Administrator Guide

rootguard Enter the keyword rootguard to enable root guard on an RSTP port or port-channel
interface.
Defaults Not congured.
Command Modes INTERFACE
Command History
This guide is platform-specic. For command information about other platforms, see the relevant Dell Networking
OS Command Line Reference Guide.
Version Description
9.8(1.0) Introduced on the Z9100-ON.
9.8(0.0P5) Introduced on the S4048-ON.
9.8(0.0P2) Introduced on the S3048-ON.
9.7(0.0) Introduced on the S6000-ON.
9.2(1.0) Introduced on the Z9500.
9.0.2.0 Introduced on the S6000.
8.3.19.0 Introduced on the S4820T.
8.3.11.1 Introduced on the Z9000.
8.4.2.1 Added support for the optional guard keyword on the C-Series, S-Series, and E-Series.
8.3.7.0 Introduced on the S4810.
8.2.1.0 Introduced the hardware shutdown-on-violation options.
7.6.1.0 Introduced on the S-Series.
7.5.1.0 Introduced on the C-Series.
7.4.1.0 Added the optional bridge port data unit (BPDU) guard.
6.2.1.1 Introduced on the E-Series.
Usage Information
The BPDU guard option prevents the port from participating in an active STP topology in case a BPDU appears
on a port unintentionally, or is miscongured, or is subject to a DOS attack. This option places the port into an Error
Disable state if a BPDU appears and a message is logged so that the administrator can take corrective action.
NOTE: A port congured as an edge port, on an RSTP switch, immediately transitions to the
Forwarding state. Only congure ports connected to end-hosts as edge ports. Consider an edge port
similar to a port with a spanning-tree portfast enabled.
If you do not enable shutdown-on-violation, BPDUs are still sent to the RPM CPU.
You cannot enable STP root guard and loop guard at the same time on a port. For example, if you congure loop
guard on a port on which root guard is already congured, the following error message displays: % Error:
RootGuard is configured. Cannot configure LoopGuard
.
Enabling Portfast BPDU guard and loop guard at the same time on a port results in a port that remains in a
Blocking state and prevents trac from owing through it. For example, when Portfast BPDU guard and loop
guard are both congured:
• If a BPDU is received from a remote device, BPDU guard places the port in an Err-Disabled Blocking state and
no trac is forwarded on the port.
Rapid Spanning Tree Protocol (RSTP) 1369