Design And Implementation Of The Communition Protocol Between The High-End Router' POS Interface Card And The Main Card

With the rapid development of Internet and information network, the routers as an important network equipment begin to update and develop constantly, meanwhile, many wan technologies also arise at the historic moment. POS (Packet Over SONET/SDH, also called IP Over SONET/SDH) technology developed rapidly with the progress of SDH (Synchronous Digital Hierarchy) optical transmission technology. At present, POS interfaces have been indispensable line interfaces of various routers and provide POS access ability for routers. making POS interfaces being applied widely.More and more enterprises and manufacturers are paying attention to the research on design proposals of POS wan interface cards.According to a communication carrier's demands of high-end routers'POS interface card, on the basis of analyzing the present design schemes of POS interface card and the former architecture of high-end routers, this paper firstly introduced the background and significance of this research, as well as the home and abroad state of POS interface card, expounded the selection of design scheme of POS wan interface card, chose a design scheme of POS interface card based on network processor on the basis of analyzing the architecture of high-end routers, the design principles of interface card and the two design schemes of POS interfaces cards.Then, it analyzed and studied the communication principles between interface card and master card, designed the communication protocol schemes and every modules of the card communications, and designed the message frame formats of communication protocol by means of the rules of 802.3 ac which was approved by the IEEE in 1998and PPP protocol. Finally, it explicitly analyzed and studied each child module, which were carried out in the Vxworks embedded real-time operating system and its Tornado integrated development environment using language C, finished the realization of communication protocol between interface card and mater card, and tested the functions of communication protocol by means of the network testing equipment and environment provided by companies, carried out the system testing after the whole project's realization, the results showed that the communication protocol was expected to reach expectant communication goals, solved the communication problems between interface card and master card, ensured the stable operation of POS interface card on the high-end routers.