User's Manual

186
Figure 176 Basic concepts in MSTP
MST region
A multiple spanning tree region (MST region) consists of multiple devices in a switched network and the
network segments among them. All these devices have the following characteristics:
• A spanning tree protocol enabled.
• Same region name.
• Same VLAN-to-instance mapping configuration.
• Same MSTP revision level.
• Physically linked with one another.
Multiple MST regions can exist in a switched network. You can assign multiple devices to the same MST
region. In Figure 176,
the switched network comprises four MST regions, MST region A0 through MST
region D0, and all devices in each MST region have the same MST region configuration.
MSTI
MSTP can generate multiple independent spanning trees in an MST region, and each spanning tree is
mapped to a range of VLANs. Each spanning tree is referred to as a "multiple spanning tree instance
(MSTI)".
In Figure 176,
multiple MSTIs can exist in each MST region, each MSTI corresponding to the specified
VLANs.