User Manual - Configuration Guide (Volume 3)

Chapter 1

Versatile Routing Platform

QoS overview

Chapter 1 QoS Overview

1.1 About QoS

In traditional IP networks, all packets are processed equally. Each router processes the packets with first-in first-out (FIFO) policy. It sends the packet to the destination in the mode of best-effort, but the throughput, delay, delay jitter and packet discarding rate cannot be predicted. The situation can be very perfect, or be very bad, and it can only be determined by the state of the network. However, people raise higher demand for the network along with the rapid development of computer network. As more and more voice, image and important data are transmitted over the network, which are sensitive to bandwidth, delay, jitter and real-time features, network resources now become increasingly diversified. At the same time, the service quality also becomes an important issue. People expect that they can get enough guarantee in the aspects of the throughput, delay, delay jitter and discarding rate of packets, so that their special requirements on the special services can be satisfied. People also expect that they could obtain customized service quality according to the client types. One way to solve this problem is to increase the bandwidth. But bandwidth increase is limited and costs a lot. The problem can only be solved to a certain extent.

QoS (Quality of Service) indicates the integration of a series of technologies that permit users to get predictable service quality in the aspects of throughput, delay jitter, delay, and packet discarding rate. QoS (Quality of Service) provides network service function with different service quality according to different demands. It can be said that the capability of providing QoS is the basic requirement for future IP networks.

1.2 Three service types of QoS

Usually, the service of QoS is classified into the following three types:

I. Best-effort Service

Best-effort Service indicates to work with “the best effort”, but it cannot guarantee the service quality.

II.Integrated Service

This service type uses signaling mechanism to inform the data flow passing route to obligate resource, so it can implement quality guarantee very well. Bur when the size of the network is large, the cost is high, and then the integrated service is usually applicable for the edge of network. The signaling used to transfer QoS request is RSVP (Resource ReSerVation Protocol), which informs the QoS request of application to the router.

The integrated service provides the following two types of services:

1)Guarantee: i.e., to provide guaranteed bandwidth and delay limit to satisfy the application request

2)Load control: to guarantee that it would provides the packets services almost the same as those when the network is not overloaded even if the network is

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Huawei v200r001 user manual QoS Overview, About QoS, Three service types of QoS, Best-effort Service, II.Integrated Service