Chapter 2 Qos Configuration; Qos Overview; Traffic; Traffic Classification - Huawei Quidway S3500 Series Operation Manual

Operation Manual - QoS/ACL
Quidway S3500 Series Ethernet Switches

Chapter 2 QoS Configuration

2.1 QoS Overview

In the traditional IP network, all the packets are treated equally without priority
difference. Every switch/router handles the packets following the First In First Out
(FIFO) policy. That is, they make best effort to transmit the packets to the destination,
not making any commitment or guarantee of the transmission reliability, delay or to
satisfy other performance requirements.
With the rapid development of computer network, people transfer more and more voice,
image and important data etc at real time which are sensitive to the bandwidth, delay
and jitter. This enriches the network sources. On the other hand, the network
congestion occurs more frequently, hence people require higher Quality of Service
(QoS) for the transmission over the network.
The Ethernet technology is the most widely used network technology nowadays.
Ethernet has been the dominant technology of various independent Local Area
Networks (LANs), and many LANs in the Ethernet form have been part of the Internet.
Moreover, along with the continuous development of the Ethernet technology, Ethernet
will become one of the major ways to access the common Internet users. In order to
implement the end-to-end QoS solution on the whole network, it is inevitable to
consider the question of how to guarantee the Ethernet QoS service. This requires the
Ethernet switching devices to apply the Ethernet QoS technology and deliver the QoS
guarantee at different levels to different types of signal transmissions over the networks,
especially those having requirements of shorter time delay and lower jitters.

2.1.1 Traffic

Traffic refers to all packets passing through a switch.

2.1.2 Traffic Classification

Traffic classification means identifying the packets with certain characteristics, using
the matching rule called classification rule, set by the configuration administrator based
on the actual requirements. The rule can be very simple. For example, the traffic with
different priorities can be identified according to the ToS field in IP packet header. There
are also some complex rules. For example, the information over the integrated link
layer (Layer-2), network layer (Layer-3) and transport layer (Layer-4), such as MAC
address, IP protocol, source IP address, destination IP address and the port number of
application etc can be used for traffic classification. Generally the classification
standards are encapsulated in the header of the packets. The packet content is seldom
used as the classification standard.
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Chapter 2 QoS Configuration