Media access control(mac)

Media access control defines how data frames in medium for transmission. In shares the same bandwidth of the link of connection medium access is "first come first serve". Physical addressing here are defined, the logical topology (signal by physical topology path) also here are defined. Circuit control, error notice (not correct), frame relay sequence and optional flow control in the son layer realization.

Section annotated

This agreement is located in the seven layers of the OSI agreements in the data link layer, the data link layer is divided into the upper logical link control (LLC), and lower the MAC (media access control), MAC is mainly responsible for the control and connection physical physical media. In sending data, MAC protocols can make decide if you can send data, if can send will give data plus some control information, will eventually data and control information to the format prescribed by sending to physical layer, In receiving data, MAC protocols first judgment input information and if an delivery errors, if there are no mistakes, then remove the control information sent to the logical link control (LLC) layer.

application

Whether in conventional wired local area network (LAN) or in the popular wireless local area network (WLAN), MAC protocols were widely. In the traditional LAN, various transmission medium of the physical layer to correspond to the corresponding MAC layer, currently in widespread use of the IEEE 802.3 networks is the MAC layer standard, using CSMA/CD access control mode; While in wireless LAN, MAC corresponding standards for IEEE 802.11, whose work means USES DCF model (distribution control) and PCF (center control). 

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.