Dell Force10 C150 FTOS Configuration Guide FTOS 8.4.2.7 E-Series TeraScale, C- - Page 138

www.dell.com | support.dell.com Standard and Extended ACLs take up the same amount of CAM space. A single ACL rule uses 2 CAM entries whether it is identified as a Standard or Extended ACL. 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 Figure 8-2, 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 Figure 8-2. 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. Figure 8-2. Using the Order Keyword in ACLs FTOS(conf)#ip access-list standard acl1 FTOS(config-std-nacl)#permit 20.0.0.0/8 FTOS(config-std-nacl)#exit FTOS(conf)#ip access-list standard acl2 FTOS(config-std-nacl)#permit 20.1.1.0/24 order 0 FTOS(config-std-nacl)#exit FTOS(conf)#class-map match-all cmap1 FTOS(conf-class-map)#match ip access-group acl1 FTOS(conf-class-map)#exit FTOS(conf)#class-map match-all cmap2 FTOS(conf-class-map)#match ip access-group acl2 FTOS(conf-class-map)#exit FTOS(conf)#policy-map-input pmap FTOS(conf-policy-map-in)#service-queue 7 class-map cmap1 FTOS(conf-policy-map-in)#service-queue 4 class-map cmap2 FTOS(conf-policy-map-in)#exit FTOS(conf)#interface gig 1/0 FTOS(conf-if-gi-1/0)#service-policy input pmap IP Fragment Handling FTOS supports a configurable option to explicitly deny IP fragmented packets, particularly second and subsequent packets. It extends the existing ACL command syntax with the fragments keyword for all Layer 3 rules applicable to all Layer protocols (permit/deny ip/tcp/udp/icmp). • Both standard and extended ACLs support IP fragments. 138 | IP Access Control Lists (ACL), Prefix Lists, and Route-maps