MAC

MAC Address Description

A MAC (Media Access Control) address is a unique identifier assigned to network interfaces for communications on the physical network segment. It’s a hardware address that identifies each device on a network. MAC addresses are used in the network’s media access control protocol sublayer of the OSI model.

MAC addresses are most often assigned by the manufacturer of a network interface card (NIC) and are stored in its hardware, such as the card’s read-only memory or some other firmware mechanism. A MAC address typically consists of six pairs of hexadecimal digits, for example, 00:1A:C2:7B:00:47.

Computer screen showing an impression of a MAC address

Basic Use of MAC Address

1. Network Communication: The primary role of a MAC address is to ensure that data packets reach the correct destination on a local network segment. It operates at Layer 2 (Data Link Layer) of the OSI model.
2. Device Identification: Each device on a network, like a computer, router, or printer, has a unique MAC address, which allows for its precise identification in the network.
3. Network Access Control: MAC addresses can be used for controlling access to a network. Network administrators may set up MAC address filtering to allow or deny network access to specific devices.
4. Data Framing: In Ethernet networks, MAC addresses are used in the framing of data packets. Each Ethernet frame contains both the source and destination MAC addresses to facilitate data transmission within the network.
5. Network Switching: Network switches use MAC addresses to forward data to the correct device on a LAN. When a switch receives a packet, it reads the destination MAC address and forwards the packet to the corresponding device.

Uniqueness and Limitations

• Uniqueness: MAC addresses are generally unique as they are assigned by the manufacturer. However, they can be spoofed or altered, which is a technique sometimes used in network attacks or for privacy reasons.
• Scope: MAC addresses are only relevant and unique within the scope of a single local network. They are not used for routing traffic between different networks across the internet – this is the role of IP addresses.

MAC addresses play a crucial role in the data link layer of network communication, ensuring that data packets are accurately delivered to devices within a local network.

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