MAC Address Stands for “Media Access Control Address is a unique identifier for an Ethernet or network adapter over a network. it’s also sometimes referred to as hardware or physical address and burned-in address. The Media Access Control Address is manufactured into every network card, such as an Ethernet card or Wi-Fi card, and therefore cannot be changed. It distinguishes different network interfaces and is used for a number of network technologies, particularly most IEEE 802 networks, including Ethernet.
In the OSI model, MAC addresses occur in the Media Access Control Protocol sub-layer. Media Access Control Address represents a single NIC or Ethernet port, so these addresses are often called a unicast Ethernet address. The term unicast is simply a formal way to refer to the fact that the address represents one interface to the Ethernet LAN.
Each device Media Access Control Address should be unique in order to send/receive data successfully. When you’re connected to the Internet from your computer (or host as the Internet protocol thinks of it), a correspondence table relates your IP address to your computer’s Media Access Control Address (physical) address on the LAN.
The format of MAC Address
- Dell: 00-14-22.
- Cisco: 00-40-96.
- Nortel: 00-04-DC.
Types of MAC Address
- Unicast – A Unicast addressed frame is only sent out to the interface leading to specific NIC. If the LSB (a least significant bit) of the first octet of an address is set to zero, the frame is meant to reach only one receiving NIC. Media Access Control Address of the source machine is always Unicast.
- Multicast – Multicast address allow the source to send a frame to a group of devices. In Layer-2 (Ethernet) Multicast address, LSB (a 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 (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 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 address. Frames which are destined with MAC address FF-FF-FF-FF-FF-FF will reach to every computer belong to that LAN segment.
How to find a MAC address of network device?
- On Unix variants including Solaris and Linux support
- In Windows
- On a MacOS, one can find MAC address by opening “System Preferences”, then selecting “Network”.