Troubleshooting – Finding Laptop with only the IP Address

If you have access to the Cisco switch and know the IP address of the laptop, you can identify the port it’s connected to. Here are the steps you would typically follow:

1. Identify the MAC address of the laptop:

First, you need to find the MAC address associated with the given IP. You do this by checking the ARP (Address Resolution Protocol) table on the router.

Log in to the router and enter the command:

show ip arp | include <laptop's IP address>

This will output the MAC address of the device with the given IP.

2. Find the port where the laptop is connected:

Once you have the MAC address, you can then use that to find the port on the switch where the laptop is connected. Log in to the switch and enter the command:

show mac address-table address <laptop's MAC address>

or, depending on the IOS version:

show mac-address-table address <laptop's MAC address>

The output will include the port where the laptop is connected.

Please note that these commands assume that you’re using Cisco IOS. The exact commands can vary depending on the specific Cisco equipment and software version you’re using.