Basic Mstp Terminologies - 3Com WX3000 Series Operation Manual

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