Allied Telesis AT-S62 - Manual (Page 513)

AT-S62 Management Software Menus Interface User’s Guide
Section IV: Spanning Tree Protocols 513
two or more ports have equal costs to a regional root bridge. Again, as
with the internal path cost, you can assign a port a different priority value
for each of its MSTIs.
Multiple
Spanning Tree
Regions
Another important concept of MSTP is regions. A MSTP region is defined
as a group of bridges that share exactly the same MSTI characteristics.
Those characteristics are:
ˆ Configuration name
ˆ Revision level
ˆ VLANs
ˆ VLAN to MSTI ID associations
A configuration name is a name you assign to a region to help you identify
it. You must assign each bridge in a region exactly the same name, even
the same upper and lowercase lettering. Identifying the regions in your
network is easier if you choose names that are characteristic of the
functions of the nodes and bridges of the region. Examples are Sales
Region and Engineering Region.
The revision level is an arbitrary number you can 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.