Motorola RFS7000 Series System Reference Manual page 207

• Common Spanning (CST) – MST runs a single spanning tree instance (called the Common Spanning
Tree) that interconnects all the bridges in a network. This instance treats each region as a single
bridge. In all other ways, it operates exactly like Rapid Spanning Tree (RSTP).
• Common and Internal Spanning Trees (CIST) – CIST contains all of the ISTs and bridges not formally
configured into a region. This instance interoperates with bridges running legacy STP and RSTP
implementations.
• Multiple Spanning Tree Instance (MSTI) – The MSTI is identified by an MST identifier (MSTid) value
from 1 and 15. This defines an individual instance of a spanning tree. One or more VLANs can be
assigned to an MSTI. A VLAN cannot be assigned to multiple MSTIs. The multiple spanning tree
instance 0 is always present. VLANs not explicitly assigned to an instance are assigned to instance 0.
• MSTP Region – These are clusters of bridges that run multiple instances of the MST protocol.
Multiple bridges detect they are in the same region by exchanging their configuration (instance to
VLAN mapping), name, and revision-level. If you need to have two bridges in the same region, the
two bridges must have identical configurations, names, and revision-levels.
To configure the switch for MST support, configure the name and the revision on each switch being configured.
This name is unique to each region. Then create an Instance and assign an ID. VLANs are then assigned to
instances. These instances must be configured on switches that interoperate with the same VLAN
assignments. Port cost, priority and global parameters can then be configured for individual ports and
instances.
The Multiple Spanning Tree option contains separate tabs for the following activities:
• Configuring a Bridge
• Viewing and Configuring Bridge Instance Details
• Configuring a Port
• Viewing and Configuring Port Instance Details
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Network Setup