No connection to gigabit switch - cabling problem

A simple question to which I hope someone has an answer - I've just wired up a CAT7 cable from my patch panel to the cellar, a maximum length of 25m. Connecting the patch panel port to a gigabit ethernet switch gives no connection at all, even with a 100Mbit device, yet connecting it to a 100Mbit switch works fine.

I've tested the continuity of all the cores and they're fine, and religiously followed the wiring instructions, copying existing cabling that is identical and works perfectly, but the cellar connection doesn't work with the gigabit switch. It seems gigabit ethernet is very sensitive to interference, damaged cabling and so on, but how can I find out what's wrong and fix it?

In the end I can live with 100Mbit but as I'd like to locate my server in the cellar it would be nice to have it connected at full speed.

Thanks in advance.

 

do you have a gigabit nic on your server and a gigabit port on your switch?

 

Well, once again here's the proof that the best way to twist the arm of chance is to ask an internet forum...

Just after making the post above I realised that I had not checked for shorts to ground which, as gigabit ethernet is heavily shielded, is quite likely and lo and behold a badly trimmed wire was touching the shielded case which explained why 100Mbit was fine but gigabit not (100Mbit only uses some cores, gigabit requires them all).

And just to make life even more interesting I've also got a dodgy patch cable that seems to be broken internally. Even simple things can go wrong and they're often the last things to get checked :cool

It's does make life more interesting when problems gang up on you...

Edit: Thanks KingSteve - I wasn't getting any connection to the gigabit switch, which auto senses the lower speeds. Actually this was a good thing as it alerted me to the problem.