How to find on which port a device is connected to a Cisco Switch

Finding a device connected to a Cisco switch

Posted by Humboldtux on Fri, Jun 26, 2015
In Netops
Tags cisco, ios, network

First, you need to get the MAC address of the device you are looking for. From a Cisco, if you know th IP of the device, you can query for it’s MAC like this:

# show ip arp

Then, display on which port is connected the MAC retrieved:

# show mac address-table address 123a.f74d.9999

Show info about the port the device is connected to:

# show running-config interface f0/1

If the info shows that it’s connected to another switch (mode trunk), show info about this neighbor device:

# show cdp neighbors f0/1 detail

Rinse and repeat, as necessary.