Allied Telesis AT-S63 - Manual (Page 250)

Chapter 22: Multiple Spanning Tree Protocol
250 Section V: Spanning Tree Protocols
Another approach is to group those VLANs that need to span regions into
the same MSTI. Those VLANs that do not span regions can be assigned
to other MSTIs.
Here is an example. Assume that you have two regions that contain the
following VLANS:
Region 1 VLANs Region 2 VLANs
Sales Hardware Engineering
Presales Software Engineering
Marketing Technical Support
Advertising Product Management
Technical Support CAD Development
Product Management Accounting
Project Management
Accounting
The two regions share three VLANs: Technical Support, Product
Management, and Accounting. You could group those VLANs into the
same MSTI in each region. For instance, for Region 1 you might group the
three VLANs in MSTI 11 and in Region 2 you could group them into MSTI
6. After they are grouped, you can connect the VLANs across the regions
using a link of tagged ports.