QoS Configuration
129
Chapter 20. QoS Configuration
20.1 Brief Introduction to QoS
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.
With the fast development of computer networks, more and more networks are connected
into Internet. Users hope to get better services, such as dedicated bandwidth, transfer delay,
jitter voice, image, important data which enrich network service resources and always face
network congestion. Internet users bring forward higher requirements for QoS. Ethernet
technology is the widest network technology in the world recently. Now, Ethernet becomes the
leading technology in every independent LAN, and many LAN in the form of Ethernet have
become a part of internet. With the development of Ethernet technology, Ethernet connecting
will become one of main connecting for internet users. To execute end-to-end QoS solution
has to consider the service guarantee of Ethernet QoS, which needs Ethernet device applies
to Ethernet technology to provide different levels of QoS guarantee for different types of
service flow, especially the service flow highly requiring delay and jitter.
20.1.1 Traffic
Traffic means all packets through switch.
20.1.2 Traffic Classification
Traffic classification is to identify packets conforming to certain characters according to
certain rules. It is the basis and prerequisite for proving differentiated services. A traffic
classification rule can use the precedence bits in the type of service (ToS) field of the IP
packet header to identify traffic with different precedence characteristics. A traffic
classification rule can also classify traffic according to the traffic classification policy set by the
network administrator, such as the combination of source address, destination address, MAC
address, IP protocol or the port numbers of the application. Traffic classification is generally
based on the information in the packet header and rarely based on the content of the packet.
Summary of Contents for S6424-S2C2 series
Page 1: ......
