Packet Switching Network Switching Technology

Internet is one of the most important information technologies developing at a highspeed in the last more than ten years. The users of Internet increase exponentially, and theInternet traffic increases dramatically. So, the demand for network bandwidth constantlyrises and is already far beyond the reach of current link and switching capacity. Along withthe emergence of multimedia and real time video-on-demand, the Internet users' request toquality of service also becomes more and more rigorous. Therefore, the research area ofInternet routers and switches has already become more and more popular. It results inmany remarkable achievements, Some international famous network equipment andservice corporations have competitively distributed faster to faster routers or switches Inthe research on high-speed routers; high-speed switch technologies are the basic and coresubjects. Although there are many different switch fabrics and scheduling algorithms, itsdevelopment has complied with some certain ways. It was a milestone that shared busswitch fabrics had been replaced by crossbar fabrics. Several pair of ports can exchangeinformation simultaneously on crossbar fabric, and also one port can efficiently transfermessages to several other ports on it. HOwever, when the number of port expands, fataldifficulties will occur since all Scheduling algorithms for crossbar fabric should becentralized. Benefit from the break through of very high speed Random Access Memories,shared memory fabrics seem to take place crossbar fabric on designing high capacityswitches in the near future. For the sake of extremely high Bandwidth of Random AccessMemories, the scheduling algorithms to shared memory fabrics are relatively simple. Thispaper improves the Longest Queue First algorithm, and present a new Output Queuealgorithm: Improved Longest Queue First algorithm.