Operation Manual – QoS-QoS Profile
H3C S3100 Series Ethernet Switches
Chapter 1 QoS Configuration
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Chapter 1 QoS Configuration
1.1 Overview
1.1.1 Introduction to QoS
Quality of Service (QoS) is a concept concerning service demand and supply. It reflects
the ability to meet customer needs. Generally, QoS does not focus on grading services
precisely, but on improving services under certain conditions.
In an internet, QoS refers to the ability of the network to forward packets. The
evaluation on QoS of a network can be based on different aspects because the network
may provide various services. Generally, QoS refers to the ability to provide improved
service by addressing the essential issues such as delay, jitter, and packet loss ratio in
the packet forwarding process.
1.1.2 Traditional Packet Forwarding Service
In traditional IP networks, packets are treated equally. That is, the FIFO (first in first out)
policy is adopted for packet processing. Network resources required for packet
forwarding is determined by the order in which packets arrive. All the packets share the
resources of the network. Network resources available to the packets completely
depend on the time they arrive. This service policy is known as Best-effort, which
delivers the packets to their destination with the best effort, with no assurance and
guarantee for delivery delay, jitter, packet loss ratio, reliability, and so on.
The traditional Best-Effort service policy is only suitable for applications insensitive to
bandwidth and delay, such as WWW, file transfer and E-mail.
1.1.3 New Applications and New Requirements
With the expansion of computer network, more and more networks become part of the
Internet. The Internet gains rapid development in terms of scale, coverage and user
quantities. More and more users use the Internet as a platform for their services and for
data transmission.
Besides the traditional applications such as WWW, E-mail, and FTP, new services are
developed on the Internet, such as tele-education, telemedicine, video telephone,
videoconference and Video-on-Demand (VoD). Enterprise users expect to connect
their regional branches together using VPN techniques for coping with daily business,
for instance, accessing databases or manage remote equipments through Telnet.
All these new applications have one thing in common, that is, they have special
requirements for bandwidth, delay, and jitter. For instance, bandwidth, delay, and jitter
