Specifications

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Cisco ME 3400 Ethernet Access Switch Command Reference

OL-9640-07

Chapter 2 Cisco ME 3400 Ethernet Access Switch Cisco IOS Commands

spanning-tree

Use the spanning-tree interface configuration command with no keywords on an enhanced network

interface (ENI) to enable a spanning-tree instance on the interface. Use the no form of this command to

return to the default setting of disabled.

spanning-tree

no spanning-tree

Syntax Description This command has no arguments or keywords.

Defaults The Spanning-Tree Protocol (STP) is disabled on ENIs.

Command Modes Interface configuration

Command History

Usage Guidelines This command is supported only on ENIs and on EtherChannel port channels that contain ENIs.

STP is not supported on user network interfaces (UNIs) and it is disabled by default on ENIs. Use this

command to enable SPT on an ENI. To set a port as an ENI, enter the port-type eni interface

configuration command. Once STP is enabled on an ENI, all other STP interface configuration

commands are available on the interface.

The switch supports only one spanning-tree instance on a VLAN. When NNIs and ENIs with spanning

tree enabled are in the same VLAN, they belong to the same spanning-tree instance.

STP is enabled by default on NNIs. UNIs are typically customer-facing ports and do not participate in

the spanning tree of the service provider. However, if you configure a customer-facing port as an ENI

and enable spanning tree, the ENI could become the spanning tree root port unless you configure root

guard on the port by using the spanning-tree guard root interface configuration command. A

customer-facing ENI with STP enabled participates in the same spanning tree as the service-provider

facing NNI.

Note Exercise caution when enabling STP on a customer-facing ENI.

Examples This example shows how to enable STP on a port:

Switch(config)# interface fastethernet0/1

Switch(config-if)# port-type eni

Switch(config-if)# spanning-tree

You can verify your setting by entering the show spanning-tree interface privileged EXEC command.

Release Modification

12.2(44)SE This command (without keywords) was introduced.