Core issue
A VLAN Access Control List (VACL) is an Access Control List (ACL) for a switch VLAN. The pre-block VACLs are permits at the top of the VACL, and the post-block VACLs are entries that belong at the bottom of the VACL.
The sensor dynamically creates a VACL and applies it to certain VLANS (of your choice) on the switch. It then includes the VACLs that you have manually created. The pre-block is first, followed by the dynamic entries and then the post-block.
Resolution
A sample configuration of a VACL would look like this:
Console> (enable)set security acl ip < postacl > permit arp
Console> (enable)set security acl ip < postacl > permit ip any any
Determine the network's pre-shun and post-shun traffic, and customize it to suit configuration requirements.
Once the VACLs are defined on the switch, you can define the blocking device on Intrusion Detection System (IDS), and include the names for post-block and pre-block VACLs.
For more information on configuration with IDS device manager , refer to the Configuring Catalyst 6K Blocking Device Interfaces section of IDS Device Manager Configuration Tasks.
