Dell Force10 S55T S55 Configuration Guide FTOS 8.3.5.3 - Page 575

By default, if no match occurs, the packet is queued to the default queue, Queue 0. In the following configuration, packets are classified to queues using the three class maps: ! policy-map-input input-policy service-queue 1 class-map qos-BE1 service-queue 3 class-map qos-AF3 service-queue 4 class-map qos-AF4 ! class-map match-any qos-AF3 match ip dscp 24 match ip access-group qos-AF3-ACL ! class-map match-any qos-AF4 match ip dscp 32 match ip access-group qos-AF4-ACL ! class-map match-all qos-BE1 match ip dscp 0 match ip access-group qos-BE1-ACL The packet classification logic for the above configuration is as follows: 1. Match packets against match-any qos-AF4. If a match exists, queue the packet as AF4 in Queue 4, and if no match exists, go to the next class map. 2. Match packets against match-any qos-AF3. If a match exists, queue the packet as AF3 in Queue 3, and if no match exists, go to the next class map. 3. Match packets against match-all qos-BE1. If a match exists, queue the packet as BE1, and if no match exists, queue the packets to the default queue, Queue 0. You can optionally classify packets using their DSCP marking, instead of placing packets in Queue 0, if no match occurs. In the above example, if no match occurs against match-all qos-BE1, the classification logic continues: 4. Queue the packet according to the DSCP marking. The DSCP to Queue mapping will be as per the Table 31-5. The behavior is similar for trust dot1p fallback in a Layer2 input policy map; the dot1p-to-queue mapping is according to Table 31-6. To enable Fall Back to trust diffserve or dot1p: Task Command Syntax Classify packets according to their DSCP value as a secondary option in case no match occurs against the configured class maps. trust {diffserve | dot1p} fallback Command Mode POLICY-MAP-IN Quality of Service | 575