A switch will forward a unicast frame through all of its ports (except for the port that originated the frame) if the switch has no knowledge of which port leads to that MAC address, or just to the proper port if it does have knowledge. A unicast frame is transmitted to all nodes within the collision domain, which typically ends at the nearest network switch or router. This type of transmission is called unicast. If the least significant bit of the most significant octet of an address is set to 0 (zero), the frame is meant to reach only one receiving NIC. Therefore, it is a locally administered address. In the example address 06-00-00-00-00-00 the most significant byte is 06 (hex), the binary form of which is 00000110, where the second-least-significant bit is 1. If it is 1, the address is locally administered. If the bit is 0, the address is universally administered.

This bit is also referred to as the U/L bit, short for Universal/Local, which identifies how the address is administered. Universally administered and locally administered addresses are distinguished by setting the second- least-significant bit of the most significant byte of the address.

Locally administered addresses do not contain OUIs. A locally administered address is assigned to a device by a network administrator, overriding the burned-in address. The IEEE has a target lifetime of 100 years for applications using MAC-48 space, but encourages adoption of EUI-64s instead. The following three (MAC-48 and EUI-48) or five (EUI-64) octets are assigned by that organization in nearly any manner they please, subject to the constraint of uniqueness. The first three octets (in transmission order) identify the organization that issued the identifier and are known as the Organizationally Unique Identifier (OUI). A universally administered address is uniquely assigned to a device by its manufacturer. Addresses can either be universally administered addresses or locally administered addresses. This 48-bit address space contains potentially 248 or 281,474,976,710,656 possible MAC addresses.Р”Р„ll three numbering systems use the same format and differ only in the length of the identifier. The original IEEE 802 MAC address comes from the original Xerox Ethernet addressing scheme. Another convention used by networking equipment uses three groups of four hexadecimal digits separated by dots (. This form is also commonly used for EUI-64. The standard (IEEE 802) format for printing MAC-48 addresses in human-friendly form is six groups of two hexadecimal digits, separated by hyphens ( -) or colons ( :), in transmission order (e.g. The IEEE claims trademarks on the names EUI-48 and EUI-64, in which EUI is an abbreviation for Extended Unique Identifier. MAC addresses are formed according to the rules of one of three numbering name spaces managed by the Institute of Electrical and Electronics Engineers (IEEE): MAC-48, EUI-48, and EUI-64. This can be contrasted to a programmed address, where the host device issues commands to the NIC to use an arbitrary address.Р”Р„ network node may have multiple NICs and each must have one unique MAC address per NIC. It may also be known as an Ethernet hardware address ( EHA), hardware address or physical address. If assigned by the manufacturer, a MAC address usually encodes the manufacturer's registered identification number and may be referred to as the burned-in address ( BIA). MAC addresses are most often assigned by the manufacturer of a network interface controller (NIC) and are stored in its hardware, such as the card's read-only memory or some other firmware mechanism. Logically, MAC addresses are used in the media access control protocol sublayer of the OSI reference model. MAC addresses are used as a network address for most IEEE 802 network technologies, including Ethernet.

Uses several databases including NMAP, IEEE Official List, Wireshark Info, and more.Р”Р„ media access control address ( MAC address) is a unique identifier assigned to network interfaces for communications on the physical network segment.Partial searches are accepted: 001c, 2359:92.Discover which company built a networked interface by MAC Address.

Cisco mac address notation