Dell PowerSwitch S4820T Configuration Guide for the S4820T System 9.14.1.0 - Page 131

ACL Resequencing ACL resequencing allows you to re-number the rules and remarks in an access or prefix list. The placement of rules within the list is critical because packets are matched against rules in sequential order. To order new rules using the current numbering scheme, use resequencing whenever there is no opportunity. For example, the following table contains some rules that are numbered in increments of 1. You cannot place new rules between these packets, so apply resequencing to create numbering space, as shown in the second table. In the same example, apply resequencing if more than two rules must be placed between rules 7 and 10. You can resequence IPv4 and IPv6 ACLs, prefixes, and MAC ACLs. No CAM writes happen as a result of resequencing, so there is no packet loss; the behavior is similar Hot-lock ACLs. NOTE: ACL resequencing does not affect the rules, remarks, or order in which they are applied. Resequencing merely renumbers the rules so that you can place new rules within the list as needed. Table 7. ACL Resequencing Rules Rules Before Resequencing: Rules After Resequencing: Resquencing seq 5 permit any host 1.1.1.1 seq 6 permit any host 1.1.1.2 seq 7 permit any host 1.1.1.3 seq 10 permit any host 1.1.1.4 seq 5 permit any host 1.1.1.1 seq 10 permit any host 1.1.1.2 seq 15 permit any host 1.1.1.3 seq 20 permit any host 1.1.1.4 Resequencing an ACL or Prefix List Resequencing is available for IPv4 and IPv6 ACLs, prefix lists, and MAC ACLs. To resequence an ACL or prefix list, use the following commands. You must specify the list name, starting number, and increment when using these commands. • IPv4, IPv6, or MAC ACL EXEC mode resequence access-list {ipv4 | ipv6 | mac} {access-list-name StartingSeqNum Step-to-Increment} • IPv4 or IPv6 prefix-list EXEC mode resequence prefix-list {ipv4 | ipv6} {prefix-list-name StartingSeqNum Step-to-Increment} Examples of Resequencing ACLs When Remarks and Rules Have the Same Number or Different Numbers Remarks and rules that originally have the same sequence number have the same sequence number after you apply the resequence command. The example shows the resequencing of an IPv4 access-list beginning with the number 2 and incrementing by 2. DellEMC(config-ext-nacl)# show config ! Access Control Lists (ACLs) 131