Dell Force10 E1200i FTOS Version 8.4.1.5 Configuration Guide for ExaScale - Page 812

www.dell.com | support.dell.com Fall Back to trust diffserve or dot1p e Fall Back to trust diffserve or dot1p is available only on platforms: When using QoS service policies with multiple class maps, you can configure FTOS to use the incoming DSCP or dot1p marking as a secondary option for packet queuing in the event that no match occurs in the class maps. When class-maps are used, traffic is matched against each class-map sequentially from first to last. The sequence is based on the priority of the rules, as follows: 1. rules with lowest priority, or in the absence of a priority configuration, 2. rules of the next numerically higher queue 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 44-5, "Default DSCP to Queue Mapping," in Quality of Service. 812 | Quality of Service