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New Member

Catalyst 4006 Port Question

Can anyone tell me how I can find out what port an IP address is on. I have a Laptop connected to my network. I have it's IP address, computer name and MAC Address. I would like to know how I go about finding what port this machine is on. Can anyone help?? Thanks

New Member

Re: Catalyst 4006 Port Question

Ping the ip address & then type sh arp

This will show the mac address resolved to the ip address and the port the mac address is associated with.

If you have other switches attached you may need to drill down thru them.

On some other switches you'll need to use a sh mac-address-table from enable mode to trace everything

good luck

New Member

Re: Catalyst 4006 Port Question

Depending upon your version of IOS, you can use the 'Output Modifiers' tool.

Try this:

Cat_4000#show arp | include x.x.x.x (where x.x.x.x is IP address)

Internet x.x.x.x 11 0002.7da7.affc ARPA Vlan1

This gives you the MAC address of the IP. To find the port where the MAC address is, you then need to enter:

Cat_4000#show mac-address-table | include 0002.7da7.affc

1 0002.7da7.affc dynamic ip,assigned GigabitEthernet2/1


You now know that IP address x.x.x.x is out of interface GigabitEthernet2/1! The 'Output Modifier' tool is a way of searching for specific information, for example, 'show arp' would show all entries and it would be a laborious task to search for a specific IP address. The 'Output Modifier' only shows the IP address info you require.

Although this works, there may be a quicker way which someone else might explain!


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