Manual
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Switch3(Config-Mstp-Region)#exit 
Switch3(config)#interface e1/1-7 
Switch3(Config-Port-Range)#switchport mode trunk 
Switch3(Config-Port-Range)#exit 
Switch3(config)#spanning-tree 
Switch3(config)#spanning-tree mst 3 priority 0 
Switch4:  
Switch4(config)#vlan 20 
Switch4(Config-Vlan20)#exit 
Switch4(config)#vlan 30 
Switch4(Config-Vlan30)#exit 
Switch4(config)#vlan 40 
Switch4(Config-Vlan40)#exit 
Switch4(config)#vlan 50 
Switch4(Config-Vlan50)#exit 
Switch4(config)#spanning-tree mst configuration 
Switch4(Config-Mstp-Region)#name mstp 
Switch4(Config-Mstp-Region)#instance 3 vlan 20;30 
Switch4(Config-Mstp-Region)#instance 4 vlan 40;50 
Switch4(Config-Mstp-Region)#exit 
Switch4(config)#interface e1/1-7 
Switch4(Config-Port-Range)#switchport mode trunk 
Switch4(Config-Port-Range)#exit 
Switch4(config)#spanning-tree 
Switch4(config)#spanning-tree mst 4 priority 0 
After the above configuration, Switch1 is the root bridge of the instance 0 of the entire network. 
In the MSTP region which Switch2, Switch3 and Switch4 belong to, Switch2 is the region root 
of the instance 0, Switch3 is the region root of the instance 3 and Switch4 is the region root of 
the  instance  4.  The  traffic  of  VLAN  20  and  VLAN  30  is  sent  through  the  topology  of  the 
instance 3. The traffic of VLAN 40 and VLAN 50 is sent through the topology of the instance 4. 
And the traffic of other VLANs is sent through the topology of the instance 0. The port 1 in 
Switch2 is the master port of the instance 3 and the instance 4. 
The MSTP calculation generates 3 topologies: the instance 0, the instance 3 and the instance 
4  (marked  with  blue  lines).  The  ports  with  the  mark  “x”  are  in  the  status  of  discarding.  The 
other ports are the status of forwarding. Because the instance 3 and the instance 4 are only 
valid in the MSTP region, the following figure only shows the topology of the MSTP region. 










