Configuring An 802.1Q Tunneling Port - Cisco Catalyst 3550 series Software Configuration Manual

Configuring 802.1Q Tunneling
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Configuring an 802.1Q Tunneling Port

Beginning in privileged EXEC mode, follow these steps to configure a port as an 802.1Q tunnel port:
Command
Step 1 configure terminal
Step 2 interface interface-id
Step 3 switchport access vlan vlan-id
Step 4 switchport mode dot1q-tunnel
Step 5
exit
Step 6 vlan dot1q tag native
Step 7
end
Step 8 show dot1q-tunnel
Step 9
show vlan dot1q tag native
Step 10
copy running-config startup-config
Use the no switchport mode dot1q-tunnel interface configuration command to return the port to the
default state of dynamic desirable. Use the no vlan dot1q tag native global configuration command to
disable tagging of native VLAN packets.
Catalyst 3550 Multilayer Switch Software Configuration Guide
15-6
Fallback bridging is not supported on tunnel ports. Because all 802.1Q-tagged packets received from
a tunnel port are treated as non-IP packets, if fallback bridging is enabled on VLANs that have
tunnel ports configured, IP packets would be improperly bridged across VLANs. Therefore, you
must not enable fallback bridging on VLANs with tunnel ports.
Tunnel ports do not support IP access control lists (ACLs).
Layer 3 quality of service (QoS) ACLs and other QoS features related to Layer 3 information are
not supported on tunnel ports. MAC-based QoS is supported on tunnel ports.
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.
Purpose
Enter global configuration mode.
Enter interface configuration mode and the interface to be configured as
a tunnel port. This should be the edge port in the SP network that connects
to the customer switch. Valid interfaces include physical interfaces and
port-channel logical interfaces (port channels 1 to 64).
Specify the default VLAN, which is used if the interface stops trunking.
This VLAN ID is specific to the particular customer.
Set the interface as an 802.1Q tunnel port.
Return to global configuration mode.
(Optional) Set 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.
Return to privileged EXEC mode.
Display the tunnel ports on the switch.
Display 802.1Q native-VLAN tagging status.
(Optional) Save your entries in the configuration file.
Chapter 15 Configuring 802.1Q and Layer 2 Protocol Tunneling
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