Digital Data Communications Level One GTL-2091 User manual

STP Optional Characteristic
Configuration Commands
(GTL-2091)
V1.0
Digital Data Communications GmbH, Germany.
http://www.level1.com

Table of Contents
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Table of Contents
Chapter 1 STP Optional Characteristic Configuration Commands...................................................................................1
1.1 STP Optional Characteristic Configuration Commands ....................................................................................1
1.1.1 spanning-tree portfast .........................................................................................................................1
1.1.2 spanning-tree bpduguard ....................................................................................................................2
1.1.3 spanning-tree bpdufilter.......................................................................................................................3
1.1.4 spanning-tree uplinkfast ......................................................................................................................4
1.1.5 spanning-tree backbonefast ................................................................................................................4
1.1.6 spanning-tree guard............................................................................................................................5
1.1.7 spanning-tree loopguard .....................................................................................................................6

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STP Optional Characteristic Configuration Commands
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Chapter 1 STP Optional Characteristic Configuration
Commands
1.1 STP Optional Characteristic Configuration Commands
1.1.1 spanning-tree portfast
Description
To enable bridge protocol data unit (BPDU) filtering by default on all PortFast ports,
use the spanning-tree portfast command in global configuration mode. To return to
the default settings, use the negative form of this command.
spanning-tree portfast {bpdufilter default | bpduguard default | default}
no spanning-tree portfast {bpdufilter default | bpduguard default | default}
To enable PortFast mode where the interface is immediately put into the forwarding
state upon linkup without waiting for the timer to expire, use the spanning-tree portfast
command in interface configuration mode. To return to the default settings, use the
negative form of this command.
spanning-tree portfast [disable | trunk]
no spanning-tree portfast
Parameter
Parameter
Description
bpdufilter default
Enables bpdu flter.
bpduguard default
Enables bpdu guard.
default
Specifies the default method.
Default
Disabled
Instruction
In SSTP/PVST mode, the Port Fast characteristic makes a port immediately enter
Forwarding state without experiencing any status change process. This configuration is
invalid in RSTP/MSTP mode.

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STP Optional Characteristic Configuration Commands
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After configuring Port Fast, BPDU Guard or BPDU Filter needs to be configured for
protection.
Command mode
Global or interface configuration mode
Example
This example shows how to enable PortFast mode globally:
Console_config# spanning-tree portfast default
Console_config#
This example shows how to enable PortFast mode on the interface f0/0:
Console_config_f0/0# spanning-tree portfast
Console_config_f0/0#
1.1.2 spanning-tree bpduguard
Description
To enable bridge protocol data unit (BPDU) guard on the interface, use the
spanning-tree bpduguard command in interface configuration mode. To return to the
default settings, use the negative form of this command.
spanning-tree bpduguard {disable | enable}
no spanning-tree bpduguard
Parameter
None
Default
Disabled
Instruction
In SSTP/PVST mode, if a port that configured BPDU Guard and Port Fast receives
BPDU, this port will be forced to shutdown. User can restore it by the manual
configuration. In RSTP/MSTP mode, if a port that configured BPDU Guard receives
BPDU, this port will be configured to Blocking state for a period of time.

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STP Optional Characteristic Configuration Commands
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Command mode
Interface configuration
Example
This example shows how to enable BPDU guard on this interface:
Console_config_f0/0# spanning-tree bpduguard enable
Console_config_f0/0#
1.1.3 spanning-tree bpdufilter
Description
To enable bridge protocol data unit (BPDU) filtering on the interface, use the
spanning-tree bpdufilter command in interface configuration mode. To return to the
default settings, use the negative form of this command.
spanning-tree bpdufilter {disable |enable}
no spanning-tree bpdufilter
Parameter
None
Default
Disabled
Instruction
In SSTP/PVST mode, if a port that configured BPDU Filter and Port Fast receives
BPDU, the BPDU Filter and Port Fast characteristics on that port will be disabled
automatically to restore the port to an ordinary port. Then this port must endure the
wait from Listening to Learning before entering Forwarding state.
This feature is invalid in RSTP/MSTP mode.
Command mode
Interface configuration
Example
This example shows how to enable BPDU filtering on this interface:
Console_config_f0/0# spanning-tree bpdufilter enable

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STP Optional Characteristic Configuration Commands
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Console_config_f0/0#
1.1.4 spanning-tree uplinkfast
Description
To enable the debugging of the spanning-tree UplinkFast events, use the debug
spanning-tree uplinkfast command. To disable the debugging output, use the
negative form of this command.
spanning-tree uplinkfast [max-update-rate pkts-per-second]
no spanning-tree uplinkfast [max-update-rate]
Parameter
None
Default
disabled
Instruction
Uplink Fast characteristic is only valid in SSTP/PVST mode.
Command mode
Global configuration
Example
The following example enables uplinkfast characteristic:
Console_config# spanning-tree uplinkfast
Console_config#
1.1.5 spanning-tree backbonefast
Description
To enable debugging of the spanning-tree BackboneFast events, use the debug
spanning-tree backbonefast command. To disable the debugging output, use the
negative form of this command.
spanning-tree backbonefast

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STP Optional Characteristic Configuration Commands
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no spanning-tree backbonefast
Parameter
None
Default
Disabled
Instruction
Backbone Fast characteristic is only valid in SSTP/PVSTmode.
Command mode
Global configuration
Example
The following command enables backbonefast characteristic:
Console_config# spanning-tree backbonefast
Console_config#
1.1.6 spanning-tree guard
Description
To enable or disable the guard mode, use the spanning-tree guard command in
interface configuration mode. To return to the default settings, use the negative form of
this command.
spanning-tree guard {loop | none | root}
no spanning-tree guard
Parameter
Parameter
Description
loop
Enables the loop-guard mode on the interface. Value is from 1
to 0xfe.
none
Sets the guard mode to none. Value is 48-bit.
root
Enables root-guard mode on the interface.

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STP Optional Characteristic Configuration Commands
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Default
Disabled
Instruction
Root Guard characteristic can prevent a port from becoming Root port due to receving
high priority BPDU.
Loop Guard characteristic can protect a Root Port or a Alternate Port when it becomes
the Designated Port. This function can prevent a port from occuring the loop when it
cannot continuously receive BPDU.
Command mode
Interface configuration
Example
This example shows how to enable root guard:
Console_config_f0/0# spanning-tree guard root
Console_config_f0/0#
1.1.7 spanning-tree loopguard
Description
To enable loop guard as a default on all ports of a given bridge, use the spanning-tree
loopguard default command in global configuration mode. To disable loop guard, use
the negative form of this command.
spanning-tree loopguard default
Parameter
None
Default
None
Instruction
None

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Command mode
Global configuration
Example
The following command enables loopguard function:
Console_config# spanning-tree loopguard default
Console_config#