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Software Configuration Guide—Release 15.0(2)SG
OL-23818-01
Chapter 25 Configuring 802.1Q Tunneling, VLAN Mapping, and Layer 2 Protocol Tunneling
Configuring 802.1Q Tunneling
EtherChannel port groups are compatible with tunnel ports as long as the 802.1Q configuration is
consistent within an EtherChannel port group.
Port Aggregation Protocol (PAgP), Link Aggregation Control Protocol (LACP), and UniDirectional
Link Detection (UDLD) are supported on 802.1Q tunnel ports.
Dynamic Trunking Protocol (DTP) is not compatible with 802.1Q tunneling because you must
manually configure asymmetric links with tunnel ports and trunk ports.
Loopback detection is supported on 802.1Q tunnel ports.
When a port is configured as an 802.1Q tunnel port, spanning-tree bridge protocol data unit (BPDU)
filtering is automatically enabled on the interface. Cisco Discovery Protocol (CDP) is automatically
disabled on the interface.
Configuring an 802.1Q Tunneling Port
To configure a port as an 802.1Q tunnel port, perform this task:
Use the no vlan dot1q tag native global command and the no switchport mode dot1q-tunnel interface
configuration command to return the port to the default state of dynamic auto. Use the no vlan dot1q
tag native global configuration command to disable tagging of native VLAN packets.
This example shows how to configure an interface as a tunnel port, enable tagging of native VLAN
packets, and verify the configuration. In this configuration, the VLAN ID for the customer connected to
Gigabit Ethernet interface 2/7 is VLAN 22.
Switch(config)# interface gigabitethernet2/7
Switch(config-if)# switchport access vlan 22
% Access VLAN does not exist. Creating vlan 22
Switch(config-if)# switchport mode dot1q-tunnel
Command Purpose
Step 1 Switch# configure terminal Enters global configuration mode.
Step 2 Switch(config)# interface
interface-id Enters interface configuration mode and the interface to be configured as
a tunnel port. This should be the edge port in the service provider network
that connects to the customer switch. Valid interfaces include physical
interfaces and port-channel logical interfaces (port channels 1 to 64).
Step 3 Switch(config-if)# switchport
access vlan vlan-id Specifies the default VLAN, which is used if the interface stops trunking.
This VLAN ID is specific to the particular customer.
Step 4 Switch(config-if)# switchport mode
dot1q-tunnel Sets the interface as an 802.1Q tunnel port.
Step 5 Switch(config-if)# exit Returns to global configuration mode.
Step 6 Switch(config)# vlan dot1q tag
native (Optional) Sets the switch to enable tagging of native VLAN packets on
all 802.1Q trunk ports. When not set, and a customer VLAN ID is the
same as the native VLAN, the trunk port does not apply a metro tag, and
packets could be sent to the wrong destination.
Step 7 Switch(config)# end Returns to privileged EXEC mode.
Step 8 Switch# show dot1q-tunnel Displays the tunnel ports on the switch.
Step 9 Switch# show vlan dot1q tag native Displays 802.1Q native-VLAN tagging status.
Step 10 Switch# copy running-config
startup-config (Optional) Saves your entries in the configuration file.