Ethernet Addressing (MAC)

• Ethernet Address is also called MAC Address (Media Access Control).

• MAC Address is 6 Bytes, 48 bits Hexadecimal Address.

• This MAC Address is made up of 6 Sets & each Set includes 8 bits of Hexadecimal characters separated by periods.

• MAC Address is pre-programmed in every NIC card.

• IEEE Assigns the first 3 Bytes unique to the NIC card called the Organizationally Unique Identifier (OUI). And the manufacturer assigns the remaining 3 Bytes unique to every NIC card that they manufacture.

• In this way, No two NIC cards will have the same MAC Address. Hence MAC Address is also called a Unicast Ethernet Address, LAN address, Ethernet address, hardware address, burned-in address, physical address & universal address.

  6 Bytes (48 Bits) MAC Address:

  OUI	Vendor
  24bits	24bits
  00 60 2F	3A 07 BC
  (6 Hex digits)	(6 Hex digits)

Group Address:

Apart from the Unicast Ethernet Address, Ethernet also uses Group Addresses which are divided into two categories:

• Broadcast Address:

  • Frame sent to this address will be delivered to all the devices of that LAN. It is FF:FF:FF:FF:FF:FF

• Multicast Address:

  • Frame sent to this address will be copied & delivered to a group belonging to that specific Multicast address & not to all the devices.

  Reference:

  CCNA 200-301 OCG, Volume 1, Pg. 50-51 - Wendell Odom.