H3C S9500 Series Operation Manual

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Contents

Operation Manual – QoS/ACLH3C S9500 Series Routing Switches Chapter 2 QoS Configuration2-1Chapter 2 QoS Configuration2.1 QoS OverviewConventional packet network treats all packets equally. Each switch/router processesall packets in First-in-First-out (FIFO) mode and then transfers them to the destinationin the best effort, but it provides no commitment and guarantee to such transmissionperformance as delay and jitter.With fast growth of computer networks, more and more data like voice and video thatare sensitive to bandwidth, delay and jitter are transmitted over the network. Thismakes growing demands on quality of service (QoS) of networks.Ethernet technology is a widely-used network technology dominant for independentLANs and many LANs based on Ethernet are organic parts of the Internet. In addition,Ethernet access is becoming one of the major access modes for Internet users.Therefore it is inevitable to consider Ethernet QoS if we want to achieve point-to-pointglobal QoS solution. Ethernet switching devices then naturally need to provide differentQoS guarantee for different types of services, especially for those which are sensitiveto delay and jitter.The following terms are involved in QoS.I. FlowIt refers to all packets passing thought the switch.II. Traffic classificationTraffic classification is the technology that identifies the packets with a specifiedattribute according to a specific rule. Classification rule refers to a packet filtering ruleconfigured by an administrator. A classification rule can be very simple. For example,the switch can identify the packets of different priority levels according to the ToS (typeof service) field in the packet headers. It can also be very complex. For example, it maycontain information of the link layer (layer 2), network layer (layer 3) and transport layer(layer 4) and the switch classifies packets according to such information as MACaddress, IP protocol, source address, destination address and port ID. Classificationrule often is limited to the information encapsulated at the packet header, rarely usingpacket contents.III. Packet filteringPacket filtering refers to filtering operation applied to traffic flow. For example, the denyoperation drops the traffic flow which matches the classification rule and allows other