Users Guide

Command
History
This guide is platform-specific. For command information about other platforms, see the relevant Dell
EMC Networking OS Command Line Reference Guide.
Version Description
9.12(1.0) Introduced on the S5048F–ON.
9.10(0.1) Introduced on the S6010-ON and S4048T-ON.
9.10(0.0) Introduced on the S3148.
9.10(0.0) Introduced on the S6100-ON.
9.8(2.0) Introduced on the S3100 series.
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 misconfigured, 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 configured as an edge port, on an RSTP switch, immediately transitions to the
Forwarding state. Only configure 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
configure loop guard on a port on which root guard is already configured, 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 traffic from flowing through it. For example, when Portfast BPDU guard
and loop guard are both configured:
● 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.
Example
DellEMC(conf)# interface twentyFiveGigE 1/1
DellEMC(conf-if-tf-1/1)# spanning-tree rstp edge-port
DellEMC(conf-if-tf-1/1)# show config
!
1342 Rapid Spanning Tree Protocol (RSTP)