Finding a MAC address on the network

[Scott Hanson]

Hello,

On an all Cisco Network if I know the MAC address of a device on the network but not what switch it is on is there anyway to find out the switch it is on and the port?

thanks in advance!

[Georg Pauwen]

Hello,

unless you have something like Cisco Network Assistant installed, you need to dig your way through to the switch where the host is connected. Let's say you are looking for MAC address ab12.cf34.aa21, on the router, issue the command:

show mac address-table | include ab12.cf34.aa21

The output will tell you the port of the connected device, e.g.:

ab12.cf34.aa21 DYNAMIC Fa0/2

If Fa0/2 is a trunk, go to that switch and follow the steps above, until you find the access port where the host with that MAC address is connected to...

[Scott Hanson]

Not the answer I was hoping for but thanks just the same

[balaji.bandi]

Why not write small shell script with scan all switches using snmp all devices in the network, if you have more switches in the network. can not required to go each switch and do show mac table.

BB

[Leo Laohoo]

If the client doesn't talk OUT then no MAC address will be registered on the core/distro switch.