Finding Mac address on network

[dvanzee]

At my layer 3 switch I do a "show arp | in 192.168.0.X" and it comes back with a mac-address matching up with this ip, but when I try run a "show mac-address address" to find where this device is known on the network it doesn't register in the table. I went through all layer 2 switches, with the same result. Any ideas on how I can find this device?

L3 3750

L2 3550-35560

[mattcalderon]

did you verify that what is in the arp cache is current? Verify you can ping the IP you are looking for because it quite possibly could have aged out.

Sh mac-add | inc .xxx

is the best way i know of to trace a MAC through a network

[dvanzee]

Hi Matt,

Thanks for the reply, this is a pingable address.

[mattcalderon]

sho mac-add is case sensitive.

Do a "sho mac-add | inc xxx" and see what your output is. The last 3 of the hex MAC is case sensitive so put exactly what you find on a sho arp.