(Short for Media Access Control) is assigned at the factory to a network device
such as NIC. MAC address is protocol
independent. Layer 2 devices such as switches, and bridges use MAC address to
distinguish between different nodes in a network segment. Compare this with
Layer 3 devices such as router that use IP address for transporting packets
between different networks (or sub-networks).
3 addresses are logical addresses as they are assigned by the protocols, whereas
Layer 1 addresses are physical addresses, and can't be changed without changing,
for example, a network card (NIC).
A MAC address on a network is a 12-digit hexadecimal number (total 48
bits) in the format:
The first half of a MAC address contains the ID number assigned to the
The second half of a MAC address is the serial number assigned to the adapter
by the manufacturer.
You can find the MAC address on
your computer by typing "ipconfig /all" at the command prompt of a
Windows OS computer.
In the figure above, the value 00-C1-26-0D-DE-C9
represents the MAC address of the host named "system". Whichever
higher layer protocol you use, the MAC address remains the same. In the MAC
address given, 00-C1-26 is NIC manufacturer ID, and 0D-DE-C9 is the serial
number given to the adapter by the manufacturer.