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15-15
Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter 15 Configuring 802.1Q and Layer 2 Protocol Tunneling
Configuring Layer 2 Protocol Tunneling
Use the no switchport mode trunk, the no udld enable, and the no channel group
channel-group-number mode desirable interface configuration commands to return the interface to the
default settings.
For EtherChannels, you need to configure both the SP edge switches and the customer switches for
Layer 2 protocol tunneling. (See
This example shows how to configure the SP edge switch 1 and edge switch 2. VLANs 17, 18, 19, and
20 are the access VLANs, Fast Ethernet interfaces 0/1 and 0/2 are point-to-point tunnel ports with PAgP
and UDLD enabled, the drop threshold is 1000, and Fast Ethernet interface 0/3 is a trunk port.
SP edge switch 1 configuration:
Switch(config)# interface fastethernet0/1
Switch(config-if)# switchport access vlan 17
Switch(config-if)# switchport mode dot1q-tunnel
Switch(config-if)# l2protocol-tunnel point-to-point pagp
Switch(config-if)# l2protocol-tunnel point-to-point udld
Switch(config-if)# l2protocol-tunnel drop-threshold point-to-point pagp 1000
Switch(config-if)# exit
Switch(config)# interface fastethernet0/2
Switch(config-if)# switchport access vlan 18
Switch(config-if)# switchport mode dot1q-tunnel
Switch(config-if)# l2protocol-tunnel point-to-point pagp
Switch(config-if)# l2protocol-tunnel point-to-point udld
Switch(config-if)# l2protocol-tunnel drop-threshold point-to-point pagp 1000
Switch(config-if)# exit
Switch(config)# interface fastethernet0/3
Switch(config-if)# switchport trunk encapsulation isl
Switch(config-if)# switchport mode trunk
SP edge switch 2 configuration:
Switch(config)# interface fastethernet0/1
Switch(config-if)# switchport access vlan 19
Switch(config-if)# switchport mode dot1q-tunnel
Switch(config-if)# l2protocol-tunnel point-to-point pagp
Switch(config-if)# l2protocol-tunnel point-to-point udld
Switch(config-if)# l2protocol-tunnel drop-threshold point-to-point pagp 1000
Switch(config-if)# exit
Step 6
channel-group channel-group-number
mode desirable
Assign the interface to a channel group, and specify desirable for the PAgP
mode. For more information about configuring EtherChannels, see
Chapter 30, “Configuring EtherChannels.”
Step 7
exit
Return to global configuration mode.
Step 8
interface port-channel port-channel
number
Enter port-channel interface mode.
Step 9
shutdown
Shut down the interface.
Step 10
no shutdown
Enable the interface.
Step 11
end
Return to privileged EXEC mode.
Step 12
show l2protocol
Display the Layer 2 tunnel ports on the switch, including the protocols
configured, the thresholds, and the counters.
Step 13
copy running-config startup-config
(Optional) Save your entries in the configuration file.
Command
Purpose