Command Line Reference Guide

ManualsBrandsDell Manualscomputer componentsNetworking S5000

1021

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

FTOS(conf-if-te-1/1)#spanning-tree pvst vlan 3 cost 18000

FTOS(conf-if-te-1/1)#end

FTOS(conf-if-te-1/1)#show config

interface TenGigabitEthernet 1/1

no ip address

switchport

spanning-tree pvst vlan 3 cost 18000

no shutdown

FTOS(conf-if-te-1/1)#end

FTOS#

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.

S5000

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

Version 9.0(1.3) Introduced on the S5000.

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,

FTOS places the port in the Error-Disable state. This behavior might result in the network not

converging. To prevent FTOS from executing this action, use the no spanning-tree

pvst err-disable

command cause invalid-pvst-bpdu.

1030