Cisco ME 3600X User Manual

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Cisco ME 3800X and ME 3600X Switch Command Reference
OL-28238-01
Chapter
spanning-tree portfast (global configuration)
Caution Enabling BPDU filtering on an STP port is the same as disabling spanning tree on it and can result in
spanning-tree loops.
Use the spanning-tree portfast bpduguard default global configuration command to globally enable
BPDU guard on STP ports that are in a Port Fast-operational state. In a valid configuration, Port
Fast-enabled STP ports do not receive BPDUs. Receiving a BPDU on a Port Fast-enabled STP port
signals an invalid configuration, such as the connection of an unauthorized device, and the BPDU guard
feature puts the STP port in the error-disabled state. The BPDU guard feature provides a secure response
to invalid configurations because you must manually put the STP port back in service. Use the BPDU
guard feature in a service-provider network to prevent an access port from participating in the spanning
tree.
You can override the spanning-tree portfast bpduguard default global configuration command by
using the spanning-tree bdpuguard interface configuration command on an STP port.
Use the spanning-tree portfast default global configuration command to globally enable the Port Fast
feature on all nontrunking STP ports. Configure Port Fast only on STP ports that connect to end stations;
otherwise, an accidental topology loop could cause a data packet loop and disrupt switch and network
operation. A Port Fast-enabled STP port moves directly to the spanning-tree forwarding state when
linkup occurs without waiting for the standard forward-delay time.
You can override the spanning-tree portfast default global configuration command by using the
spanning-tree portfast interface configuration command on an STP port. You can use the no
spanning-tree portfast default global configuration command to disable Port Fast on all STP ports
unless they are individually configured with the spanning-tree portfast interface configuration
command.
You can verify your settings by entering the show running-config privileged EXEC command.
Examples This example shows how to globally enable the BPDU filtering feature:
Switch(config)# spanning-tree portfast bpdufilter default
This example shows how to globally enable the BPDU guard feature:
Switch(config)# spanning-tree portfast bpduguard default
This example shows how to globally enable the Port Fast feature on all nontrunking interfaces:
Switch(config)# spanning-tree portfast default
Related Commands Command Description
show running-config Displays the operating configuration.
spanning-tree bpdufilter Prevents an interface from sending or receiving BPDUs.
spanning-tree bpduguard Puts an STP port in the error-disabled state when it receives a
BPDU.
spanning-tree portfast (interface
configuration)
Enables the Port Fast feature on an STP port in all its associated
VLANs.

Cisco ME 3600X Specifications

General

Brand	Cisco
Model	ME 3600X
Category	Switch
Language	English