Allied Telesis AT-S60 - Manual (Page 215)

Chapter 12: STP, RSTP, and MSTP
Section II: Local and Telnet Management 214
Figure 76 illustrates the same two AT-8400 Series switches and the same
two virtual LANs. But in this example, the two switches are running MSTP
and the two VLANs have been assigned different spanning tree
instances. Now that they reside in different MSTIs, both links remain
active, enabling the VLANs to forward traffic over their respective direct
link.
Figure 76 MSTP Example of Two Spanning Tree Instances
AT-8400 SERIES
AT-8400 SERIES
Sales
VLAN in
MSTI 1
Production
VLAN in
MSTI 2
Untagged
Ports
Untagged
Ports