The Research And Implementation Of IP Network Real-Time Classes Quality Of Services

With the development of internet information applications, more and more enterprises and users send message on network, the amount of information is exploding, and this gives higher requirements to routers or firewall working in internet. What's more, with the starting of next generation network, multi-media applications like audio and video are rising, real-time classes data that need low delay is rising, how to guarantee the low delay of these applications is becoming more and more important. In order to deal with the message that beyond the network transmission capability, we have QoS (Quality of Services) technology, trying to satisfy different classes'transmission requirement. QoS provides quality guarantee for packets of different classes, but QoS can't stop network blocking. When network blocking is happened, packet management mechanism becomes important. Packet management mechanism decides the order of packet dealing and decides capability of network transmission in some degree.This paper researches technology the related to QoS, mainly includes technology indicators, functional components and two architectures proposed, and find out the limitations of IntServ and the advantages of DiffServ. Paper next analyzes the network blocking technology, includes TCP global synchronization and WRED technology to solve this problem and some kinds of packet management mechanism used on network currently, includes FIFO, PQ, CQ and WFQ. After this, this paper mainly research, improve and implement the Class Based Queuing mechanism, CBQ solve the "starvation" problem of PQ by using token bucket algorithm, and solve the fair scheduling problem by using SPFQ algorithm. CBQ classify packets to EF, AF and BE classes. Different scheduling strategy to different classes not only guarantees the low delay of real-time class packets, but also guarantees the bandwidth of other queues especially BE queue.But CBQ mechanism is not perfect, in practice we find that in low-speed link the long length packet has big affection to real-time class packets, so this paper proposes Fragment Insert technology to solve above problem. Splitting packets in data link layer and cache them into fragment temporary queue, sending a fragment every time to make sure that real-time packet is sent between the fragments can decrease the delay of real-time packet obviously. On the basis of above research, this paper proposes a comprehensive solution mixed CBQ mechanism and fragment insert, which can solve real-time packet quality of service, providing a solution that can be learned. Finally this paper implements the main points of this solution and make sure it can work well by some test.