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Catalyst 3750 Metro Switch Command Reference
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Chapter 2 Catalyst 3750 Metro Switch Cisco IOS Commands
l2protocol-tunnel
You can enable point-to-point protocol tunneling individually for PAgP, LACP, UDLD, or for all three
protocols.
Loopback detection is not supported on Layer 2 protocol tunneling of PAgP, LACP, or UDLD packets.
Caution
PAgP, LACP, and UDLD protocol tunneling is only intended to emulate a point-to-point topology. An
erroneous configuration that sends tunneled packets to many ports could lead to a serious network
failure.
Dynamic Trunking Protocol (DTP) is not compatible with Layer 2 protocol tunneling because you must
manually configure asymmetric links with tunnel ports and trunk ports.
Edge switches on the outbound side of the service-provider network restore the proper Layer 2 protocol
and MAC address information and forward the packets to all tunnel, access, and Layer 2
protocol-enabled trunk ports in the same metro VLAN.
Enter the
shutdown-threshold
keyword to control the number of protocol packets per second that are
received on an interface before it shuts down. When no protocol option is specified with the keyword,
the threshold is applied to each of the tunneled Layer 2 protocol types. If you also set a drop threshold
on the interface, the shutdown-threshold value must be greater than or equal to the drop-threshold value.
When the shutdown threshold is reached, the interface is error-disabled. If you enabled error recovery
by entering the
errdisable recovery cause l2ptguard
global configuration command, the interface is
brought out of the error-disabled state and allowed to retry the operation when all the causes have timed
out. If the error recovery mechanism is not enabled for l2ptguard, the interface stays in the error-disabled
state until you enter the
shutdown
and
no shutdown
interface configuration commands.
Enter the
drop-threshold
keyword to control the number of protocol packets per second that are received
on an interface before it drops packets. When no protocol option is specified with a keyword, the
threshold is applied to each of the tunneled Layer 2 protocol types. If you also set a shutdown threshold
on the interface, the drop-threshold value must be less than or equal to the shutdown-threshold value.
When the drop threshold is reached, the interface drops Layer 2 protocol packets until the rate at which
they are received is below the drop threshold.
The configuration is saved in NVRAM.
Note
For more information about Layer 2 protocol tunneling, see the software configuration guide for this
release.
Examples
This example shows how to enable protocol tunneling for CDP packets and to configure the shutdown
threshold as 50 packets per second:
Switch(config-if)#
l2protocol-tunnel cdp
Switch(config-if)#
l2protocol-tunnel shutdown-threshold cdp 50
This example shows how to enable protocol tunneling for STP packets and to configure the drop
threshold as 400 packets per second:
Switch(config-if)#
l2protocol-tunnel stp
Switch(config-if)#
l2protocol-tunnel drop-threshold stp 400
This example shows how to enable point-to-point protocol tunneling for PAgP and UDLD packets and
to configure the PAgP drop threshold as 1000 packets per second:
Switch(config-if)#
l2protocol-tunnel point-to-point pagp
