Research And Implement Of The Key Technology For IP QoS Based On Network Processor

Along with the rapid development of network technology, the application ofInternet is wider. The network service also presents the characteristics ofdiversification. Thus the traditional real-time services have not already people'sneed. Immediately what to produce are various multi-media business such as,video, audio, the television meeting etc. with high request of real time. Thetraditional service of IP net can provide "do the best one can" only which can notsatisfy the request of low time delay .So the trend of IP provides service ofclassification and guarantee the quality of service.in network equipment.Thenetwork is developed rapidly, Router is the main network equipment and thecontrol unit is network processor, so the research and implement of the quality ofservice is important orientation.The principal content of this dissertation is Realization of the IP QoS(Quality of Service) based on network processor. According to the characteristicof network and the performance of network processor, a IP QoS system model isdesigned. The IP QoS in data transmit lay is mainly researched and realized, thevalidity of the QoS system proposed in this dissertation of is also proved inRouter.As a whole, the main research work is divided into four parts.In the first part: we design the IP QoS system model and describe each partof the system. Firstly, the principle and idea of the system is introduced, secondly,the position of system model in the Router is introduced. Every composing partof system model is expatiated and interrelated algorithms are intrduced. At thesame, it is pointed that the realization of IP QoS is in data transmit lay.In the second part: we describe the main algorithms of the IP QoS systemand the principle of the CAR (Committed Access Rate), ACL (Access ControlList), CBWFQ (Class-Based Weighted Fair Queue), WRED (Weighted RandomEarly Discard). In CAR algorithm, the functions of CAR is to restrict the flow ofcertain data packets, set the minimum bandwidth, perform the advanced decisionfor data packets that go beyond the bandwidth and indicate the correspondingparameters, the definitions of Token Bucket and conforming operation and excessoperation. It is pointed that CAR algorithm is a valid method to limit the rate ofdata packet.The data packets types that this system model involves mainly include IPv4,IPv6 and MPLS (Multi-protocol Label Switching). Subsequently, the structure ofIPv4 packet header, IPv6 packet header, MPLS packet header are explainedrespectively. The rule by which packet to queue is also given. The describedqueue methods of the data packets will be used in module of queue managementas an important part of IP QoS model theory.In the same way, the CBWFQ algorithm is introduced as a Class-BasedWeighted Fair Queue. The principle of the CBWFQ algorithm is described andcompartment between PQ (Priority Queue) and FIFO (First In First Out) is got.What should be proved is that CBWFQ is a valid method to divide the bandwidthby weight.At last in the second part, we describe the ACL and WRED algorithms. TheACL is an important method to classify the packet which also can transmit packetor deny the packet by policy set beforehand. In Network it need different datapackets to provide different service, so it is necessary to classify data packets,which the ACL algorithm can do validly.Though the queue manager block can do some work in this aspect, it needmore valid method to prevent network from the state of congestion. The WREDalgorithm is a valid method to prevent network from the state of congestion. First,we introduce the RED (Random Early Discard) algorithm and compare it with theWRED. The latter is more valid than RED algorithm. The WRED can preventqueue from the state of tail dropped and drop the packet randomly by weight, soit can prevent network from the state of TCP global synchronization.In the third part: we explain the hardware structure of IXP2400 and thecriterion of microcode. Then we describe the position of microcode in Routersoftware system. The position of QoS system in microcode system is alsodescribed. The realizations of each key technology for the IP QoS and themicrocode realization of the algorithm are all based on total design scheme whichis expatiated therefore. At last the ACL, the WRED, the CBWFQ and the CARalgorithms are all realized by microcode based on IXP2400 network processor.Some tables and flow charts for every block are given.In the forth part: we give the result that is got from running the QoS systemin Router with a real test environment. First, the hardware resource, the softwareresource and real test environment are introduced. The hardware resourceincludes the Router, which contains the network processor card and switch fabriccard. It also needs Router Test and two PC for controlling the Router and RouterTest respectively. The software resource includes VxWorks, software for RouterTest, SDK3.1 and other Router software. At last the result that has got from thereal test environment is analyzed. The result shows that OoS model proposed isvalid for sorting, filtrating, bandwidth limitation, congestion of state and serviceof classification. The dissertation pointed that the QoS system can reach therequirement of the functions and performance to guarantee the quality of service.This dissertation is achieved based on the network and network processortheory by designing in the laboratory and testing on the spot. The QoS systemmodel is valid for sorting, filtrating, bandwidth limitation, congestion of state andservice of classification. The QoS system model can run at wire-speed of 2.5Gb/sand get rid of the influence of large routing tables and large routing jitter onforwarding performance. It can reach the requirement of the functions andperformance of core router and be used widely in high performance routingequipment.