Huawei AR3200 Series - Page 235

Figure 8-4 MSTP network
CIST Root
A0
B0
C0
D0
Region Root
Region Root
Region Root
CST
IST
l CST
A Common Spanning Tree (CST) connects all the MST regions on a switching network.
Each MST region can be considered a node. A CST is calculated by using STP or RSTP
based on all the nodes.
As shown in Figure 8-4, the MST regions are connected to form a CST.
l IST
An IST resides within an MST region.
An IST is a special MSTI with an MSTI ID of 0, called MSTI 0.
An IST is a segment of the CIST in an MST region.
As shown in Figure 8-4, the switching devices in an MST region are connected to form an
IST.
l CIST
A CIST, calculated by using STP or RSTP, connects all the switching devices on a switching
network.
As shown in Figure 8-4, the ISTs and the CST form a complete spanning tree (CIST).
l SST
A Single Spanning Tree (SST) is formed in either of the following situations:
– A switching device running STP or RSTP belongs to only one spanning tree.
Huawei AR3200 Series Enterprise Routers
Configuration Guide - LAN 8 MSTP Configuration
Issue 02 (2012-03-30) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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