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Catalyst 3750 SwitchSoftware Configuration Guide
OL-8550-09
Chapter17 Configuring IEEE 802.1Q and Layer 2 Protocol Tunneling
Configuring Layer 2 Protocol Tunneling
Configuring the Customer Switch
After configuring the SP edge switch, begin in privileged EXEC mode and follow these steps to
configure a customer switch for Layer2 protocol tunneling for EtherChannels:
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 Figure1 7-6 on page 17-10.)
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 1 and 2 are point-to-point tunnel ports with PAgP and
UDLD enabled, the drop threshold is 1000, and Fast Ethernet interface 3 is a trunk port.
SP edge switch 1 configuration:
Switch(config)# interface fastethernet1/0/1
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 fastethernet1/0/2
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
Command Purpose
Step1 configure terminal Enter global configuration mode.
Step2 interface interface-id Enter the interface configuration mode. This should be the customer switch
port.
Step3 switchport trunk encapsulation
dot1q
Set the trunking encapsulation format to IEEE 802.1Q.
Step4 switchport mode trunk Enable trunking on the interface.
Step5 udld enable Enable UDLD in normal mode on the interface.
Step6 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 36, “Configuring EtherChannels and Link-State Tracking.”
Step7 exit Return to global configuration mode.
Step8 interface port-channel port-channel
number
Enter port-channel interface mode.
Step9 shutdown Shut down the interface.
Step10 no shutdown Enable the interface.
Step11 end Return to privileged EXEC mode.
Step12 show l2protocol Display the Layer 2 tunnel ports on the switch, including the protocols
configured, the thresholds, and the counters.
Step13 copy running-config startup-config (Optional) Save your entries in the configuration file.