Problem:

How to Locate the Cisco Switchport of a Server based on IP Address



Solution:


Locating computers or servers is a task I often do, and this is a tutorial on how I do it.

I have mentioned the do command, and mentioned it again in my 5 Magic Cisco Tips and Tricks article.

I am now going to give you more of a tutorial!

Locating a machine on switch port in a larger Cisco network
If you only have the IP address, just run this command:

show ip route *ipaddress*

The router will now tell you which interface this subnet is connected to.

In a usual setting you might have routed a larger block of addresses to for example a routing switch.
If this is the case, you will need to investigate layer 3 further down to that switch/router.

When you have found the IP address as directly connected issue this command to look up the MAC address in the ARP table.

show ip arp | include *ipaddress*

This will output the MAC address for this IP address, you can use this with this command:

show mac address-table | include *macaddress*

You will now see which port this hardware address is connected to.

In case you have a switch connected, you will need do the show mac address-table command on that switch also.

You can often identify switches by doing a show mac address-table interface *port*
If this gives a long list of MAC addresses with the TYPE dynamic, this is probably a switch.