vStpInsNumber 1.3.6.1.4.1.6486.800.1.2.1.12.1.1.1.3.1.1

The Spanning Tree number identifying this instance. In 1x1 mode the accepted range is 1-4095 and corresponds to the VLAN. In Flat mode the range is 0-4095 and corresponds to the Spanning tree instance.