Users Guide

Table Of Contents
Dell PowerConnect W-Series ArubaOS 6.1 | User Guide PVST+ | 501
Chapter 26
PVST+
PVST+ (Per-VLAN Spanning Tree Plus) provides for load balancing of VLANs across multiple ports resulting in
optimal usage of network resources. PVST+ also ensures interoperability with industry accepted PVST+
protocols.
Interoperability and Best Practices
The interoperability between RSTP and PVST+ are:
When the access port on the controller and the trunk port terminate on one Layer 2 switch running PVST+,
PVST+ will send untagged STP BPDUs on the access port; it also transmits untagged STP BPDUs (in
addition to the other PVST+ BPDUs) on the native VLAN trunk port. If the Dell controller is the root, it will
detect a loop on the native VLAN.
For VLAN load balancing when controllers are connected to armed mode, the VLAN priorities on two ports
and bridge priorities must be configured so that one set of VLANs are active on one link and the other set of
VLANs are active on the other link.
Supported instances are 64 on the W-6000M3 and W-3000 Series; 32 on the W-600 Series
Configure using the CLI
PVST+ is disabled by default. Enable PVST+, ensure a VLAN instance is configured, and then configure
PVST+.
1. Enable PVST+:
spanning-tree mode rapid-pvst
2. Configure PVST+ forward time; the following command sets the time VLAN 2 spends in the listening and
learning state (3 seconds).
spanning-tree vlan 2 forward-time 3
3. Configure PVST+ hello time; the following command sets the time VLAN 2 waits to transmit BPDUs to four
seconds:
spanning-tree vlan 2 hello-time 4
4. Configure PVST+ max age; the following command sets the time VLAN 2 waits to receive a hello packet to
30 seconds:
spanning-tree vlan 2 max-age 30
5. Configure PVST+ priority: the following command sets the VLAN 2 priority to 10, making it more likely to
become the root bridge:
spanning-tree vlan 2 priority 10
NOTE: By default, PVST+ is disable.
NOTE: If PVST+ is not on the controller, best practices recommends disabling RSTP on the Dell controller to avoid a looping issue.