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Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
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Chapter 28 Configuring Network Security with ACLs
Configuring VLAN Maps
VLAN Map Configuration Guidelines
Follow these guidelines when configuring VLAN maps:
• If there is no ACL configured to deny traffic on an interface and no VLAN map is configured, all
traffic is permitted.
• Each VLAN map consists of a series of entries. The order of entries in an VLAN map is important.
A packet that comes into the switch is tested against the first entry in the VLAN map. If it matches,
the action specified for that part of the VLAN map is taken. If there is no match, the packet is tested
against the next entry in the map.
• If the VLAN map has at least one match clause for the type of packet (IP or MAC) and the packet
does not match any of these match clauses, the default is to drop the packet. If there is no match
clause for that type of packet in the VLAN map, the default is to forward the packet.
• The system might take longer to boot if you have configured a very large number of ACLs.
• Logging is not supported for VLAN maps.
• If VLAN map configuration cannot be applied in hardware, all packets in that VLAN must be routed
by software.
• When a switch has an IP access list or MAC access list applied to a Layer 2 interface, and you apply
a VLAN map to a VLAN that the port belongs to, the port ACL takes precedence over the VLAN
map.
• You can configure VLAN maps on primary and secondary VLANs. However, we recommend that
you configure the same VLAN maps on private-VLAN primary and secondary VLANs.
• When a frame is Layer-2 forwarded within a private VLAN, the same VLAN map is applied at the
ingress side and at the egress side. When a frame is routed from inside a private VLAN to an external
port, the private-VLAN map is applied at the ingress side.
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For frames going upstream from a host port to a promiscuous port, the VLAN map configured
on the secondary VLAN is applied.
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For frames going downstream from a promiscuous port to a host port, the VLAN map
configured on the primary VLAN is applied.
To filter out specific IP traffic for a private VLAN, you should apply the VLAN map to both the
primary and secondary VLANs. For more information about private VLANs, see Chapter 12,
“Configuring Private VLANs.”
• See the “Using VLAN Maps in Your Network” section on page 28-34 for configuration examples.
• For information about using both router ACLs and VLAN maps, see the “VLAN Maps and Router
ACL Configuration Guidelines” section on page 28-36.