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Find a Mac-address

Find a Mac-address

Find a Mac-address

I've been asked for this question, and it beats me.

How can you find a MAC-address on which port in which swith in a LAN?

both in IOS and CATos commands.

RE: Find a Mac-address

To do it manually in IOS use the command:
show mac-address-table
This gives the complete table
If you want to find the mac address 00-00-12-55-fa-3e use:
show mac-address-table | include fa3e
Then use show interface status and/or show cdp neighbors to see where it connects to.

To do it maually in CatOS use the command:
show cam dynamic
Use the questionmark (show cam ?) to see the other available options.

To do it automated, use the "cammer" Perl script from our MRTG friend Tobias Oetiker.
(I assume you have Perl installed)
You can find this cammer Perl script at:
Be sure to read the cammer.readme.txt
Redirect the output to a textfile for further processing.

RE: Find a Mac-address

A way to do this in IOS is to use the following command or a variation of it depending on the version.

If you want to find mac address 00-00-12-55-fa-3e

show mac address-table | include fa3e

you will get an output sort of like this

   8    0000.1255.fa3e    DYNAMIC     Fa2/0/32

RE: Find a Mac-address

I always used:

show mac-address-table dynamic address 0000.1255.fa3e

which works fine for IOS.

Experience is a tough teacher.
The test comes first, the lesson comes later...

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