Configuring Quality of Service 385The scheduling scheme is enabled system-wide. Queues assigned to the strict priority policy are automaticallyassigned to the highest priority queue By default all values are set as Strict Priority. When changing to WRRmode the default weight value is one. Queue weight values can be assigned in any order using WRR. WRR val-ues can be assigned system-wide. Best effort traffic is always assigned to the first queue. WRR values must beassigned so that Queue 1 remains best effort.Defining CoS Global ParametersClass of Service global parameters are set from the CoS Settings page.To open the CoS Settings page, click Quality of Service→ CoS Global Parameters → CoS Settings in thetree view.Figure 9-1. CoS Settings• Cos Mode — Enables or disables managing network traffic using Quality of Service.• Trust Mode — Determines which packet fields to use for classifying packets entering the device. Whenno rules are defined the traffic containing the predefined packet field (CoS or DSCP) is mapped accordingto the relevant trust modes table. Traffic not containing a predefined packet field is mapped to best effort.The possible Trust Mode field values are:– CoS (802.1P) — The output queue assignment is determined by the IEEE802.1p VLAN priority tag(VPT) or by the default VPT assigned to a port.– DSCP — The output queue assignment is determined by the DSCP field. interface Trust settingsoverrides the global Trust setting.Enabling Quality of Service:1 Open the CoS Settings page.2 Select Enable in the CoS Mode field.3 Click Apply Changes.Class of Service is enabled on the device.
