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Software Configuration Guide—Release 12.2(25)SG
OL-7659-03
Chapter 18 Configuring 802.1Q and Layer 2 Protocol Tunneling
Configuring Layer 2 Protocol Tunneling
Use the no l2protocol-tunnel [cdp | stp | vtp] interface configuration command to disable protocol
tunneling for one of the Layer 2 protocols or for all three. Use the no l2protocol-tunnel
shutdown-threshold [cdp | stp | vtp] and the no l2protocol-tunnel drop-threshold [cdp | stp | vtp]
commands to return the shutdown and drop thresholds to the default settings.
This example shows how to configure Layer 2 protocol tunneling for CDP, STP, and VTP and how to
verify the configuration.
Switch(config)# interface FastEthernet2/1
Switch(config-if)# l2protocol-tunnel cdp
Switch(config-if)# l2protocol-tunnel stp
Switch(config-if)# l2protocol-tunnel vtp
Step 3
Switch(config-if)# switchport
mode access
or
switchport mode dot1q-tunnel
Configures the interface as an access port or as an 802.1Q tunnel port.
Step 4
Switch(config-if)#
l2protocol-tunnel [cdp | stp |
vtp]
Enables protocol tunneling for the desired protocol. If no keyword is
entered, tunneling is enabled for all three Layer 2 protocols.
Step 5
Switch(config-if)#
l2protocol-tunnel
shutdown-threshold [cdp | stp |
vtp]
value
(Optional) Configures the threshold for packets-per-second accepted for
encapsulation. The interface is disabled if the configured threshold is
exceeded. If no protocol option is specified, the threshold applies to each of
the tunneled Layer 2 protocol types. The range is 1 to 4096. The default is
to have no threshold configured.
Note If you also set a drop threshold on this interface, the
shutdown-threshold value must be greater than or equal to the
drop-threshold value.
Step 6
Switch(config-if)#
l2protocol-tunnel drop-threshold
[cdp | stp | vtp]
value
(Optional) Configures the threshold for packets-per-second accepted for
encapsulation. The interface drops packets if the configured threshold is
exceeded. If no protocol option is specified, the threshold applies to each of
the tunneled Layer 2 protocol types. The range is 1 to 4096. The default is
to have no threshold configured.
Note If you also set a shutdown threshold on this interface, the
drop-threshold value must be less than or equal to the
shutdown-threshold value.
Step 7
Switch(config-if)# exit
Returns to global configuration mode.
Step 8
Switch(config)# errdisable
recovery cause l2ptguard
(Optional) Configures the recovery mechanism from a Layer 2
maximum-rate error so that the interface is re-enabled and can try again.
Errdisable recovery is disabled by default; when enabled, the default time
interval is 300 seconds.
Step 9
Switch(config)# l2protocol-tunnel
cos
value
(Optional) Configures the CoS value for all tunneled Layer 2 PDUs. The
range is 0 to 7; the default is the default CoS value for the interface. If none
is configured, the default is 5.
Step 10
Switch(config)# end
Returns to privileged EXEC mode.
Step 11
Switch# show l2protocol
Displays the Layer 2 tunnel ports on the switch, including the protocols
configured, the thresholds, and the counters.
Step 12
Switch# copy running-config
startup-config
(Optional) Saves your entries in the configuration file.
Command Purpose