Users Guide

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 Introduced the loopguard and rootguard options on the E-Series, C-Series, and S-
Series.
8.3.7.0 Introduced on the S4810.
8.2.1.0 Introduced the hardware shutdown-on-violation option.
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.
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 the 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 a PVST switch, immediately transitions to the forwarding
state. Only ports connected to end-hosts should be congured as an edge port. 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 route process module (RPM) CPU.
You cannot enable 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 is displayed: %
Error: RootGuard is configured. Cannot configure LoopGuard.
When used in a PVST+ network, loop guard is performed per-port or per-port channel at a VLAN level. If no
BPDUs are received on a VLAN interface, the port or port-channel transitions to a Loop-Inconsistent (blocking)
state only for this VLAN.
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.
1170
Per-VLAN Spanning Tree Plus (PVST+)