For topologies with a collision domain (bus, ring, mesh, point-to-multipoint topologies), controlling when data is sent and when to wait is necessary to avoid collisions.
#Access control mac mac
the MAC adds a syncword preamble and also padding if necessary), adds a frame check sequence to identify transmission errors, and then forwards the data to the physical layer as soon as the appropriate channel access method permits it. When sending data to another device on the network, the MAC sublayer encapsulates higher-level frames into frames appropriate for the transmission medium (i.e. Although the MAC block is today typically integrated with the PHY within the same device package, historically any MAC could be used with any PHY, independent of the transmission medium. In turn, the medium access control block is formally connected to the PHY via a media-independent interface. Thus any LLC sublayer (and higher layers) may be used with any MAC. Within the hierarchy of the OSI model and IEEE 802 standards, the MAC sublayer provides a control abstraction of the physical layer such that the complexities of physical link control are invisible to the LLC and upper layers of the network stack. For compatibility reasons, LLC is optional for implementations of IEEE 802.3 (the frames are then "raw"), but compulsory for implementations of other IEEE 802 physical layer standards. These two sublayers together correspond to layer 2 of the OSI model. EtherType, 802.1Q VLAN tag etc), while the MAC provides flow control and multiplexing for the transmission medium.
Within the data link layer, the LLC provides flow control and multiplexing for the logical link (i.e. The MAC sublayer and the logical link control (LLC) sublayer together make up the data link layer. In IEEE 802 LAN/MAN standards, the medium access control ( MAC, also called "media access protocol" ) sublayer is the layer that controls the hardware responsible for interaction with the wired, optical or wireless transmission medium.
0 kommentar(er)
