Operation Manual – QoSH3C S7500 Series Ethernet Switches Chapter 1 QoS Configuration1-61.1.6 Packet FilteringPacket filter means filtering the service traffic. For example, in the operation of droppingpackets, the service traffic matching the traffic classification rule is dropped and theother traffic is permitted. Ethernet switches adopt complicated traffic classification rulesto filter the packets based on much information and to drop these useless, unreliable,and doubtful packets. Therefore, the network security is enhanced.The two critical steps in the packet filtering operation are:Step1: Classify the inbound packets of the port by the specific classification rules.Step 2: Filter and drop the classified packets.The packet filtering feature can be implemented by applying ACL rules to a port. Referto the description in the ACL module for detailed configurations.1.1.7 Rate Limiting on PortsRate limiting on ports is port-based rate limiting. It limits the total rate of outboundpackets on a port.1.1.8 TPThe network will be made more congested by plenty of continuous burst packets if thetraffic of each user is not limited. The traffic of each user must be limited in order tomake better use of the limited network resources and provide better service for moreusers. For example, if each traffic can only get its committed resources in an interval,network congestion caused by excess bursts can be avoided.Traffic policing (TP) is a kind of traffic control policy to limit the traffic and its resourceusage by supervising the traffic specification. The traffic control policy is implementedaccording to the evaluation results on the premise of knowing whether the trafficexceeds the specification. The token bucket is generally adopted in the evaluation oftraffic specification.I. Traffic evaluation and the token bucketThe token bucket can be considered as a container with a certain capacity to holdtokens. The system puts tokens into the bucket at the set rate. When the token bucketis full, the extra tokens will overflow and the number of tokens in the bucket stopsincreasing.
