[Cisco Switch] Base Ethernet MAC Address

Trên Cisco Switch (29xx, 35xx …) có 1 địa chỉ Base Ethernet MAC Address ( gọi tắt là Base MAC), như sau:

SW#show version

…

The password-recovery mechanism is enabled.
384K bytes of flash-simulated NVRAM.
Base ethernet MAC Address: 00:14:69:C3:CC:00
Motherboard assembly number: 73-8100-09
Power supply part number: 341-0029-03
Motherboard serial number: CAT09211730
Power supply serial number: LIT090509J

…

SW#show mac address-table
Mac Address Table
——————————————-

Vlan    Mac Address       Type        Ports
—-    ———–       ——–    —–
 All    0014.69c3.cc00    STATIC      CPU
 All    0014.69c3.cc01    STATIC      CPU
 All    0014.69c3.cc02    STATIC      CPU
 All    0014.69c3.cc03    STATIC      CPU
 All    0014.69c3.cc04    STATIC      CPU

…

Thông thường, trên các switch layer 2, địa chỉ MAC của port = base MAC + port_id. Ví dụ:

SW#show int f0/1 | include bia
  Hardware is Fast Ethernet, address is 0014.69c3.cc01 (bia 0014.69c3.cc01)

SW#show int f0/2 | include bia
  Hardware is Fast Ethernet, address is 0014.69c3.cc02 (bia 0014.69c3.cc02)

Base MAC cũng là MAC ứng với SVI (switch virtual interface). Ví dụ:

SW1#show int vlan 100 | include bia
  Hardware is EtherSVI, address is 0014.69c3.cc00 (bia 0014.69c3.cc00)
SW1#show int vlan 200 | include bia
  Hardware is EtherSVI, address is 0014.69c3.cc00 (bia 0014.69c3.cc00)

Địa chỉ MAC trong BID (dùng cho STP) cũng là base MAC.