Cisco switches seem to allocate unique MAC address for each interface they have, this includes ports and vlan interfaces.
These unique MAC are derived from a "Base ethernet MAC Address", which can be found with:
MySwitch#show version ...snip... Base ethernet MAC Address : 70:10:5C:22:83:80
The interfaces MAC, then look like:
MySwitch#show interface FastEthernet0/1 Hardware is Fast Ethernet, address is 7010.5c22.8381 ...snip... MySwitch#show interface vlan87 Hardware is EtherSVI, address is 7010.5c22.83c6 ...snip...
Then, if I inspect a CDP packet received from a switch, the MAC address on the packet is the actual "port" MAC address.
Is there a reliable way to infer the switch "Base ethernet MAC Address" from receiving such a CDP interface MAC Address, so that I can use that "Base ethernet MAC Address" as a globally unique identifier for the switch device equipment on the network?