Configuring Spanning Tree
Configuration Example for MSTP
User Guide
343
Figure 5-2
VLAN-Instance Mapping
Gi1/0/1
Gi1/0/2
Gi1/0/2
Gi1/0/2
Gi1/0/1
Gi1/0/1
Switch C
Switch A
Instance 1: VLAN 101 -VLAN 103
Instance 2: VLAN 104 -VLAN 106
Blocked Port
Switch B
The overview of configuration is as follows:
1) Enable MSTP function globally in all the switches.
2) Enable Spanning Tree function on the ports in each switch.
3) Configure Switch A, Switch B and Switch C in the same region. Configure the region
name as 1, and the revision level as 100. Map VLAN 101 - VLAN 103 to instance 1 and
VLAN 104 - VLAN 106 to instance 2.
4) Configure the priority of Switch B as 0 to set it as the root bridge in instance 1;
configure the priority of Switch C as 0 to set it as the root bridge in instance 2.
5) Configure the path cost to block the specified ports. For instance 1, set the path cost
of port 1/0/1 of Switch A to be greater than the default path cost (200000); for instance
2, set the path cost of port 1/0/2 of Switch B to be greater than the default path cost
(200000). After this configuration, port 1/0/2 of Switch A in instance 1 and port 1/0/1
of Switch B in instance 2 will be blocked for they cannot be neither root port nor
designated port.
Note:
Please configure MSTP for each switch first and then connect them together to avoid broadcast
storm.
5.3 Using the GUI
■
Configurations for Switch A
1) Choose the menu
L2 FEATURES > Spanning Tree > STP Config > STP Config
to load
the following page. Enable MSTP function globally, here we leave the values of the other
global parameters as default settings.
Click Apply
.
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