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5. IMPLEMENTING SPANNING TREE PROTOCOL

HOW TO IMPLEMENTING MSTP
 
Task 1  
  
Configure dotlq trunks on ports fa0/9 and fa0/11. Configure VTP to propagate VLAN  
information. Configure instance 1 MSTP and map VLANs 1, 2, 3. Configure instance 2  
MSTP and map VLANs 4, 5, 6. Make SW1 the STP root for instances 1, 2.  
  
Switch1     
                                                        
                                                                    
Int range fa0/9, fa0/11                                            
Switchport trunk encapsulation dotlq                              
Switchport mode trunk                                            
  
Vtp domain netmet                                           
Vtp mode server                                             
Vtp password cisco123                                         
  
Vlan 2                                                       
Name aaa                                                        
Vlan 3                                                         
Name bbb                                                     
Vlan 4                                                              
Name ccc                                                            
Vlan5  
Name ddd  
Vlan 6  
Name 666  
 
Spanning-tree mode mst  
Spanning-tree mst configuration  
Instance 1 vlan 1 – 3  
Instance 2 vlan 4 – 6  
  
Spanning-tree mst 1 – 2 root primary 
 
 
Switch 
 
Int range fa0/9, fa0/11 
Switchport trunk encapsulation dotlq  
Switchport mode trunk 
 
Vtp domain netmet 
Vtp mode client 
Vtp password cisco123 
 
Spanning-tree mode mst 
Spanning-tree mst configuration 
Instance 1 vlan 1 – 3 
Instance 2 vlan 4 – 6
 
Verification:  
  
SW1#show  spanning-tree mst 1 
 
The output displays the VLANs mapped to this MST instance 1.  
  
SW1#show  spanning-tree mst 2  
 
The output displays the VLANs mapped to this MST instance 2.  
  
 
Task 2  
 
(Scenario Based On Task 1)  
  
Configure MSTP on SW1 & SW2. Make SW1 the STP root for instance 1. Make SW2  
the STP root for instance 2. Configure MST instance 1 and map VLANs 1 - 3. Configure  
MST instance 2 and map VLANs 4 - 6.
 
Switch1 
 
Spanning-tree mode mst 
Spanning-tree mst configuration 
Instance 1 vlan 1 – 3 
Instance 2 vlan 4 – 6 
 
Spanning-tree mst 1 root primary 
 
Switch2 
 
Spanning-tree mode mst 
Spanning-tree mst configuration 
Instance 1 vlan 1 – 3 
Instance 2 vlan 4 – 6 
 
Spanning-tree mst 2 root primary
 
 
Verification:  
  
SW1#show spanning-tree mst 1
 
The output displays that sw1 acts as the root bridge for vlans 1-3 only. 
 
This can be verified from the output that ports fa0/9 and fa0/11 are in forwarding state 
only for vlans 1-3 whereas one port forwarding and other blocking for vlans 4-6 on the 
same switch. 
 
SW2#show spanning-tree mst 1 
 
SW2#show spanning-tree mst 2
 
The output displays that sw2 acts as the root bridge for vlans 4-6 only. 
 
This can be verified from the output that ports fa0/9 and fa0/11 are in forwarding state 
only for vlans 4-6 whereas one port forwarding and other blocking for vlans 1-3 on the 
same switch.
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