Research On Diffserv Multicasting Strategy Based On Distributed Resource Management

With the evolution of Internet from transmission network which transmits simplex data to transmission network which transmits multimedia information such as data, audio and image, how to provide satisfying QoS for users has become an important and realistic problem. DiffServ model has become preferred mechanism for QoS problem; moreover, applying multicasting technology upon Internet can save the bandwidth of backbone network and promote the resource utilization, which also is very important under the circumstance of current network multimedia application being on the rise. In terms of performance, DiffServ and multicasting are complementary technologies, DiffServ provides a scalable QoS solution, and multicasting provides an effective approach which can conserve network resource, the combination of both has become a necessary trend. However, the combination of two technologies is a non-trivial task due to architectural difference between DiffServ and multicasting, and will bring some conflicts. How to effectively combine DiffServ with multicasting has received more attention from native and foreign study students.This thesis focuses on how to effectively combine DiffServ with multicasting, and proposes an approach DMSBD (DiffServ Multicasting Strategy Based on Distributed resource management). Firstly, DMSBD adopts the distributed resource management manner which needs edge nodes as Resource Managers (RMs) to manage the resource in DiffServ domain so that it avoids these problems, such as single-node invalidation and link bottle-neck, which are introduced by centralized resource management manner. The QoS request of new member which requests to join multicast group must be checked through by RM, and then can take legal priority, or else the new member can only take priority which is lower than BE, at the same time, it also solves the NRS (Neglected Reservation Sub-tree) Problem. Secondly, the approach adopts the receiver-driven idea to establishe a QoS request signal mechanism, and uses re-mark method so that forwarding nodes know the QoS requests of new member clearly, thus it can solve efficiently heterogeneous multicasting group problem and promote scalability. Finally, the thesis presents simulation studies about DMSBD on NS2, and compares DMSBD with LE (Limited Effort) approach and traditional approach, the result indicates that although DMSBD has more signalings than pre-proposed approaches, it is worth obtaining more space conservation through expending some network layer'cost. In a word, DMSBD is an approach effectively solves the problems such as scalability problem, NRS problem and heterogeneous multicasting group problem, which are introduced by the simple combination of DiffServ and multicasting, and it is an approach with low cost and high scalability.