带宽控制策略及其在嵌入式系统中的应用研究-软件工程专业论文.docxVIP

华中科技大学硕士学位论文 华 中 科 技 大 学 硕 士 学 位 论 文 II II Abstract Network congestion has become an important issue with the rapid development of the Internet. Further，AQM(Active Queue Management) is hostpot in the current. TCP/IP protocol can’t ensure network transmit QoS(Quality of Service), but provide “better effort” service. Network Congestion is exist consequentially because the quantity of data been required to transmit is beyond the bottleneck bandwidth at present, so it is very important that congestion control mechanisms are used. Different communication requirements are need by different services. IP QoS research is to bring about in this situation. QoS module is one of the most important and competitive parts in the market products at present. There are 3 architectures primarily. (1)IntServ: using an important network control protocol named RSVP(Prior Resource Reserve Protocol). (2)DiffServ: QoS is provided by means of aggregate and PHB(per hop behavior). (3) MPLS (Multi-Protocol Label Switching): the flexible 3rd level IP routing and 2nd level switch techniques are perfectly integrated to make up for the faults of traditional network. There is special scope of each architecture. DiffServ architecture is chose for an effective and cost saving way in the condition that QoS architecture is in a simple physical environment and is set in embedded system. Compared to winCE embedded operating system, development was more easier when Linux has been chosen as operating platform of the system. The read-only cramfs file system has been chose as the Linux file system to consider the cost and security and so on. The TC(Traffic Control) packet module was the primary tool to make the QoS architecture comes true. TC packet module specifically which has lots of powerful qdisc algorithms and filters is the software packet to develop bandwidth control in Linux kernel appending. The most academic part of QoS is choosing or programming the basic module such as qdisc, III III cla