Reference Guide

1142 | Spanning Tree Protocol (STP)
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spanning-tree
c e s z
Configure Spanning Tree group id, cost, priority, and Portfast for an interface.
Syntax
spanning-tree stp-id [cost cost] [portfast [bpduguard]] [priority priority]
To disable Spanning Tree group on an interface, use the no spanning-tree stp-id [cost cost]
[portfast [bpduguard] [shutdown-on-violation]] [priority priority] command.
Parameters
Defaults
cost = depends on the interface type; priority = 8
Command Modes
INTERFACE
Command
History
Usage
Information
If you enable portfast bpduguard on an interface and the interface receives a BPDU, the software
disables the interface and sends a message stating that fact. The port is in ERR_DISABLE mode, yet
appears in the show interface commands as enabled.
If shutdown-on-violation is not enabled, BPDUs will still be sent to the RPM CPU.
stp-id
Enter the Spanning Tree Protocol group ID.
Range: 0
cost cost (OPTIONAL) Enter the keyword cost followed by a number as the cost.
Range: 1 to 65535
Defaults:
• 100 Mb/s Ethernet interface = 19
• 1-Gigabit Ethernet interface = 4
• 10-Gigabit Ethernet interface = 2
• Port Channel interface with 100 Mb/s Ethernet = 18
• Port Channel interface with 1-Gigabit Ethernet = 3
• Port Channel interface with 10-Gigabit Ethernet = 1
priority priority (OPTIONAL) Enter keyword priority followed by a number as the priority.
Range: zero (0) to 15.
Default: 8
portfast
[bpduguard]
(OPTIONAL) Enter the keyword portfast to enable Portfast to move the interface into
forwarding mode immediately after the root fails.
Enter the keyword
bpduguard to disable the port when it receives a BPDU.
shutdown-on-
violation
(OPTIONAL) Enter the keyword shutdown-on-violation to hardware disable an
interface when a BPDU is received and the port is disabled.
Version 8.3.11.1 Introduced on Z9000
Version 8.2.1.0 Introduced hardware shutdown-on-violation option
Version 7.7.1.0 Introduced on S-Series
Version 7.5.1.0 Introduced on C-Series
Version 6.2.1.1 Introduced