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 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-te-1/1)#spanning-tree pvst vlan 3 cost 1800
Dell(conf-if-te-1/1)#end
Dell(conf-if-te-1/1)#show config
!
interface TenGigabitEthernet 1/1
no ip address
switchport
spanning-tree pvst vlan 3 cost 1800
no shutdown
Dell(conf-if-te-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.
S6000
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,
refer to 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
9.7(0.0) Introduced on the S6000-ON.
1238 Per-VLAN Spanning Tree Plus (PVST+)