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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 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 5. ACL Resequencing
Rules Resequencing
Rules Before Resequencing: 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
Rules After Resequencing: 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 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.
● Resequence an IPv4 or MAC ACL.
EXEC mode
resequence access-list {ipv4 | mac} {access-list-name StartingSeqNum Step-to-Increment}
● Resequence an IPv4 prefix-list.
EXEC mode
resequence prefix-list {ipv4} {prefix-list-name StartingSeqNum Step-to-Increment}
The example shows the resequencing of an IPv4 access-list beginning with the number 2 and incrementing by 2.
Remarks and rules that originally have the same sequence number have the same sequence number after you apply the
resequence command.
Dell(config-ext-nacl)# show config
!
ip access-list extended test
remark 4 XYZ
remark 5 this remark corresponds to permit any host 1.1.1.1
seq 5 permit ip any host 1.1.1.1
remark 9 ABC
remark 10 this remark corresponds to permit ip any host 1.1.1.2
seq 10 permit ip any host 1.1.1.2
seq 15 permit ip any host 1.1.1.3
seq 20 permit ip any host 1.1.1.4
Dell# end
118
Access Control Lists (ACLs)