3Com WX3000 operation manual Basic Mstp Terminologies, MST region

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MSTP supports mapping VLANs to MST instances by means of a VLAN-to-instance mapping table. MSTP introduces “instance” (integrates multiple VLANs into a set) and can bind multiple VLANs to an instance, thus saving communication overhead and improving resource utilization.

MSTP divides a switched network into multiple regions, each containing multiple spanning trees that are independent of one another.

MSTP prunes a ring network into a network with tree topology, preventing packets from being duplicated and forwarded in a network endlessly. Furthermore, it offers multiple redundant paths for forwarding data, and thus achieves load balancing for forwarding VLAN data.

MSTP is compatible with STP and RSTP.

Basic MSTP Terminologies

Figure 1-4 illustrates basic MSTP terms (assuming that MSTP is enabled on every device in this figure).

Figure 1-4Basic MSTP terminologies

MST region

A multiple spanning tree region (MST region) comprises multiple physically-interconnected MSTP-enabled devices and the corresponding network segments connected to these devices. These devices have the same region name, the same VLAN-to-MSTI mapping configuration and the same MSTP revision level.

A switched network can contain multiple MST regions. You can group multiple devices into one MST region by using the corresponding MSTP configuration commands.

As shown in Figure 1-4, all the devices in region A0 are of the same MST region-related configuration, including:

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Region name

VLAN-to-MSTI mapping (that is, VLAN 1 is mapped to MSTI 1, VLAN 2 is mapped to instance 2, and the other VLANs are mapped to CIST.)

MSTP revision level (not shown in Figure 1-4)

1-10