Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.100.0 - Page 674

Use Step 1 or Step 2 to start creating a Layer 2 class map. 1 Create a match-any class map. CONFIGURATION mode class-map match-any 2 Create a match-all class map. CONFIGURATION mode class-map match-all 3 Specify your match criteria. CLASS MAP mode match mac After you create a class-map, Dell Networking OS places you in CLASS MAP mode. Match-any class maps allow up to five access-lists. Match-all class-maps allow only one. You can match against only one VLAN ID. 4 Link the class-map to a queue. POLICY MAP mode service-queue Determining the Order in Which ACLs are Used to Classify Traffic When you link class-maps to queues using the service-queue command, Dell Networking OS matches the class-maps according to queue priority (queue numbers closer to 0 have lower priorities). For example, as described in the previous example, 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 keyword order. Dell Networking OS 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. • Specify the order in which you want to apply ACL rules using the keyword order. order The order can range from 0 to 254. By default, all ACL rules have an order of 255. Displaying Configured Class Maps and Match Criteria To display all class-maps or a specific class map, use the following command. Dell Networking OS Behavior: An explicit "deny any" rule in a Layer 3 ACL used in a (match any or match all) class-map creates a "default to Queue 0" entry in the CAM, which causes unintended traffic classification. In the following example, traffic is classified in two Queues, 1 and 2. Class-map ClassAF1 is "match any," and ClassAF2 is "match all". • Display all class-maps or a specific class map. EXEC Privilege mode show qos class-map 674 Quality of Service (QoS)