Allied Telesis AT-S60 - Manual (Page 259)

AT-S60 Management Software User’s Guide
Section II: Advanced Features 259
Note
Due to different vendor implementations of the new IEEE 802.1s
standard, compatibility issues concerning MSTP instances between
the AT-8400 Series switch and switches from other vendors may
exist. This can result in compatibility issues between different MSTP
implementations. For this release, MSTP is compatible only with
other AT-8400 Series switches.
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
AT-8400 Series switches, and an AT-8400 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 267.)
Once you have selected an MSTI ID, you need to define the scope of the
MSTI 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 84 illustrates two AT-8400 Series
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.