Allied Telesis AT-S62 - Manual (Page 359)

AT-S62 User’s Guide
Section IV: Spanning Tree Protocols 359
The revision level is an arbitrary number you assign to a region. You can
use the number to keep track of the revision level of a region’s
configuration. For example, you might use this value to maintain the
number of times you revise a particular MSTP region. It is not important
that you maintain this number, only that each bridge in a region have
the same number.
The bridges of a particular region must also have the same VLANs. The
names of the VLANs and the VIDs must be same on all bridges of a
region.
Finally, the VLANs in the bridges must be associated to the same MSTIs.
If any of the above information is different on two bridges, MSTP
considers the bridges as residing in different regions.