3com 8807 사용자 가이드
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C
HAPTER
17: MSTP R
EGION
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CONFIGURATION
Figure 23 Basic MSTP concepts
MST region
Multiple Spanning Tree Regions: A multiple spanning tree region contains several
switches and the network segments between them. These MSTP switches share
the same region name, VLAN-spanning tree mapping configuration, and MSTP
revision level configuration, and are connected directly. There can be several MST
regions on a switching network. You can group several switches into a MST
region, using MSTP configuration commands. For example, in Figure 23, the four
switches in MST region A0 are configured with the same region name, the same
VLAN mapping table (VLAN1 is mapped to instance 1, VLAN 2 is mapped to
instance 2, other VLANs is mapped to instance CIST), and the same revision level
(not indicated in Figure 23).
switches and the network segments between them. These MSTP switches share
the same region name, VLAN-spanning tree mapping configuration, and MSTP
revision level configuration, and are connected directly. There can be several MST
regions on a switching network. You can group several switches into a MST
region, using MSTP configuration commands. For example, in Figure 23, the four
switches in MST region A0 are configured with the same region name, the same
VLAN mapping table (VLAN1 is mapped to instance 1, VLAN 2 is mapped to
instance 2, other VLANs is mapped to instance CIST), and the same revision level
(not indicated in Figure 23).
VLAN mapping table
The VLAN mapping table is an attribute of MST region. It is used for describing the
mapping relationship of VLANs and spanning tree instances (STIs). For example, in
the VLAN mapping table of MST region A0 in Figure 23, VLAN1 is mapped to
instance 1, VLAN 2 is mapped to instance 2, other VLANs is mapped to CIST.
mapping relationship of VLANs and spanning tree instances (STIs). For example, in
the VLAN mapping table of MST region A0 in Figure 23, VLAN1 is mapped to
instance 1, VLAN 2 is mapped to instance 2, other VLANs is mapped to CIST.
In the same region, the mapping relationship of VLANs and STIs must be
consistent on all the switches in this region. Otherwise, VLAN and STI are not in
the same region.
consistent on all the switches in this region. Otherwise, VLAN and STI are not in
the same region.
IST
Internal Spanning Tree (IST): a spanning tree in a MSTP region. The IST and the
Common Spanning Tree (CST), together make up a Common and Internal
Spanning Tree (CIST) for the entire switching network. The IST in a MST region is a
fragment of the CIST. For example, every MST region in Figure 23 has an IST,
which is a fragment of CIST.
Common Spanning Tree (CST), together make up a Common and Internal
Spanning Tree (CIST) for the entire switching network. The IST in a MST region is a
fragment of the CIST. For example, every MST region in Figure 23 has an IST,
which is a fragment of CIST.
C
A
B
BPDU
BPDU
BPDU
CIST: common and
internal spanning tree
internal spanning tree
MSTI: multiple spanning
tree instance
tree instance
CST: common
spanning tree
Area A0
VLAN 1 mapped to Instance 1
VLAN 2 mapped to Instance 2
Other VLANs mapped to CIST
VLAN 1 mapped to Instance 1
VLAN 2 mapped to Instance 2
Other VLANs mapped to CIST
D
Area B0
VLAN 1 mapped to Instance 1
VLAN 2 mapped to Instance 2
Other VLANs mapped to CIST
VLAN 1 mapped to Instance 1
VLAN 2 mapped to Instance 2
Other VLANs mapped to CIST
Area C0
VLAN 1 mapped to Instance 1
VLANs 2 and 3 mapped to Instance 2
Other VLANs mapped to CIST
VLAN 1 mapped to Instance 1
VLANs 2 and 3 mapped to Instance 2
Other VLANs mapped to CIST
Area D0
VLAN 1 mapped to Instance
1, domain root as B
VLAN 2 mapped to Instance
2, domain root as C
Other VLANs mapped to
CIST
VLAN 1 mapped to Instance
1, domain root as B
VLAN 2 mapped to Instance
2, domain root as C
Other VLANs mapped to
CIST