Reference Guide

By default, each VLAN instance is assigned default bridge priority 32768. For example, all three instances have the same
forwarding topology. Traffic load balancing is not achievable with this kind of priority assignment. You must assign each instance
a different priority to achieve load balancing, as shown in Load Balancing with RPVST+.
Load balance and root selection
All VLANs use the same forwarding topology — R2 is elected as the root and all 10G Ethernet ports have the same cost.
RPVST+ changes the bridge priority of each bridge so that a different forwarding topology generates for each VLAN.
To achieve RPVST+ load balancing, assign a different priority on each bridge.
Enable RPVST+
By default, RPVST+ is enabled and creates an instance only after you add the first member port to a VLAN. Port-channel or
physical interfaces must be a member of a VLAN to participate in RPVST+. Add all physical and port-channel interfaces to the
default VLAN (VLAN1).
● Enable the Rapid-PVST+ mode in CONFIGURATION mode.
spanning-tree mode rapid-pvst
Configure RPVST+
OS10(config)# spanning-tree mode rapid-pvst
View RPVST+ configuration
OS10# show spanning-tree active
Spanning tree enabled protocol rapid-pvst with force-version rstp
VLAN 1
Executing IEEE compatible Spanning Tree Protocol
Root ID Priority 32768, Address 3417.4455.667f
Root Bridge hello time 2, max age 20, forward delay 15
Bridge ID Priority 32769, Address 90b1.1cf4.a523
Configured hello time 2, max age 20, forward delay 15
Interface Designated
Name PortID Prio Cost Sts Cost Bridge ID PortID
------------------------------------------------------------------------
ethernet1/1/5 128.276 128 500 FWD 0 32768 3417.4455.667f 128.146
ethernet1/1/6 128.280 128 500 BLK 0 32768 3417.4455.667f 128.150
Interface
Name Role PortID Prio Cost Sts Cost Link-type Edge
Layer 2
213