H3C S5600 SERIES Operation Manual page 234

Figure 1-4 Basic MSTP terminologies
A
B
D
Region D0:
VLAN 1 mapped to MSTI 1, B
as the regional root bridge
VLAN 2 mapped to MSTI 2, C
as the regional root bridge
Other VLANs mapped to CIST
MST region
A multiple spanning tree region (MST region) comprises multiple physically-interconnected
MSTP-enabled switches and the corresponding network segments connected to these switches. These
switches 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 switches into one MST
region by using the corresponding MSTP configuration commands.
As shown in Figure 1-4, all the switches in region A0 are of the same MST region-related configuration,
including:
Region name
VLAN-to-MSTI mapping (that is, VLAN 1 is mapped to MSTI 1, VLAN 2 is mapped to MSTI 2, and
the other VLANs are mapped to CIST.)
MSTP revision level (not shown in
MSTI
A multiple spanning tree instance (MSTI) refers to a spanning tree in an MST region.
Multiple spanning trees can be established in one MST region. These spanning trees are independent
of each other. For example, each region in
Each of these spanning trees corresponds to a VLAN.
VLAN-to-MSTI mapping table
A VLAN-to-MSTI mapping table is maintained for each MST region. The table is a collection of
mappings between VLANs and MSTIs. For example, in
region A0 contains these mappings: VLAN 1 to MSTI 1; VLAN 2 to MSTI 2, and other VLANs to CIST. In
an MST region, load balancing is implemented according to the VLAN-to-MSTI mapping table.
BPDU BPDU
CST
C
BPDU
Figure 1-4)
Figure 1-4
1-11
Region A0:
VLAN 1 mapped to MSTI 1
VLAN 2 mapped to MSTI 2
Other VLANs mapped to CIST
Region B0:
VLAN 1 mapped to MSTI 1
VLAN 2 mapped to MSTI 2
Other VLANs mapped to CIST
Region C0:
VLAN 1 mapped to MSTI 1
VLAN 2 and 3 mapped to MSTI 2
Other VLANs mapped to CIST
contains multiple spanning trees known as MSTIs.
Figure 1-4, the VLAN-to-MSTI mapping table of