Network Addressing

Network devices use two different address types:

• The MAC address. The MAC address functions in the data link layer (Layer 2). MAC addresses are used in communicating with the closest device (a hop).

• The IP address. The IP address is a network layer (Layer 3). IP addresses are used when communicating with other computers on the LAN or Internet.

MAC Addresses

You cannot help but have a unique MAC because the first half of its 48-bit address (the first three octets in a hexadecimal address) is the organizational unique identifier (OUI). Every NIC manufacturer gets one. The last half is assigned by that company, like a serial number. The MAC address 00-0C-41-68-B2-85 means that it is made by Cisco Linksys. (68-B2-85 is the number that Cisco Linksys gave that NIC.)