As described in data link layer address, Ethernet uses MAC addresses for its layer 2 communication. Almost all the ports in a LAN have MAC addresses. And they all are unique. How they keep it unique? The fundamental is quite simple. MAC addresses are burnt in addresses and hence can’t be changed (In reality, I suspect they can be changed). Vendors making the ports assign each port a unique MAC Address. MAC address is a 48 bit address represented as 6 pairs of hexadecimal
codes. Some example of MAC addresses are:
D8-D3-85-00-6E-2D54-CB-AE-53-3D-09The first 3 bytes of a MAC address are associated with the vendor, or maker, other NIC. Each vendor has one or more unique sets of three bytes. These first 3 bytes are commonly called the organizationally unique identifier (OUI). And last 9 bytes has to be assigned by vendor. He can do it any manner but it has to be unique.
Note: You can check your computer’s MAC address by going to command prompt and issuing command
ipconfig /all