White Papers

Table Of Contents
NOTE: CAM optimization applies only when you use an ACL VLAN group; it does not apply if you apply an ACL on individual
VLANs.
Guidelines for Configuring ACL VLAN Groups
Keep the following points in mind when you configure ACL VLAN groups:
The VLAN member interfaces, on which the ACL in an ACL VLAN group is applied, function as restricted interfaces. The ACL
VLAN group name identifies the group of VLANs on which hierarchical filtering is performed.
You can add only one ACL to an interface at a time.
When you apply an ACL VLAN group to a member interface, an error message is displayed if an ACL with different criteria
has already been separately applied to the interface.
The maximum number of members in an ACL VLAN group is determined by the type of switch and its hardware capabilities.
This scaling limit depends on the number of slices that are allocated for ACL CAM optimization. If one slice is allocated, the
maximum number of VLAN members is 256 for all ACL VLAN groups. If two slices are allocated, the maximum number of
VLAN members is 512 for all ACL VLAN groups.
The maximum number of VLAN groups that you can configure also depends on the hardware specifications of the switch.
Each VLAN group is mapped to a unique ID in the hardware. The maximum number of ACL VLAN groups supported is 31.
Only a maximum of two components (iSCSI counters, Open Flow, ACL optimization) can be allocated virtual flow processing
slices at a time.
Port ACL optimization is applicable only for ACLs that are applied without the VLAN range.
You cannot view the statistical details of ACL rules per VLAN and per interface if you enable the ACL VLAN group capability.
You can view the counters per ACL only by using the show ip accounting access list command.
On a port, you can apply Layer 2 ACLs on a VLAN or a set of VLANs. In this case, CAM optimization is not applied.
To enable optimization of CAM space for Layer 2 or Layer 3 ACLs that are applied to ports, the port number is removed as
a qualifier for ACL application on ports, and port bits are used. When you apply the same ACL to a set of ports, the port
bitmap is set when the ACL flow processor (FP) entry is added. When you remove the ACL from a port, the port bitmap is
removed.
If you do not attach an ACL to any of the ports, the FP entries are deleted. Similarly, when the same ACL is applied on a
set of ports, only one set of entries is installed in the FP, thereby effectively saving CAM space. The optimization is enabled
only if you specify the optimized option with the ip access-group command. This option is not valid for VLAN and LAG
interfaces.
Configuring an ACL VLAN Group
Configure an ACL VLAN group to optimize ACL CAM use.
NOTE:
After you configure an ACL VLAN group, you must allocate CAM memory for ACL VLAN services to enable CAM
optimization. See Allocating ACL VLAN CAM for more information.
1. Create an ACL VLAN group
CONFIGURATION mode
acl-vlan-group group-name
2. Add a description.
ACL-VLAN-GROUP CONFIGURATION (conf-acl-vl-grp) mode
description description
3. Apply an egress IP ACL.
ACL-VLAN-GROUP CONFIGURATION (conf-acl-vl-grp) mode
ip access-group access-list-name out implicit-permit
4. Specify the VLAN members in the ACL VLAN group.
ACL-VLAN-GROUP CONFIGURATION (conf-acl-vl-grp) mode
member vlan vlan-range
100
Access Control Lists (ACLs)