Ports MAC address

[michel.chevalier]

I am not a Cisco admin but, I need your help to find the MAC address of all 16ports on my cisco 2921 Router. I tried some commands but I did not succeed. Please help!

Thanks!

Michel

[Predrag Jovic]

Generally, there are 2 commands:

show mac-address-table
show mac address-table

on WAN  interfaces you can see learned mac addresses by issuing

sh arp
sh ip arp

[seanvaid]

Are you looking for mac address of the individual interfaces or the devices connected on the other end?

On a layer 2 device:

"show mac address-table" will show you mac addresses discovered on the ports

"show interface gig 0/1 | incl address" will show you mac of the interface itself, make sure to replace the gig 0/1 with whatever is relevant to you. 

[Predrag Jovic]

Faster solution to check MAC addresses of all interfaces. Instead of specifying one interface at the time
show interface gig 0/x | incl address
to check mac addresses of all interfaces at once can be used
sh interface | i Fast|Giga|Hardware
and also
show interface gig 0/1 | incl address
will show both IP address and MAC address (if IP address is assigned to interface)
and
sh interface | i Fast|Giga|address
would also should both MAC and IP address (if IP address is assigned to interface)

[seanvaid]

Awesome! I suck at piping, these will come in handy some day. 

Thanks.

[michel.chevalier]

Thank you all for your answer.

One more question, Is-it possible that there is no MAC for each port. I mean, I tough each port got a unique MAC, but there is some interface with number; like 1/1.10, or 1/1.12 with the same MAC address?!? 

[seanvaid]

The .10 or .12 are subinterfaces on a singular physical interface. 

Google subinterface and you will find a lot of valuable information. 

[Predrag Jovic]

MAC addresses are only locally significant (need to be unique on network segment).
Subinterfaces share MAC address, the same goes to SVIs.