Command Line Reference Guide

Spanning Tree Protocol (STP) | 1353
spanning-tree
c e s
Configure Spanning Tree group id, cost, loop guard, priority, Portfast, and root guard for an interface.
Syntax
spanning-tree stp-id [cost cost] [loopguard | rootguard] [portfast [bpduguard
[shutdown-on-violation]]] [priority priority]
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 loop guard and root guard are supported on a port or port-channel enabled in any Spanning Tree
mode: Spanning Tree Protocol (STP), Rapid Spanning Tree Protocol (RSTP), Multiple Spanning Tree
Protocol (MSTP), and Per-VLAN Spanning Tree Plus (PVST+).
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
[loopguard]
(OPTIONAL) Enter the keyword loopguard to enable STP loop guard on a port or
port-channel interface.
priority priority (OPTIONAL) Enter keyword priority followed by a number as the priority.
Range: zero (0) to 15. Default: 8
portfast
[bpduguard
[
shutdown-on-viol
ation
]]
(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.
Enter the keyword
shutdown-on-violation to hardware disable an interface when a
BPDU is received and the port is disabled.
[rootguard]
(OPTIONAL) Enter the keyword rootguard to enable STP root guard on a port or
port-channel interface.
Version 8.4.2.0
Introduced the loopguard and rootguard options on the E-Series TeraScale, C-Series, and S-Series
Version 8.2.1.0 Introduced 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