The Research Of Bandwidth Allocation Algorithm And Safety In EPON Basing On OPNET

With the rapid development and popularity of Internet, core network is rapidly evolving to Gigabit Ethernet, while the rate of end-user is also developing with each passing day. However, the access network has made little progress which has become the bottleneck of the whole network. As a result, the access network technology has been attached more and more importance. With the emergence of optical access network technology, the bottlenecks of access network have been greatly improved, while passive optical network was recognized as the preferred technology for next-generation optical access network. As the meanwhile, Ethernet Passive Optical Network (EPON) technology represents the latest trend and is the hot spots of current research, which is considered as the primary means of passive optical network.In this paper, two key technologies in EPON system are investigated which are bandwidth allocation algorithmon and the the safety. Existing dynamic bandwidth allocation(DBA) scheme is introduced and a novel DBA algorithm over QoS is presented,which has dual-clocking, based on the classify character of Bandwidth Guarantee Polling(BGP ) algorithm.The novel OLT-based polling scheme has a fixed polling cycle(2ms). ONU's buffer receives different data packets from user,and these packets are classified and then placed into their corresponding appropriate priority queue.queue.It is shown from the simulation results that the algorithm improves bandwidth utilization of uplink and ensures the QoS of different services and shows satisfied delay performance. In addition, another novel adaptive dynamic programmable DBA scheme is discussed, based on the implementing of DBA in actual system of EPON. The scheme supports multiple services and provides different bandwidth service guarantees for different service such as fixed, guaranteed and extended bandwidth service. The major achievements are outlined as follows:1) In the first chapter, the key technologies in EPON and the corrent situation of the access network are briefly introduced.2) In the second chapter, the basic theory about EPON are summerized, and main parts of EPON and its functions, EPON key technology, as well as existing problems are mainly analysised.3) In the third chapter, the bandwidth allocation algorithm for EPON and safety are mainly analyzed and discussed, and the existing problems in bandwidth allocation algorithm are furtherly clarified. At the same time, existing security technology of EPON is also provided.4) In the fourth chapter, dual-clocking algorithm and adaptive dynamically programmable algorithm and new security technology is put forward basing on previous chapters.5) In the fifth chapter, we summarize and conclude the whole dissertation.