Dell Force10 E600i FTOS Version 8.4.1.5 Configuration Guide for ExaScale - Page 805

Determine the order in which ACLs are used to classify traffic When you link class-maps to queues using the command service-queue, FTOS matches the class-maps according to queue priority (queue numbers closer to 0 have lower priorities). For example, in the example in Create a Layer 3 class map, class-map cmap2 is matched against ingress packets before cmap1. ACLs acl1 and acl2 have overlapping rules because the address range 20.1.1.0/24 is within 20.0.0.0/8. Therefore, (without the keyword order) packets within the range 20.1.1.0/24 match positive against cmap1 and are buffered in queue 7, though you intended for these packets to match positive against cmap2 and be buffered in queue 4. In cases such as these, where class-maps with overlapping ACL rules are applied to different queues, use the order keyword to specify the order in which you want to apply ACL rules, as shown in the example in Create a Layer 3 class map. The order can range from 0 to 254. FTOS writes to the CAM ACL rules with lower order numbers (order numbers closer to 0) before rules with higher order numbers so that packets are matched as you intended. By default, all ACL rules have an order of 254. Set DSCP values for egress packets based on flow Match-any Layer 3 flows may have several match criteria. All flows that match at least one of the match criteria are mapped to the same queue since they are in the same class map. Setting a DSCP value from QOS-POLICY-IN mode (refer to Set a DSCP value for egress packets) assigns the same DSCP value to all of the matching flows in the class-map. The Flow-based DSCP Marking feature allows you to assign different DSCP to each match criteria CLASS-MAP mode using the option set-ip-dscp with the match command so that matching flows within a class map can have different DSCP values, as shown in the example below. The values you set from CLASS-MAP mode override the value you QoS input policy DSCP value, and packets matching the rule are marked with the specified value. FTOS#show run class-map ! class-map match-any example-flowbased-dscp match ip access-group test set-ip-dscp 2 match ip access-group test1 set-ip-dscp 4 match ip precedence 7 set-ip-dscp 1 FTOS#show run qos-policy-input ! qos-policy-input flowbased set ip-dscp 3 FTOS# show cam layer3 linecard 2 port-set 0 Cam Port Dscp Proto Tcp Src Dst SrcIp DstIp DSCP Queue Index Flag Port Port Marking 16260 1 0 TCP 0x0 0 0 1.1.1.0/24 0.0.0.0/0 2 0 16261 1 0 UDP 0x0 0 0 2.2.2.2/32 0.0.0.0/0 4 0 16262 1 56 0 0x0 0 0 0.0.0.0/0 0.0.0.0/0 1 0 24451 1 0 0 0x0 0 0 0.0.0.0/0 0.0.0.0/0 - 0 Quality of Service | 805