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Weak network switch port???

L

lakedude

Platinum Member
Is it possible that a port on a network switch could be weak? We had fits trying to troubleshoot connectivity to a couple computers today. The green link lights would come on but the computers would fuss about network connectivity. We hooked up a laptop directly to one of the ports with a short patch cable and the laptop worked just fine. At the far end of the 26 meter cable the same laptop did not work. This seemed to indicate wiring issue so we hooked up a TDR to the cabling but we did not find any issue with the wiring in the building. We also ran a 100 foot long patch cable on the floor to the original host and we had no luck with port in question, however when we moved to a different port on a different network switch all was good.

So the port in question works fine with a laptop on a short cable but the same laptop did not work after 26 meters (per TDR measurement) of cabling in the building however the cabling tests fine and it all works well when hooked up to a different port. The original desktop would not work with the house wiring or the 100 foot patch cable when connected to the questionable port. Seems like the port is weak...
 
I had an el-cheapo LinkSys 10/100 (or maybe it was just 10, way back then), 5-port blue switch, and one of the ports was definitely flaky, or "weak". Had to plug a certain rig into it, other rigs didn't work right on that port.

Yeah, it can happen. Unusual, I would think on corporate-level gear, but possible. Is there any sort of debug feature to test the port?
 
We are a big company and I'm just a local technician with no access to that network other than physical. I have full access to our other network but none on the one in question. I'll make some calls first thing tomorrow... We have plenty of good ports on other switches so the problem is solved good enough for now.
 
The network switch in question is a Cisco Catalyst 3750 v2 Series PoE-48. I don't know how old it is as I don't have much to do with that network.

We did have a storm roll through a few days ago that cause some power issues.
 
Last edited:
sdifox said:
Ports can fail over time, or manufacturing defect. How old is it?
Click to expand...
I've seen individual ports fail even on "decent quality" models. Ports and fans.

Unrelated, there was a port and a patch cable was ... ahem ... yanked sideways. Dead port ever after.
 
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