Detailed MAC address format

Ethernet Addressing

at the data link layer, data frames are usually dependent on MAC address for data exchange, it requires global uniqueness just like a public IP address, so that each host can be identified. So How does the MAC address do this? What is the format of it?

MAC address, English full name Medium accesscontrol, literal translation of media access controls , which is usually cured on each Ethernet network card (nic,network Interface Card). mac(Hardware) address long -bit (6 bytes), in hexadecimal format, describes the MAC address of the decimal place and its components.

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Example: 00-01-6c-06-a6-29 or 00:01:6c:06:a6:29

Organization Unique identifier ( OUI) is assigned to the manufacturer by the IEEE( Institute of Electrical and Electronics Engineers ), which contains the four digits. The manufacturers then use the remaining (EUI, extended unique identifiers) to assign each NIC they produce a globally unique global management address, which is typically purchased by a manufacturer of multiple OUI.

i/g ( Individual/group) bit, if i/g=0, is the MAC address of a device , that is, the unicast address; if i/g=1, is the multicast address ( multicast + Broadcast = multicast ).

g/L ( Global/local, also known as u/l bit, where U represents Universal) bit, if g/l=0, is the global administrative address, assigned by the IEEE, or, if g/l=1, the local administrative address, the address that the network administrator has specified to strengthen its management of the network.

for i/g and the g/L position, there are two kinds of statements, or two formats.

In the case of data transmission, it is transmitted in one place per byte, and one byte is passed to the next byte.

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First Kind , each byte high in front, low in the rear, i/g bit and the g/L The lowest and second lows in bytes, the highest bit is sent first, to the end or the highest bit

The second Kind , each byte is low in front, high in the rear, i/g bits and g/L The lowest bit and sub-low in bytes, the lowest bit is sent first, to the end or the lowest bit

The two seem different, but the result is the same, if you still can not understand the draft paper on the drawing, it is not difficult to understand.

This article is from the "1111" blog, please be sure to keep this source http://9723340.blog.51cto.com/9713340/1759570

Detailed MAC address format