Finding out what devices are attached to a Switch

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Apr 13th, 2007
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I am working on a Rack Clean up project. I can not remove any wire until I know 100% what device is attached to my switches. I am dealing with Cisco 2950s and 3750s. I can not trace the wires because I am not allowed to go under the Data centers floors. Is there a command or program out there that I can run that will let me know what the other devices Mac address and or IP address are. I am using what ever information I can and I have a few IP addresses but Im not 100% that the device that is answering is the next hop over.

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pciaccio Fri, 04/13/2007 - 09:49
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Some basic commands to use are:

Show ip int brief : to see what interfaces are up

Show mac-address-table : to see what mac addresses are off the interfaces.

Show cdp neighbor : to see if their are any other Cisco network devices attached to any interfaces

Try pinging a broadcast ping within the subnet to see what devices answer. Then you can track each IP down and associate them to a MAC address from the Show Mac-address-table command.

These commands should help you out....Good Luck...

srue Fri, 04/13/2007 - 10:17
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i usually combine the show mac-address-table and show arp commands to find out what's connected where. Once I get the mac associated w/ a port, i can look at the arp table to see what IP is associated with the mac. Then use DNS (hopefully) to see what host is associated w/ the ip.

Her is the one that I have been using. It is great...

SwitchInspector is an easy to use application to design, validate or audit your Local Area Network. With SwitchInspector you can obtain detailed information about your Cisco LAN switch and the network devices connected to it. It provides an easy and effective way to create a map of a switch and show which devices are connected to each port. Therefore it solves the problem of having to trace cables in order to see which devices are connected to each switch port.

Gook luck

mark.hodge Mon, 04/16/2007 - 15:24
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Another good software products are the SolarWinds toolsets. The switch port mapper is what you need for this. The eval version doesn't allow printing but you can screendump.


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