards on the PCs are 10/100 set to auto-negotiate to 100Mbps. I am experiencing ping times of over 150ms from any PC to the router. This should be as low as 9-10ms. Traffic over the LAN and to Internet web sites is very S-L-O-W! Inbound traffic from anywhere through the cable modem is good, and all servers in the DMZ are responding within acceptable speed ranges. The ISP has tested the cable modem for problems and found none. I have port filtering on the router turned off, but port forwarding engaged for selected ports only. Traffic forwards only to servers and not to PCs. I am running a hardware spam filter and a hardware content filter, both checked by their tech folks as operating OK with little latency. In fact, disconnecting them from the network does not eliminate my network latency problem. I run a mix of Win98SE and WinXP-Pro as client PCs.

My question?: what can be causing this latency problem, and how do I identify the device(s) in the network that is causing it?

threedots

 

[bcastner]

See:

http://support.microsoft.com/?kbid=315237

 

[jimbopalmer]

You do mean that the NICs are all still set to AUTO, right?

I tried to remain child-like, all I acheived was childish.

 

[threedots]

Yes, NICs are all set to auto-negotiate. One other thing, and I should have mentioned this before: all of the port activity lights on the main switch are blinking; ie, I'm getting traffic on all ports whether or not a node is turned on. I have been told this MAY be a sign of a NIC sending out wild packets, but how (if this is indeed the cause, and not something else) do I determine which one? I have an unmanaged switch, and it has been powered down and back up again several times.

 

[salmans]

I would user a sniffer on the main switch, but you must connect to a mirroring port or configure the mirroring port otherwise the sniffer wont pick up anything. After connected to the mirroring port I would run the sniffer for a couple minutes and scan through to see if a single IP address is obviusly over active...Hope this helps in your search for the rogue NIC...

"Do it right the first time, and there won't be a second time!"