Macrelated

MACrelated typically refers to topics associated with Media Access Control (MAC) addresses, which are unique identifiers assigned to network interfaces for communications at the data link layer of computer networks. MAC addresses enable devices on the same local network segment to identify one another and manage access to the shared medium.

A MAC address is usually 48 bits in length, displayed as six hexadecimal octets (for example, 00:1A:2B:3C:4D:5E). The first three octets constitute the Organizationally Unique Identifier (OUI), assigned to a device manufacturer by IEEE. Some interfaces support a 64-bit format (EUI-64) for extended addressing. Addresses can be globally unique or locally administered; the latter is indicated by a specific bit in the first octet and allows users to override the factory-assigned value for purposes such as privacy or testing.

In operation, MAC addresses function within local networks. Ethernet frames carry destination and source MAC addresses, and switches use these addresses to build MAC address tables that determine where to forward frames. IP addresses operate above MACs, with Address Resolution Protocol (ARP) mapping an IP address to a MAC address on IPv4 networks, and Neighbor Discovery performing a similar role in IPv6. MAC addresses can be broadcast (all ones) or multicast (group addresses) to reach multiple devices.

Security and privacy considerations include MAC spoofing, where a device adopts another’s MAC address to bypass controls or intercept traffic. MAC filtering is limited as a security measure, and modern networks employ additional controls such as 802.1X authentication and privacy features like MAC address randomization in some devices and protocols.

Note: MAC can also refer to Message Authentication Code in cryptography, a different concept outside the networking scope of MAC addresses.