Service Manual

Access Control List (ACL) VLAN Groups

and Content Addressable Memory (CAM)

This chapter describes the access control list (ACL) virtual local area network (VLAN) group and content

addressable memory (CAM) enhancements.

Optimizing CAM Utilization During the Attachment of

ACLs to VLANs

To minimize the number of entries in CAM, enable and configure the ACL CAM feature. Use this feature

when you apply ACLs to a VLAN (or a set of VLANs) and when you apply ACLs to a set of ports. The ACL

CAM feature allows you to effectively use the Layer 3 CAM space with VLANs and Layer 2 and Layer 3

CAM space with ports.

To avoid using too much CAM space, configure ACL VLAN groups into a single group. A class identifier

(Class ID) is assigned for each of the ACLs attached to the VLAN and this Class ID is used as an identifier

or locator in the CAM space instead of the VLAN ID. This method of processing reduces the number of

entries in the CAM area and saves memory space by using the Class ID for filtering in CAM instead of the

VLAN ID.

When you apply an ACL separately on the VLAN interface, each ACL has a mapping with the VLAN and

you use more CAM space. To maximize CAM space, create an ACL VLAN group and attach the ACL with

the VLAN members.

The ACL manager application on the router processor (RP1) contains all the state information about all

the ACL VLAN groups that are present. The ACL handler on the control processor (CP) and the ACL agent

on the line cards do not contain any information about the group. After you enter the acl-vlan-group

command, the ACL manager application performs the validation. If the command is valid, it is processed

and sent to the agent, if required. If a configuration error is found or if the maximum limit has exceeded

for the ACL VLAN groups present on the system, an error message displays. After you enter the acl-

vlan-group command, the ACL manager application verifies the following parameters:

• Whether the CAM profile is set in virtual flow processing (VFP).

• Whether the maximum number of groups in the system is exceeded.

• Whether the maximum number of VLAN numbers permitted per ACL group is exceeded.

• When a VLAN member that is being added is already a part of another ACL group.

After these verification steps are performed, the ACL manager considers the command valid and sends

the information to the ACL agent on the line card. The ACL manager notifies the ACL agent in the

following cases:

• A VLAN member is added or removed from a group and previously associated VLANs exist in the

group.

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