Port Speed Negotiation Problem

[spynappels]

Hi All,

Has anyone had issues with a port suddenly not negotiating a speed higher than 10Mbps?

I have a WS-10-250-AC switch in an application where there are 2 x NSM5, powered by the 24v PoE supply. Suddenly one of them only was showing up as 10Mbps. Switch F/W is 1.4.5rc2.

I went through all the normal steps, checking the cables, and everything else and the end result was that it appears the switch port itself is the issue. When the port is powered I get the following log entries:

Code: Select all

Dec 31 19:20:25 UI: Port 3 PoE: changed from 'Off' to '24V'
Dec 31 19:20:42 Port: link state changed to 'up' (10M-F) on port 3
Dec 31 19:20:49 Port: link state changed to 'down' on port 3
Dec 31 19:20:55 Port: link state changed to 'up' (100M-F) on port 3
Dec 31 19:20:56 Port: link state changed to 'down' on port 3
Dec 31 19:21:02 Port: link state changed to 'up' (10M-F) on port 3
Dec 31 19:23:15 UI: Configuration changed by admin (172.30.2.103)
Dec 31 19:23:15 UI: Port 3 PoE: changed from '24V' to 'Off'


Note the power cycle was done by me. The above suggests that the port tries to negotiate to 100Mbps but then drops back to 10Mbps. The same NSM5 with the same cable in another port works fine at 100Mbps.

Are there any diagnostics which can be done on the port to check for hardware issues, or is there any other explanation which can be offered? The switch will be difficult to replace, it is here in the UK but was sourced from North America originally, and an RMA for hardware issues would be difficult to arrange, so if there are other options, I'd like to explore them first.

Thanks for any insights you may have.
Stefan

[sirhc]

Well I would upgrade to the latest firmware even though that is not the cause of "this" issue.

I would turn the POE off on the port in question.

I would inspect the port in the switch for dirt or corrosion.

Use a que tip with 99% Alcohol and clean any corrosion off the pins then use a can of air to blow it out and insure the alcohol evaporated.

Now plug your Laptop into the port in question and see if you get a good solid 1G connection.

[spynappels]

Thanks Chris, will get the guys onsite to try that.

Will also need to have a look at the 1.4.6 F/W to check it out, thanks for the headsup.