Mac (Media Access Control) addresses, or MAC address, hardware location, are used to define the locations of network devices. In the OSI model, the third layer of network layer is responsible for the IP address, the second layer

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The Http://baike.baidu.com/view/69334.htm MAC (Media Access Control) address, or MAC location, is used to define the locations of network devices. In the OSI model, the third layer of the network layer is responsible for the  IP address, while the second layer of data link is responsible for MAC addresses. Therefore, a host will have an IP address, and each network location will have a Mac addressing that is exclusively owned by it. The   mac (Medium/media Access Control) address, or MAC address, physical address, is used to represent the identifier of each site on the internet, in hexadecimal notation, with a total of six bytes (48 bits). Of these, the first three bytes are the code (high 24 bits) assigned by the registration Authority RA of the IEEE to different manufacturers, also known as the "unique identifier" (organizationally unique Identifier), and the last three bytes (low 24-bit) Adapter interfaces that are assigned to production by each manufacturer are called extension identifiers (uniqueness). A block of addresses can generate 2^24 different addresses. The MAC address is actually the adapter address or adapter identifier EUI-48.   mac (medium/mediaaccess control, media access control) MAC address is included in the Networkinterfacecard (network card, NIC). The MAC address, also called the hardware address, is made up of 48 bits/bit long (6 bytes/byte,1byte=8bits) and 16 binary digits. 0-23 bits are called organization unique identifiers (organizationally unique, Is the identification of the node that identifies the LAN (LAN). 24-47 bits are assigned by the manufacturer themselves. The 48th bit is the multicast address flag bit. The physical address of the network card is usually the EPROM (a flash memory chip, which can be erased by the program) that is burned into the NIC by the network card manufacturer, and it stores the address of the computer on which the data was transmitted and the host that received the data. That is, in the physical transmission of the network at the bottom of the process, through the physical address to identify the host, it is generally the only global. For example, the famous Ethernet card whose physical address is a 48bit (bit) integer, such as: 44-45-53-54-00-00, is stored in a machine-readable way into the host interface. The Ethernet Address Management Agency (IEEE) (IEEE: The Association of Electrical and Electronics Engineers) divides Ethernet addresses, or 48-bit combinations, into separate, contiguous address groups, and manufactures Ethernet network card manufacturers to purchase one group, each individuallyEthernet card is assigned to the address. The image says that the MAC address is just like the ID number on our ID card and has global uniqueness. The     feature is unique as an IP address. Each network card has its own MAC address, manufacturers have decided when the production.

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Mac (Media Access Control) address, or MAC addresses, hardware location, used to define the locations of network devices. In the OSI model, the third layer of network layer is responsible for the IP address, the second layer