Cisco ME 3400 Command Reference Manual page 257

Chapter 2 Cisco ME 3400 Ethernet Access Switch Cisco IOS Commands
Command Modes Interface configuration
Command History Release
12.2(25)EX
Usage Guidelines You must enter this command, with or without protocol types, to tunnel Layer 2 packets.
If you enter this command for a port channel, all ports in the channel must have the same configuration.
Layer 2 protocol tunneling across a service-provider network ensures that Layer 2 information is
propagated across the network to all customer locations. When protocol tunneling is enabled, protocol
packets are encapsulated with a well-known Cisco multicast address for transmission across the network.
When the packets reach their destination, the well-known MAC address is replaced by the Layer 2
protocol MAC address.
You can enable Layer 2 protocol tunneling for CDP, STP, and VTP individually or for all three protocols.
The switch does not support VTP. CDP and STP are enabled by default network node interfaces (NNIs)
Note
and disabled by default but can be enabled on enhanced network interfaces (ENIs). User network
interfaces (UNIs) do not support any of these protocols.
In a service-provider network, you can use Layer 2 protocol tunneling to enhance the creation of
EtherChannels by emulating a point-to-point network topology. When protocol tunneling is enabled on
the service-provider switch for PAgP or LACP, remote customer switches receive the protocol data units
(PDUs) and can negotiate automatic creation of EtherChannels.
Only NNIs and ENIs support PAgP and LACP.
Note
To enable tunneling of PAgP, LACP, and UDLD packets, you must have a point-to-point network
topology. To decrease the link-down detection time, you should also enable UDLD on the interface when
you enable tunneling of PAgP or LACP packets.
You can enable point-to-point protocol tunneling for PAgP, LACP, and UDLD individually or for all
three protocols.
PAgP, LACP, and UDLD tunneling is only intended to emulate a point-to-point topology. An erroneous
Caution
configuration that sends tunneled packets to many ports could lead to a network failure.
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 enable 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 again 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.
OL-9640-10
Modification
This command was introduced.
Cisco ME 3400 Ethernet Access Switch Command Reference
l2protocol-tunnel
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