Administrator Guide

Parameters
stp-id Enter the STP instance ID. The range is 0.
cost cost Enter the keyword cost then a number as the cost. The range is from 1 to 65535. The
defaults are:
• 10-Gigabit Ethernet interface = 2.
• Port Channel interface with 10-Gigabit Ethernet = 1.
portfast
[bpduguard
[shutdown-on-viol
ation]]
Enter the keyword portfast to enable Portfast to move the interface into Forwarding
mode immediately after the root fails.
Enter the optional keyword bpduguard to disable the port when it receives a BPDU.
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 then a number as the priority. The range is from zero (0) to 15.
The default is 8.
Defaults cost = depends on the interface type; priority = 8
Command Modes INTERFACE
Command History
This guide is platform-specific. For command information about other platforms, see the relevant Dell Networking
OS Command Line Reference Guide.
The following is a list of the Dell Networking OS version history for this command.
Version Description
9.9(0.0) Introduced on the C9010.
9.2(1.0) Introduced on the Z9500.
8.3.19.0 Introduced on the S4820T.
8.3.11.1 Introduced on the Z9000.
8.3.10.1 Introduced the loopguard and rootguard options on the S4810.
8.4.2.1 Introduced the loopguard and rootguard options on the E-Series TeraScale, C-
Series, and S-Series.
8.3.7.0 Introduced on the S4810.
8.2.1.0 Introduced the shutdown-on-violation option.
7.7.1.0 Introduced on the S-Series.
7.5.1.0 Introduced on the C-Series.
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 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:
Spanning Tree Protocol (STP) 1605