HP procurve 8100fl series Management And Configuration Manual page 119

Region "A": Logical Topology
Root for Instance 1
VLANs: 10, 11, 12
Switch "B"
Instance 1
VLANs: 10, 11, 12
Path blocked for VLANs in instance 1.
Region "A": Physical Topology
Figure 9-1. Example of a Multiple Spanning-Tree Application
For example, suppose you have three switches in a region configured with
VLANs grouped into two instances, as follows:
VLANs Instance 1
10, 11, 12 Yes
20, 21, 22 No
The logical and physical topologies resulting from these VLAN/Instance
groupings result in blocking on different links for different VLANs:
Switch "A"
Switch "C"
Instance 1
VLANs: 10, 11, 12
Root for Instance 1
Switch "B"
Root for Instance 2
Path blocked for VLANs in instance 1.
Instance 2
No
Yes
Switch "B"
Root for Instance 2
VLANs: 20, 21, 22
Switch "A"
Switch "C"
Spanning-Tree Operation
Path blocked for VLANs in instance 2.
Switch "A"
Instance 2
VLANs: 20, 21, 22
Switch "C"
Instance 2
VLANs: 20, 21, 22
Path blocked for VLANs in instance 2.
Overview
9-3