EPON--网络中一种服务区分机制的算法研究.doc

PAGE 摘 要 近年来，随着科学技术的发展，通信骨干网络和局域网产生了巨大的变化。“最后一公里”的接入网部分已经逐渐成为通信骨干网络和高速局域网之间的瓶颈。在电信市场竞争日渐激烈的今天，传统的宽带接入已经不能满足广大用户的带宽需求。 以太无源光网络，即EPON( Ethernet Passive Optical Network )是无源光网络技术与以太网的结合。它具有兼容性能好、易扩展、低成本等等优点。因此，EPON被广泛的看作是下一代接入网最重要的选择之一。为了满足新应用对服务质量的要求，需要新的服务方式，也就是说需要引入新的互联网服务模式和一些能够支持QoS的机制。 不同的上行带宽分配算法对于EPON的服务质量的影响各不相同。动态分配技术是决定EPON网络性能的关键因素之一。本文首先对接入网的基本原理进行了一个简单的阐述。然后，在接入网的基础之上引入了EPON。最后，详细的介绍了EPON系统中的动态带宽分配算法（DBA）以及服务区分机制的概念。并由此引出了EPON中一种支持QoS的DBA。另外，文章还对EPON的ONU自动发现、ONU测距和动态带宽分配等关键技术进行了简单的介绍。在实际应用中，网络的服务质量对网络的运营来说至关重要。本文结合对经典的EPON动态带宽分配算法的研究，通过利用Visual C++仿真工具，得出了服务区分机制对EPON网络性能的影响。 【关键词】EPON 动态带宽分配算法 服务质量 ABSTRACT In recent years, with the development of technology, the telecommunication backbone netwok and the local netwok has changed a lot. The access network has become a bottle neck between high-capacity local network and the backbone netwok. With the increasing competition of the telecommunication market, the tradition accessed broadband can not adapt to the bandwidth needs of users. Ethernet passive optical network(EPON，Ethernet Passive Optical Network ) combines the passive optical network with the Ethernet technology. It has many merits such as good compatibility features, easy expansion, low-cost and so on. Thus, EPON was considered as one of the most important choice of the next generation access network. To meet the need of multimedia applications particular QoS control mechanism and new Internet service mode should be introduced. Different upward bandwith location algorithm has different impact on the QoS(quality of service) of EPON. The key of EPON is Dynamic Bandwidth Allocate (DBA). On the basis of access network which is stated in this article first，EPON is brought in. In the end,we have a detailed discuss on the Dynamic Bandwidth Allocate and DiffServ in EPON system,and by which a DBA supporting of QoS is introduced. The paper also made a simple introduction to the EPON primary technology, such as ONU auto discovery, ONU distance detect, dy