To communicate or transfer data from one computer to another, we need an address. In computer networks, various types of addresses are introduced; each works at a different layer. A Mac Address, which stands for Media Access Control Address, is a physical address that works at the Data Link Layer
- Mac Addresses are 48-bit Hexadecimal Address embedded into Network Interface Cards during manufacturing
- In 48-bit The first three octets are used as the OUI or Organisationally Unique Identifier. These MAC prefixes are assigned to each organization or vendor by the IEEE Registration Authority Committee. Last 3 octets usually assigned sequentially
- In the IEEE 802 standard, the data link layer is divided into two sublayers:
- Logical Link Control (LLC) Sublayer
- Media Access Control (MAC) Sublayer
Some example of OUI of known vendors are:
3C:D9:2B - Hewlett Packard
There are three types of MAC addresses:
- Unicast MAC Address: A Unicast-addressed frame is only sent out to the interface leading to a specific NIC. If the LSB (least significant bit) of the first octet of an address is set to zero, the frame is meant to reach only one receiving NIC. The MAC Address of the source machine is always Unicast.?
- Multicast MAC address: The multicast address allows the source to send a frame to a group of devices. In Layer-2 (Ethernet) Multicast address, the LSB (least significant bit) of the first octet of an address is set to one. IEEE has allocated the address block 01-80-C2-xx-xx-xx.
- Broadcast MAC address: Similar to Network Layer, Broadcast is also possible on the underlying layer( Data Link Layer). Ethernet frames with ones in all bits of the destination address (FF-FF-FF-FF-FF-FF) are referred to as the broadcast addresses.
How to find Mac Address in Windows:
Command For MAC Address in Linux:
