MAC Address(Media Access Control)

MAC (Media Access Control) address, also known as MAC address, hardware address, used to define the location of network devices. In the OSI model, the third layer is responsible for IP address of the network layer, the second layer data link layer is responsible for the MAC address. Therefore, there will be a host IP address, and location of each network will have a special part of its MAC address.
MAC (Medium / MediaAccess Control, media access control) MAC address is burned in NetworkInterfaceCard (NIC) in the. MAC address, also known as the hardware address is 48 bits long (6 bytes), 16 hex digits. 0-23 bit is called the organizationally unique, is to identify the LAN (Local Area Network) .24-47 bit node identifier assigned by the manufacturers themselves. The first 40 is a multicast address flag. Network card physical address is usually burned into the NIC card manufacturers EPROM (one kind of flash memory chips, usually through the program erase), it is transferring data stored in the real data which identifies the computer and sent the host to receive data address.
 In other words, the underlying physical transmission network, is through the physical addresses to identify hosts, it is generally the only global. For example, the well-known Ethernet card, its physical address is 48bit (bits) integer, such as :44-45-53-54-00-00, stored in machine-readable form in the host interface. Ethernet address management (in addition to the outer tube also control other) (IEEE) (IEEE: Institute of Electrical and Electronics Engineers) to the Ethernet address, that is, different combinations of 48 bits, divided into several independent groups continuously address production Ethernet network card for the purchase of one group of manufacturers, concrete production, one by one unique address assigned to the Ethernet card.
Said image, MAC address as we ID card ID number, global unique.