Dell S6100 Configuration Manual page 1577

Version
9.7(0.0)
9.2(1.0)
9.0.2.0
8.3.19.0
8.3.11.1
8.3.10.1
8.4.2.1
8.3.7.0
8.2.1.0
7.7.1.0
7.5.1.0
6.2.1.1
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 are still 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:
•
•
To display the type of STP guard (Portfast BPDU, root, or loop guard) enabled on a port, enter the show
spanning-tree 0 command.
Description
Introduced on the S6000-ON.
Introduced on the Z9500.
Introduced on the S6000.
Introduced on the S4820T.
Introduced on the Z9000.
Introduced the loopguard and rootguard options on the S4810.
Introduced the loopguard and rootguard options on the E-Series, C-Series, and S-
Series.
Introduced on the S4810.
Introduced the shutdown-on-violation option.
Introduced on the S-Series.
Introduced on the C-Series.
Introduced on the E-Series.
If a BPDU is received from a remote device, BPDU guard places the port in an Err-Disabled Blocking state and
no traffic is forwarded on the port.
If no BPDU is received from a remote device, loop guard places the port in a Loop-Inconsistent Blocking state
and no traffic is forwarded on the port.
Spanning Tree Protocol (STP) 1577