access-list template
To enable template access control list (ACL) processing (as defined by the Template ACL feature), use the access-list template command in global configuration mode. To disable template ACL processing, use the no form of this command.
access-list template [number-of-rules]
no access-list template [number-of-rules]
Syntax Description
number-of-rules |
(Optional) Specifies the maximum number of rules that an ACL may have in order to be considered for template status, that is, considered as a template ACL. Only ACLs whose number of rules is the same as or smaller than those specified in the number-of-rules argument will be considered for template status. If the number-of-rules argument is omitted, the default of 100 will be used, and only ACLs with 100 or fewer rules will be considered for template status. The range for the number-of-rules argument is from 1 to 100. |
Command Default
Template ACL processing is enabled.
Command Modes
Global configuration (config)
Command History
Release |
Modification |
---|---|
12.2(27)SBKA |
This command was introduced on the Cisco 10000 series router. |
Cisco IOS XE Release 2.4 |
This command was implemented on the Cisco ASR 1000 series routers. |
Usage Guidelines
Reducing the number of rules for template ACL status can lower CPU utilization. Checking each ACL against other known ACLs in the system is easier if the matching task can be terminated earlier.
Note |
Changes in CPU utilization occur only during session initialization. Steady-state CPU utilization is unaffected by these changes in ACL processing. |
If template ACL processing is disabled, the system replaces all existing template ACL instances with ACLs. Therefore, before you disable the feature, you must ensure that the number of template ACLs does not exceed the system capabilities.
If template ACL processing is enabled, the system scans and evaluates all configured per-session ACLs, and then creates all required template ACLs.
Default Settings
If the number-of-rules argument is specified for the no version of the command, the default of 100 will be used, and only ACLs with 100 or fewer rules will be considered for template status.
Cisco 1000 Series Routers
On the Cisco 1000 series routers, if the number of rules is smaller than the largest similar Attribute 242 ACL, the processing of this new setting can use up substantial CPU resources because ACLs that previously would be considered as template ACL duplicates are instead compiled using TurboACL compilation without regard to other ACLs already in the router. If the ACLs have fewer than eight rules, the CPU increase will not be so noticeable, because ACLs will be compiled as MiniACLs.
If the number of rules is set larger than the largest similar Attribute 242 ACL, then increased CPU resources may be required to conduct the comparison task. This potential increase in CPU resources is offset by the elimination of TurboACL and MiniACL compilation.
Examples
The following example specifies that ACLs with 50 or fewer rules will be considered for template ACL status:
Router(config)# access-list template 50