Types of MAC Address –
- Unicast – A Unicast addressed frame is only sent out to the
interface leading to specific NIC. If the LSB (least significant bit) of
first octet of an address is set to zero, the frame is meant to reach
only one receiving NIC. MAC Address of source machine is always Unicast.
- Multicast – Multicast address allow the source to send a
frame to group of devices. In Layer-2 (Ethernet) Multicast address, LSB
(least significant bit) of first octet of an address is set to one. IEEE
has allocated the address block 01-80-C2-xx-xx-xx (01-80-C2-00-00-00 to
01-80-C2-FF-FF-FF) for group addresses for use by standard protocols.
- Broadcast – Similar to Network Layer, Broadcast is also
possible on underlying layer( Data Link Layer). Ethernet frames with
ones in all bits of the destination address (FF-FF-FF-FF-FF-FF) are
referred as broadcast address. Frames which are destined with MAC
address FF-FF-FF-FF-FF-FF will reach to every computer belong to that
LAN segment.
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