5406zl: illogical connection issue

[josh bernardini]

I'm a bit stumped by this one. I have home run cabling from a new classroom to a rack holding a 2810 and a 5406zl. If i plug my windows vista laptop (broadcom 570x NIC) into one of the classroom ports patched through to the 5406, I get port flapping on my laptop NIC, with no indication of connectivity on the 5406 port. If I move that patch cable to the 2810, it lights right up, and I get a gb connection on the laptop.

If I plug my laptop directly into the same port (true for all tested ports) on the 5406, it lights right up.

If I plug in any of three other clients tested (Mac, XP, Vista) from the classroom, patched through to the 5406, it lights right up.

So it is only with the combination of my laptop connected through the home run cabling into the 5406 - on every cable run and port tested so far - that I see an issue.

The cabling works, as demonstrated by connections from other clients or to other switches.

The switch works as demonstrated by connections from other clients or directly from my laptop.

My laptop NIC works as demonstrated by connections to other switches, or directly to the 5406.

But put the three together and they don't work! Can anyone explain it? Suggest a solution? I think there's a hint in the laptop NIC flapping. It's sensing a connection that the switch doesn't seem to (no LED or MAC address registered on port) ... ?

Thanks in advance for any advice.
jb

[Casey Morford]

I'm having a little trouble following your different tests, but what I do know is gigabit needs all 4 pairs in your ethernet run to be connected correctly from end to end.

I'm not sure if your Mac/XP/Vista clients in the classroom are Gigabit, but it is possible that if they are 10/100 that they could link up just fine even if a pair in your cable run is flaky. Anyway, just a thought from some of my experiences, good luck!

[josh bernardini]

That was my best guess too, but the home run cable carries a Gb connection to the 2810 from my laptop, the Mac and XP clients; and to the 5406 from the Mac and XP clients but not my laptop.

So as much as I'd like to be able to blame the wiring contractor, I don't see how I could!? 500Mbps throughput confirmed with Qcheck, and the contractors tests all check out.

[Casey Morford]

Have you tried setting the port speed-duplex to something other than auto? like 1000-full? If that works with your laptop, then perhaps the switch and your laptop are having trouble negotiating the speed.