Users Guide

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
Dell(conf-if-gi-1/1)# spanning-tree pvst vlan 3 cost 18000
Dell(conf-if-gi-1/1)# end
Dell(conf-if-gi-1/1)# show config
!
interface GigabitEthernet 1/1
no ip address
switchport
spanning-tree pvst vlan 3 cost 18000
no shutdown
Dell(conf-if-gi-1/1)#end
Dell#
Related
Commands
• show spanning-tree pvst — views the PVST+ configuration.
spanning-tree pvst err-disable
Place ports in an Err-Disabled state if they receive a PVST+ BPDU when they are members an untagged VLAN.
Syntax
spanning-tree pvst err-disable cause invalid-pvst-bpdu
Defaults Enabled; ports are placed in the Err-Disabled state if they receive a PVST+ BPDU when they are members of an
untagged VLAN.
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.
Version Description
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.
8.3.7.0 Introduced on the S4810.
8.2.1.0 Introduced.
Usage Information
Some non-Dell Networking systems which have hybrid ports participating in PVST+ transmit two kinds of BPDUs:
an 802.1D BPDU and an untagged PVST+ BPDU.
Dell Networking systems do not expect PVST+ BPDU on an untagged port. If this happens, Dell Networking OS
places the port in the Error-Disable state. This behavior might result in the network not converging. To prevent
1058 Per-VLAN Spanning Tree Plus (PVST+)