strange LAN problems

[patrick.peters]

I'm seeing 2 LAN problems I don't understand. If you've got ideas, I'd love to hear them...

#1: I've got a PIX 506 connected to a 2924 switch. I'm seeing late collisions reported on the switch port where the PIX is connected. How do you get late collisions when there's only 2 pieces of equipment connected by a cable? We've replaced both the PIX and the cable without affecting the problem.

#2: I've got a small server connected to that same 2924 switch. There's also a SOHO 91 router connected to the switch (we're routing between 2 different networks at this site and this was a cheap router). The traffic we're passing through this SOHO router is pretty basic SQL database traffic. The error rate on packets output from the SOHO router toward the 2924 switch is nasty: 5% output errors, 14% collisions. We're just talking about a router and switch with a cable between them. SQL traffic is transaction oriented, so I can't imagine that they're both talking at the same time very much, but 14% collisions seems obscene. The 2924 reports similar statistics. If we replace the SOHO router with a cheap little Linksys router and run similar tests, the Linksys stops responding to pings for seconds at a time.

Any ideas?

Thanks

Pat

[smif101 · Accepted solution]

The reason you are getting collisions is that you don't have them set for full duplex. Hard code all the equipment that is having problems to full-duplex instead of half-duplex.

[thiland · Accepted solution]

In most cases, late collisions on a switched ethernet port are caused by duplex mismatches.

Choose 1 option:

1. Hard code both sides of the link to 100Mbps/Full duplex (PIX and switch, router and switch, server and switch)

2. Set both sides of the link to auto-negotiate. This is usually NOT the preferred method between network devices. Typically, you only want auto-negotiation to ports connected to workstations/PCs.

[patrick.peters]

It looks like that fixed it. Thanks for the lead.