H3C S7500 Series Operation Manual page 247

Operation Manual – MSTP
H3C S7500 Series Ethernet Switches
configuration: the same region name, the same VLAN-to-MSTI mappings (that is,
VLAN 1 is mapped to MSTI 1, VLAN 2 is mapped to MSTI 2, and other VLANs are
mapped to CIST), the same MSTP revision level (not shown in
II. 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 MSTIs are
independent of each other. For example, each region in
spanning trees known as MSTIs. Each of these spanning trees corresponds to the
specific VLANs.
III. VLAN mapping table
A VLAN mapping table is a property of an MST region. It contains information about
how VLANs are mapped to MSTIs. For example, in
contained in the VLAN mapping table of region A0 is: VLAN 1 is mapped to MSTI 1;
VLAN 2 is mapped to MSTI 2; and other VLANs are mapped to CIST. In an MST region,
load balancing is achieved by the VLAN mapping table.
IV. IST
An internal spanning tree (IST) is a spanning tree in an MST region.
ISTs together with the common spanning tree (CST) form the common and internal
spanning tree (CIST) of the entire switched network. An IST is a special MSTI; it
belongs to an MST region and is a segment of the CIST. In
has an IST, which is a segment of the CIST.
V. CST
A CST is the spanning tree in a switched network that connects all MST regions in the
network. If you regard each MST region in the network as a switch, then the CST is the
spanning tree generated by STP or RSTP running on the "switches". In
lines in red depict the CST.
VI. CIST
A CIST is the spanning tree in a switched network that connects all switches in the
network. It comprises the ISTs and the CST. In
and the CST connecting the MST regions form the CIST.
VII. Region root
A region root is the root of the IST or an MSTI in an MST region. Different MSTIs in an
MST region may have different topologies and thus have different region roots. In
region D0 shown in
of MSTI 2 is switch C.
Figure 1-1, the region root of MSTI 1 is switch B, and the region root
1-3
Chapter 1 MSTP Configuration
Figure
Figure 1-1
Figure 1-1, the information
Figure 1-1, each MST region
Figure 1-1, the ISTs in the MST regions
1-1).
contains multiple
Figure 1-1, the