Overview of RPVST+

NOTE:

For information on configuring basic and multiple instance spanning tree, see Multiple instance spanning tree operation.

RPVST+ is a proprietary spanning tree implementation that extends RSTP (802.1w) to run a separate spanning tree for each VLAN on the switch, and ensures that only one active, loop-free path exists between any two nodes on a given VLAN.

RPVST scalability

Platform

Maximum Allowed RPVST Enabled VLANs

Recommended Maximum Virtual Ports

Maximum Allowed Virtual Ports (x is the number of logical ports in the system)

2930

128

400

2000 + x

Where x is the sum of all physical ports and logical interface, such as Trk1 if configured.

The following shows how x is calculated using the 2920 switch as an example, you can substitute the actual values for your switch as shown in the table to do a similar calculation. In a stack of 4 with 2x2920-24 and 1 trunk interface Trk1 configured, x will be 24+24+1=49. Therefore the maximum allowed vPorts is 299.

Switch# show spanning-tree system-limits rapid-pvst

 Spanning Tree Information 

  STP Enabled              : No 
  Mode                     : MSTP 
  RPVST Enabled VLANs      : 1,4,20-23 

  Switch MAC Address                   : 40a8f0-0df69e 
  Count of RPVST Enabled GVRP VLANs    : 0 
  Count of RPVST Enabled VLANs         : 6 
  Maximum Allowed RPVST Enabled VLANs  : 64 
  Count Of Total Virtual Ports         : 51 
  Maximum Allowed Virtual Ports        : 299

                       Current         Operational     Recommended Maximum 
  Ports                Virtual Ports   Virtual Ports   Virtual Ports 
  -------------------- --------------- --------------- -------------------- 
  Member 1/1-24        31              27              250 
  Member 2/1-24        31              24              250