Configuring MSTP
6. MSTI receiving port
These parameters exist prior, the superior the more precedence.
23.3.4 Determining MSTP
Determining MSTP divide into two parts, first starts CIST priority vectors, then MSTI priority
vectors.
Figure 23-9
As figure1-9,suppose all the cost of the ports in the whole bridge is equal, “MST
brige-1”—“MST brige-9”the identify increase by step，“SST bridge” is the most one.
23.3.4.1 Determining CIST Priority Vectors
1. The election of CIST root bridge, CIST root port
Throughout the bridged LAN, MST bridge 1 bridge priority of the highest identity, was
selected as the CIST root bridge. Assuming Region 2, Region 3 to the CIST root bridge of the
external root path cost is 1. Therefore, the bridge 8 MST CIST bridge priority vector update
(MST bridge 1,1, MST Bridge 8,0, MST Bridge 8), MST bridge 8 port x is the CIST root port;
MST CIST bridge priority bridge 9 level vector update (MST bridge 1,1, MST Bridge 9,0, MST
Bridge 9). Similarly, MST bridge port 3 f is the CIST root port.
2. The election of each domain CIST regional root bridge (IST root bridge), CIST root port
CIST
CIST root bridge was elected, they begin to select the various regions of the CIST regional
root bridge. To Region 3 as an example:
MST Bridge 7 Port u receive MST CIST bridge 8 priority vector (MST Bridge 1,1, MST
Bridge 8,0, MST bridge 8, v), with its own port u (MST Bridge 7,0, MST Bridge 7 , 0, MST
bridge 7, u) compared to that of MST Bridge 8 better, so the information is updated to the port
u (MST bridge 1,1, MST Bridge 8,0, MST bridge 8, v); Similarly, t update the port information
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