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Question about finding an IP address on a network

I was wondering if there is a simple way of tracking down what port an IP address lives on in a network.

I some times recive calls that an IP address on my network is flooding a virus out to another company. I have about 600 PC's in my cisco network and would like to know if their is an easy way of doing this.                  

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New Member

Question about finding an IP address on a network

look in dhcp for the IP address, find the corresponding MAC address.

then do a show mac address table xxxx.xxxx.xxxx

that will tell you the port that it is plugged into

Question about finding an IP address on a network

Assuming you have a Distribution > Access Switch topology.

Login to your distribution switch and ping the device.

#ping 10.1.1.1

Then look in the ARP cache to obtain the MAC address:

#show ip arp 10.1.1.1

Then look in the MAC address table for that MAC address to find which Access switch the host is connected to:

#show mac address-table | i 1234:5678:abcd

This should give you an outgoing port number which will be a link to one of your access switches. To find out which switch look at the CDP info for that port.

#show cdp neighbout Gi1/1

Once you know the Access Switch the host is connected to, login to that switch and look in the MAC address table again:

#show mac address-table | i 1234:5678:abcd

Assuming there are no daisy chained switches, the port which is shown in the MAC table should be the port your hos is connected to.

Cheers

New Member

Question about finding an IP address on a network

Thank you very much for the response very good steps and it did help

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