Alcatel-Lucent AOS-W 6.5.3.x - Pvst; Understanding PVST+ Interoperability and Best Practices; Enabling PVST+ in the CLI

AOS-W 6.5.3.x | User Guide PVST+ | 655
Chapter 25
PVST+
PVST+ (Per-VLAN Spanning Tree Plus) provides load-balancing of VLANs across multiple ports, resulting in
optimal usage of network resources. PVST+ also ensures interoperability with industry-accepted PVST+
protocols.
PVST+ is disabled by default.
Topics in this chapter include:
n Understanding PVST+ Interoperability and Best Practices on page 655
n Enabling PVST+ in the CLI on page 655
n Enabling PVST+ in the WebUI on page 656
Understanding PVST+ Interoperability and Best Practices
Interoperability between RSTP and PVST+ includes:
n When the access port on the switch and the trunk port terminate on one Layer 2 switch running PVST+,
PVST+ sends 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 Alcatel-Lucent switch is the root, it detects a
loop on the native VLAN.
If PVST+ is not on the switch, best practices recommend disabling RSTP on the Alcatel-Lucent switch to avoid a
looping issue.
n For VLAN load balancing when switches 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.
n 64 instances are supported on the OAW-40xx Series and OAW-4x50 Series switches.
Enabling PVST+ in 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