14 – VLAN Access List VACL 7,011 views

Posted by Mo7sin in CCNP, CCNP Switching (642 - 813) On 17/02/2012 at 12:53 AM

Understanding VACLs

These sections describe VACLs:

VACL Overview

Bridged Packets

Routed Packets

Multicast Packets

VACL Overview

VACLs can provide access control for all packets that are bridged within a VLAN or that are routed into or out of a VLAN or a WAN interface for VACL capture. Unlike regular Cisco IOS standard or extended ACLs that are configured on router interfaces only and are applied on routed packets only, VACLs apply to all packets and can be applied to any VLAN or WAN interface. VACLS are processed in hardware. VACLs use Cisco IOS ACLs. VACLs ignore any Cisco IOS ACL fields that are not supported in hardware.

You can configure VACLs for IP, IPX, and MAC-Layer traffic. VACLs applied to WAN interfaces support only IP traffic for VACL capture.

When you configure a VACL and apply it to a VLAN, all packets entering the VLAN are checked against this VACL. If you apply a VACL to the VLAN and an ACL to a routed interface in the VLAN, a packet coming in to the VLAN is first checked against the VACL and, if permitted, is then checked against the input ACL before it is handled by the routed interface. When the packet is routed to another VLAN, it is first checked against the output ACL applied to the routed interface and, if permitted, the VACL configured for the destination VLAN is applied. If a VACL is configured for a packet type and a packet of that type does not match the VACL, the default action is deny.

NoteTCP Intercepts and Reflexive ACLs take precedence over a VACL action if these are configured on the same interface.

VACLs and CBAC cannot be configured on the same interface.

IGMP packets are not checked against VACLs.

When VACL capture is configured with Policy Based Routing (PBR) on the same interface, do not select BDD as the ACL merge algorithm. We recommend using ODM, the default ACL merge algorithm for the Supervisor Engine 720.

Bridged Packets

Figure 35-1 shows a VACL applied on bridged packets

Figure 35-1 Applying VACLs on Bridged Packets


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