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Catalyst 6500 Series Switch Cisco IOS Software Configuration Guide—Release 12.1 E
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Chapter 14 Configuring IEEE 802.1Q Tunneling and Layer 2 Protocol Tunneling
Configuring 802.1Q Tunneling
Preconfiguration Tasks
Before you can configure Layer 2 protocol tunneling, you must perform these tasks:
Step 1 On all the service provider edge switches, PortFast BPDU filtering must be enabled on the 802.1Q tunnel
ports as follows:
Router(config-if)# spanning-tree bpdufilter enable
Router(config-if)# spanning-tree portfast
Note With Release 12.1(13)E and later releases, PortFast BPDU filtering is enabled automatically
on tunnel ports. With releases earlier than Release 12.1(13)E, you must manually enable
PortFast BPDU filtering on tunnel ports.
Step 2 At least one VLAN must be available for Native VLAN tagging (vlan dot1q tag native option). If you
use all the available VLANs and then try to enable the vlan dot1q tag native option, the option will not
be enabled.
Step 3 On all the service provider core switches, tag native VLAN egress traffic and drop untagged native
VLAN ingress traffic by entering the following command:
Router(config)# vlan dot1q tag native
Step 4 On all the customer switches, either enable or disable the global vlan dot1q tag native option.
Note If this option is enabled on one switch and disabled on another switch, all traffic is dropped;
all customer switches must have this option configured the same on each switch.
Configuring 802.1Q Tunnel Ports
To configure 802.1Q tunneling on a port, perform this task:
Command Purpose
Step 1 Router(config)# interface type1 slot/port Selects the LAN port to configure.
Step 2 Router(config-if)# switchport Configures the LAN port for Layer 2 switching:
You must enter the switchport command once
without any keywords to configure the LAN port as a
Layer 2 interface before you can enter additional
switchport commands with keywords.
Required only if you have not entered the switchport
command already for the interface.
Step 3 Router(config-if)# switchport mode dot1qtunnel Configures the Layer 2 port as a tunnel port.
Router(config-if)# no switchport mode dot1qtunnel Clears the tunnel port configuration.