Reference Guide

Access Control Lists (ACLs) | 111
Figure 6-18. Command Example: show config in ROUTER OSPF Mode
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.
Use Resequencing whenever there is no longer an opportunity to order new rules as desired using current
numbering scheme.
For example, Table 6-3 contains some rules that are numbered in increments of 1. No new rules can be
placed between these, so apply resequencing to create numbering space, as shown in Table 6-4. In the same
example, apply resequencing if more than two rules must be placed between rules 7 and 10.
IPv4 and IPv6 ACLs and prefixes and MAC ACLs can be resequenced. No CAM writes happen as a result
of resequencing, so there is no packet loss; the behavior is like Hot-lock ACLs.
Note: ACL Resequencing does not affect the rules or remarks or the order in which they are applied. It
merely renumbers them so that new rules can be placed within the list as desired.
Table 6-3. ACL Resequencing Example (Insert New Rules)
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
Table 6-4. ACL Resequencing Example (Resequenced)
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
FTOS(conf-router_ospf)#show config
!
router ospf 34
network 10.2.1.1 255.255.255.255 area 0.0.0.1
distribute-list prefix awe in
FTOS(conf-router_ospf)#