Basic Mstp Terminologies - Huawei Quidway S3100 Series Operation Manual

Operation Manual – MSTP
Quidway S3100 Series Ethernet Switches

1.1.2 Basic MSTP Terminologies

Figure 1-1 illustrates basic MSTP terms (assuming that MSTP is enabled on each
switch in this figure).
CIST: Common and Internal
MSTI: Multiple Spanning
Region A0
vlan 1 mapping to Instance 1, region root B
vlan 3 mapped to Instance 2
Other vlans mapped to CIST
Figure 1-1 Basic MSTP terminologies
I. MST region
An MST
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-spanning-tree 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. For
example, all switches in region A0 shown in Figure 1-1 have the same MST region
configuration: the same region name, the same VLAN-to-spanning-tree mappings (that
is, VLAN 1 is mapped to spanning tree instance 1, VLAN 2 is mapped to spanning tree
instance 2, and other VLANs are mapped to CIST), the same MSTP revision level (not
shown in Figure 1-1).
II. MSTI
A multiple spanning tree instance (MSTI) refers to a spanning tree in a 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 Figure 1-1 contains
multiple spanning trees known as MSTIs (multiple spanning tree instances). Each of
these spanning trees corresponds to a VLAN.
Spanning Tree
Tree Instance
BPDU
A
B
C
D
, region root C
region (multiple
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Region A0
vlan 1 mapped to Instance 1
vlan 2 mapped to Instance 2
Other vlans mapped to CIST
BPDU
CST: Common
Spanning Tree
BPDU
Region C0
vlan 1 mapped to Instance 1
vlan 2 and 3 mapped to Instance 2
Other vlans mapped to CIST
spanning tree
1-2
Chapter 1 MSTP Configuration
Region B0
vlan 1 mapped to Instance 1
vlan 2 mapped to Instance 2
Other vlans mapped to CIST
region) comprises multiple