Figure 2-15 Basic Concepts Of The Msti Network - Raisecom ISCOM2600G-HI (A) Series Configuration Manual

Raisecom
ISCOM2600G-HI (A) Series Configuration Guide
MSTP protocol introduces Common Spanning Tree (CST) and Internal Spanning Tree (IST)
concepts. CST refers to taking MST region as a whole to calculate and generating a spanning
tree. IST refers to generating spanning tree in internal MST region.
Compared with STP and RSTP, MSTP also introduces total root (CIST Root) and region root
(MST Region Root) concepts. The total root is a global concept; all switches running
STP/RSTP/MSTP can have only one total root, which is the CIST Root. The region root is a
local concept, which is relative to an instance in a region. As shown in Figure 2-15, all
connected devices only have one total root, and the number of region root contained in each
region is associated with the number of instances.

Figure 2-15 Basic concepts of the MSTI network

There can be different MST instance in each MST region, which associates VLAN and MSTI
by configuring the VLAN mapping table (relationship table of VLAN and MSTI). The
concept sketch map of MSTI is shown in Figure 2-16.
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