Configuring Quality of Service 441Configuring Quality of ServiceThis section provides information for defining and configuring Quality of Service (QoS) parameters.To open the Quality of Service page, click Quality of Service in the tree view.This section contians the following topics:• "Quality of Service (QoS) Overview" on page 441• "Configuring QoS Global Settings" on page 443Quality of Service (QoS) OverviewQuality of Service (QoS) provides the ability to implement QoS and priority queuing within a network.An implementation example that requires QoS includes certain types of traffic such as Voice, Videoand real-time traffic, which can be assigned a high priority queue, while other traffic can be assigneda lower priority queue. The result is an improved traffic flow for traffic with high demand.QoS is defined by:• Classification — Specifies which packet fields are matched to specific values. All packetsmatching the user-defined specifications are classified together.• Action — Defines traffic management where packets being forwarded are based on packetinformation, and packet field values such as VLAN priority tag (VPT) and DSCP (DiffServCode Point).VPT Classification InformationVLAN Priority Tags are used to classify the packets by mapping packets to one of the egress queues.VLAN Priority Tag to queue assignments are user-definable. The table below details the VPT toqueue default settings:Table 9-1. CoS to Queue Mapping Table Default valuesCoS Value Forwarding Queue Values0 q21 q1 (Lowest Priority)2 q1 (Lowest Priority)3 q24 q3
