Reference Guide
Enter the optional keyword shutdown-on-violation to
hardware disable an interface when a BPDU is received and
the port is disabled.
priority priority Enter keyword priority followed by a number as the
priority. The range is zero (0) to 15. The default is
8.
Defaults cost = depends on the interface type; priority = 8
Command
Modes
INTERFACE
Command
History
Version 8.3.10.1 Introduced the loopguard and rootguard options on the
S4810.
Version 8.4.2.1 Introduced the loopguard and rootguard options on the
E-Series TeraScale, C-Series, and S-Series.
Version 8.3.7.0 Introduced on the S4810.
Version 8.2.1.0 Introduced the shutdown-on-violation option.
Version 7.7.1.0 Introduced on the S-Series.
Version 7.5.1.0 Introduced on the C-Series.
Version 6.2.1.1 Introduced on the E-Series.
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 you do not enable shutdown-on-violation, BPDUs
still are 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+).
Root guard is supported on any STP-enabled port or port-channel except when
used as a stacking port. When enabled on a port, root guard applies to all VLANs
configured on the port.
STP root guard and loop guard cannot be enabled at the same time on a port. For
example, if you configure loop guard on a port on which root guard is already
configured, the following error message is displayed: % Error: RootGuard is
configured. Cannot configure LoopGuard.
Do not enable Portfast BPDU guard and loop guard at the same time on a port.
Enabling both features may result in a port that remains in a blocking state and
prevents traffic from flowing through it. For example, when Portfast BPDU guard
and loop guard are both configured:
Spanning Tree Protocol (STP)
1901