Network Interface Card

aliases:

A hardware device responsible for managing the communication between a PC system and it's connected network.

It does this by converting a digital data stream that can be sent along the transmission medium.

Physical Addressing

Each network interface card has a unique, identifying address called the Media Access Control or (MAC) address. The MAC address is burned into the read-only memory of the NIC, and it's a 48-bit hexadecimal number. No two NICs have a matching MAC address.

MAC addresses are generated by taking a unique six-digit sequence assigned by the IEEE that identifies the manufacturer of the NIC. The second half is a random value assigned to that MAC address.

There are two types of NIC identifiers. Defined by the IEEE, an EUI-48 (extended unique identifier) is a NIC's MAC address, but an EUI-64 uses a 64-bit address space.

Burned-in Addresses

While the IEEE has manufacturers assign MAC addresses into the NICs readonly memory, organizations can choose to toggle the Universal/Local bit on the NIC using the it's driver software or some network management software. It then becomes the network admin's responsibility to ensure that all nodes within the organization's network has a unique MAC address.

#XI