a.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:

∙MSTP-enabled

∙Same region name

∙Same VLAN-to-MSTI mapping configuration

∙Same MSTP revision level

∙Physically linked together

All the devices in region A0 in a have the same MST region configuration:

∙The same region name

∙The same VLAN-to-MSTI mapping configuration (VLAN 1 is mapped to MSTI 1, VLAN 2 to MSTI 2, and the rest to the common and internal spanning tree (CIST, that is, MSTI 0)

∙The same MSTP revision level (not shown in the figure)

Multiple MST regions can exist in a switched network. You can assign multiple devices to the same MST region.

VLAN-to-MSTI mapping table

As an attribute of an MST region, the VLAN-to-MSTI mapping table describes the mapping relationships between VLANs and MSTIs. In a, the VLAN-to-MSTI mapping table of region A0 is: VLAN 1 is mapped to

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