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I just started new job in new networking environment, so the networking done before me is a little difficult to trace.

I got a wall jack port which I have to trace down to which port its connected to in the switch. But, I have five network closets on that same level. Each contains 6 Cisco network switches piled on top of each other.

That port is not DHCP. Because of the bad wiring concept, I don't know how to trace that down. Is there any kind of equipment or software I can use to trace it?

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3 Answers

up vote 10 down vote

You could do this without any equipment pretty easily following these steps.

  1. Do an ipconfig/ifconfig on the workstation to find its IP Address or an ipconfig /all and write down the mac. If you choose to get the mac, skip to step 4.

  2. Ping the workstation from the router.

  3. do a show arp | include X.X.X.X from the router to obtain the PC's mac address. Fill in the PC's IP instead of X.X.X.X

  4. on your core switch, do a show mac address-table dynamic address xx:xx:xx:xx:xx:xx where the x's are the mac of the workstation. The mac will show up on the port connected to the switch where the mac was last seen. If it doesn't show up, ping the workstation from the switch then reissue the command.

  5. Since the port where the mac was last seen is most likely an uplink port to another switch, Do a show cdp neighbors detail on the core switch to identify the IP of the neighboring switch where the mac was last seen.

  6. Connect to the neighboring switch and repeat steps 4 and 5 until you find the physical copper port to which the workstation is actually connected instead of an uplink to another switch.

I gave you this example because it is useful to find the port a PC is connected to even in a remote location. If you actually need to know the wall jack number, once you know the port on the switch you can trace the cable in the closet to the patch panel to identify the wall jack #.

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up vote 6 down vote

You need one of these.

The transmitter end sends a tone down the wire, which you can detect on the other end with the receiver. The receiver does not need to have conductivity to the cable to detect the tone.

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Do keep in mind that many of the tone generators out there won't work well if the end is already terminated into a switch. Just because you don't easily find the end doesn't mean that it isn't terminated there or that the cable's necessarily broken. – Adrian Jan 31 at 0:15
Good ones work from quite a distance away too. – Mark Henderson♦ Jan 31 at 0:39
ive never had that issue so far. – Sirex Jan 31 at 13:24
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up vote 0 down vote

I'd configure the management console so I get a log of link-up/link-down notices, pull out the cable twice (so you can distinguish this from a network card reinitializing during boot) and look for the corresponding event in the log file.

If you synchronize your watch with the management console's clock, you can easily test multiple ports that way by writing down the time at which you unplugged and reconnected the cable.

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