Dell 6.2 Chapte r 27

DellPowerConnect W- Series ArubaOS 6.2 | User Guide PVST+ | 490
Chapte r 27
PVST+
PVST+ (Per-VLAN Spanning Tree Plus) provides for load balancing of VLANs across multiple ports resulting in
optimal usage of networkresources. PVST+ also ensures interoperability with industry accepted PVST+ protocols.
NOTE:PV ST+ is disabled by default.
Topics in this chapter include:
l"UnderstandingPVST+ Interoperability and Best Practices" on page 490
l"EnablingPV ST+ in the CLI" on page 490
l"EnablingPV ST+ in the WebUI" on page 491
Understanding PV ST+ Interoperability and Best Prac tices
The interoperability between RSTP and PVST+ are:
lWhenthe access port on t hecontroller and the trunk port terminate on one Layer2 switch running PVST+,
PVST+ will send untaggedSTP BP DUs on the access port; it also transmits untagged STP BPDUs (in additio n
to the other PVST+ BPDUs) on the native VLAN t runkport. If the Dell controller is the root, it will detect a
loop on the native VLAN.
NOTE:If PVST+ i snot on the controller, best practices recommends disabli ng RSTP on the Dell controller to avoid a looping issue.
lFor VLAN load balancingwhen Dell controllers areconnected to armed mode, the VLAN priorities on two ports
and bridgeprioriti es must be configuredso that one set of VLANs are active on one link and the other set of
VLANs are active on the ot herlink.
lSupportedinstances are 6 4 on the W-7200 Series, W-6000M3, and W-3000 Series; 32 on the W-600 Series.
Enabling PVST+ in the CL I
PVST+ is disabled by default.Enable PVST+, ensure a VLAN instance is configured,and then configure PVST+.
1. E nablePV ST+:
spanning-tree mode rapid-pvst
2. Co nfigurePVST+ forward time; the following command sets the time VLAN 2 spends in the listening and
learningstate (3 seconds).
spanning-tree vlan 2 forward-time 3
3. Co nfigurePVST+ hello time; the following command sets the time VLAN 2 waits to transmit BPDUs to four
seconds:
spanning-tree vlan 2 hello-time 4