07-18-2017 06:07 AM - edited 03-08-2019 11:22 AM
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
07-18-2017 07:56 AM
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
07-18-2017 07:57 AM
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.
07-18-2017 08:15 AM
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)
07-18-2017 08:48 AM
Awesome! I suck at piping, these will come in handy some day.
Thanks.
07-18-2017 12:40 PM
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?!?
07-18-2017 12:47 PM
The .10 or .12 are subinterfaces on a singular physical interface.
Google subinterface and you will find a lot of valuable information.
07-18-2017 01:30 PM
MAC addresses are only locally significant (need to be unique on network segment).
Subinterfaces share MAC address, the same goes to SVIs.
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