14-5
Cisco 7600 Series Router Cisco IOS Software Configuration Guide—12.1E
78-14064-04
Chapter 14 Configuring IEEE 802.1Q Tunneling and Layer 2 Protocol Tunneling
Configuring 802.1Q Tunneling
• If the service provider does not want the customer to see its switches, CDP should be disabled on
the 802.1Q tunnel port as follows:
Router(config-if)# no cdp enable
Configuring 802.1Q Tunneling
These sections describe 802.1Q tunneling configuration:
• Preconfiguration Tasks, page 14-5
• Configuring 802.1Q Tunnel Ports, page 14-6
• Configuring the Cisco 7600 Series Router to Tag Native VLAN Traffic, page 14-6
Caution Ensure that only the appropriate tunnel ports are in any VLAN used for tunneling and that one VLAN is
used for each tunnel. Incorrect assignment of tunnel ports to VLANs can forward traffic inappropriately.
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.
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