п»їUnit 4 Research Project Report
IEEE802 standard series protocol, your data link part includes a logical link control (LLC) sublayer and the press access control (MAC) sub-layer which is located between the MAC PC layer as well as the physical LLC, which allows edition to different LLC media get technology and physical multimedia. MAC sublayer as a separate, they will not replace the impact of the media get method and higher level protocols. MAC disassembly of data and media gain access to management of two segments, the completion of the data framework encapsulation, re-opened send and receive functions. Ethernet body encapsulation file format as displayed in Stand 1, the place that the destination addresses, source treat, length as well as type field and the data generated by the four layer protocol module when sending data support frames, data encapsulation module immediately adding info to be transmitted in the 1st seven octet of preamble and a delimiter octet and add by the end of the data transfer byte dispatched four cyclic redundancy examine code, in case the data span is less than 46 bytes, the data is instantly filled in in an attempt to achieve the minimum length required once receiving info frame, the info will be instantly discarded detachable module preamble and delimiter two fields.
Media access management module main CSMA / CD (carrier sense multiple gain access to with crash detection) protocol. CSMA as well as CD is actually a distributed MAC protocol that enables multiple network stations (nodes) can be distributed transmission moderate. Sending data when the shape, the initially node listens for a carrier, when the method is idle starts when the transmission framework, if incompatible with other nodes in the transmitting process, each node should be given is a 32-bit transmission obstructing signals to boost the size of the conflict, in order to inform the bus turmoil has took place on each web page, and then re-random delay period contention moderate, and then resend the data framework.