Allied Telesis AT-S62 - Manual (Page 480)

Chapter 24: Multiple Spanning Tree Protocol
Section IV: Spanning Tree Protocols 480
Multiple
Spanning Tree
Instance (MSTI)
The individual spanning trees in MSTP are referred to as Multiple
Spanning Tree Instances (MSTIs). A MSTI can span any number of
switches. An AT-8500 Series switch can support up to 16 MSTIs at a time.
To create a MSTI, you first assign it a number, referred to as the MSTI ID.
The range is 1 to 15. (The switch comes with a default MSTI with an MSTI
ID of 0. This default spanning tree instance is discussed later in Common
and Internal Spanning Tree (CIST) on page 488.)
Once you have selected an MSTI ID, you need to define its scope by
assigning one or more VLANs to it. An instance can contain any number
of VLANs, but a VLAN can belong to only one MSTI at a time.
Here are a couple of examples. Figure 165 illustrates two AT-8524M
switches, each containing the two VLANs Sales and Production. The two
parts of each VLAN are connected with a direct link using untagged
ports on both switches.