Dell Force10 S4820T S4820T Configuration Guide - Page 771

Specify a WRED profile to yellow and/or green traffic using the command wred from QOS-POLICY-OUT mode. See Apply a WRED profile to traffic. Create Policy Maps There are two types of policy maps: input and output. Create Input Policy Maps There are two types of input policy-maps: Layer 3 and Layer 2. 1. Create a Layer 3 input policy map using the command policy-map-input from CONFIGURATION mode. Create a Layer 2 input policy map by specifying the keyword layer2 with the policy-map-input command. 2. Once you create an input policy map, do one or more of the following: • Apply a class-map or input QoS policy to a queue • Apply an input QoS policy to an input policy map • Honor DSCP values on ingress packets • Honoring dot1p values on ingress packets 3. Apply the input policy map to an interface. FTOS Behavior: On ExaScale, FTOS cannot classify protocol traffic on a Layer 2 interface using Layer 3 policy map. The packets always take the default queue, Queue 0, and cannot be rate-policed. Apply a class-map or input QoS policy to a queue Assign an input QoS policy to a queue using the command service-queue from POLICY-MAP-IN mode. Apply an input QoS policy to an input policy map Apply an input QoS policy to an input policy map using the command policy-aggregate from POLICY-MAP-IN mode. Honor DSCP values on ingress packets FTOS provides the ability to honor DSCP values on ingress packets using Trust DSCP feature. Enable this feature using the command trust diffserv from POLICY-MAP-IN mode. Table 38-5 lists the standard DSCP definitions, and indicates to which queues FTOS maps DSCP values. When Trust DSCP is configured the matched packets and matched bytes counters are not incremented in show qos statistics. Quality of Service (QoS) | 771