Operation Manual – QoS-QoS ProfileH3C S3100 Series Ethernet Switches Chapter 1 QoS Configuration1-1Chapter 1 QoS Configuration1.1 Overview1.1.1 Introduction to QoSQuality of Service (QoS) is a concept concerning service demand and supply. It reflectsthe ability to meet customer needs. Generally, QoS does not focus on grading servicesprecisely, but on improving services under certain conditions.In an internet, QoS refers to the ability of the network to forward packets. Theevaluation on QoS of a network can be based on different aspects because the networkmay provide various services. Generally, QoS refers to the ability to provide improvedservice by addressing the essential issues such as delay, jitter, and packet loss ratio inthe packet forwarding process.1.1.2 Traditional Packet Forwarding ServiceIn 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 packetforwarding is determined by the order in which packets arrive. All the packets share theresources of the network. Network resources available to the packets completelydepend on the time they arrive. This service policy is known as Best-effort, whichdelivers the packets to their destination with the best effort, with no assurance andguarantee for delivery delay, jitter, packet loss ratio, reliability, and so on.The traditional Best-Effort service policy is only suitable for applications insensitive tobandwidth and delay, such as WWW, file transfer and E-mail.1.1.3 New Applications and New RequirementsWith the expansion of computer network, more and more networks become part of theInternet. The Internet gains rapid development in terms of scale, coverage and userquantities. More and more users use the Internet as a platform for their services and fordata transmission.Besides the traditional applications such as WWW, E-mail, and FTP, new services aredeveloped on the Internet, such as tele-education, telemedicine, video telephone,videoconference and Video-on-Demand (VoD). Enterprise users expect to connecttheir 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 specialrequirements for bandwidth, delay, and jitter. For instance, bandwidth, delay, and jitter
