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MSTP Configuration Example

MSTP Configuration Example

Nov 28, 2023

There are two examples of MSTP configuration. In our first example, VLAN 100 is mapped to MSTI-1 and VLAN 200 is mapped to MSTI-2. The entire topology belongs to only one MSTP domain named region1. Switch A is the root of the network. 

To achieve load balancing, VLAN 100 should be in MSTI-1 (Fig. 4-4), and VLAN 200 should be in MSTI-2 (Fig. 4-5). 

 
Figure 4-3. MSTP configuration. 


 
Figure 4-4. MSTI-1 topology for VLAN 100. 


 
Figure 4-5. MSTI-2 topology for VLAN 200.


Configuring Switch A, Example 1

For Switch A, configure ge-1/1/1~ge-1/1/3 as trunk ports and as members of VLAN 100 and VLAN 200.

admin@XorPlus# set vlans vlan-id 100 admin@XorPlus# set vlans vlan-id 200 admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching port-mode trunk admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching vlan members 100 admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching vlan members 200 admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching port-mode trunk admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching vlan members 100 admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching vlan members 200 admin@XorPlus# set interface gigabit-ethernet ge-1/1/3 family ethernet-switching port-mode trunk admin@XorPlus# set interface gigabit-ethernet ge-1/1/3 family ethernet-switching vlan members 100 admin@XorPlus# set interface gigabit-ethernet ge-1/1/3 family ethernet-switching vlan members 200 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus# admin@XorPlus# set protocols spanning-tree mstp msti 1 vlan 100 admin@XorPlus# set protocols spanning-tree mstp msti 2 vlan 200 admin@XorPlus# set protocols spanning-tree mstp configuration-name region1 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus# To make sure that Switch A is the root of the network and the regional root of MSTI-1, configure it as the higher priority. admin@XorPlus# set protocols spanning-tree mstp bridge-priority 0 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus# set protocols spanning-tree mstp msti 1 bridge-priority 4096 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus#

Configuring Switch B, Example 1

Configure ge-1/1/1~ge-1/1/3 as trunk ports and as members of VLAN 100 and VLAN 200.

admin@XorPlus# set vlans vlan-id 100 admin@XorPlus# set vlans vlan-id 200 admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching port-mode trunk admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching vlan members 100 admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching vlan members 200 admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching port-mode trunk admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching vlan members 100 admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching vlan members 200 admin@XorPlus# set interface gigabit-ethernet ge-1/1/3 family ethernet-switching port-mode trunk admin@XorPlus# set interface gigabit-ethernet ge-1/1/3 family ethernet-switching vlan members 100 admin@XorPlus# set interface gigabit-ethernet ge-1/1/3 family ethernet-switching vlan members 200 admin@XorPlus# admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus# admin@XorPlus# set protocols spanning-tree mstp msti 1 vlan 100 admin@XorPlus# set protocols spanning-tree mstp msti 2 vlan 200 admin@XorPlus# set protocols spanning-tree mstp configuration-name region1 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus#

To verify that Switch B is the regional root of MSTI-2 and that ge-1/1/2 and ge-1/1/3 are in blocking status in MSTI-1, configure a higher MSTI-2 priority and a large value for internal-path-cost in MSTI-1.

admin@XorPlus# set protocols spanning-tree mstp msti 2 bridge-priority 4096 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus# admin@XorPlus# set protocols spanning-tree mstp msti 1 interface ge-1/1/2 cost 10000000 admin@XorPlus# set protocols spanning-tree mstp msti 1 interface ge-1/1/3 cost 10000000 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus#

Configuring Switch C, Example 1

Configure ge-1/1/1~ge-1/1/2 as trunk ports and as members of VLAN 100 and VLAN 200.

admin@XorPlus# set vlans vlan-id 100 admin@XorPlus# set vlans vlan-id 200 admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching port-mode trunk admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching vlan members 100 admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching vlan members 200 admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching port-mode trunk admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching vlan members 100 admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching vlan members 200 admin@XorPlus# admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus# admin@XorPlus# set protocols spanning-tree mstp msti 1 vlan 100 admin@XorPlus# set protocols spanning-tree mstp msti 2 vlan 200 admin@XorPlus# set protocols spanning-tree mstp configuration-name region1 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus#

To set ge-1/1/1 and ge-1/1/2 in forwarding status in MSTI-1, configure a lower value for internal-path-cost. 
To set ge-1/1/1 in blocking status in MSTI-2, configure a higher value for internal-path-cost.

admin@XorPlus# set protocols spanning-tree mstp msti 1 interface ge-1/1/1 cost 1000 admin@XorPlus# set protocols spanning-tree mstp msti 1 interface ge-1/1/2 cost 1000 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus# set protocols spanning-tree mstp msti 2 interface ge-1/1/1 cost 100000 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus#

Configuring Switch D, Example 1

Configure ge-1/1/1~ge-1/1/2 as trunk ports and as members of VLAN 100 and VLAN 200.

admin@XorPlus# set vlans vlan-id 100 admin@XorPlus# set vlans vlan-id 200 admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching port-mode trunk admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching vlan members 100 admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching vlan members 200 admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching port-mode trunk admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching vlan members 100 admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching vlan members 200 admin@XorPlus# admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus# admin@XorPlus# set protocols spanning-tree mstp msti 1 vlan 100 admin@XorPlus# set protocols spanning-tree mstp msti 2 vlan 200 admin@XorPlus# set protocols spanning-tree mstp configuration-name region1 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus#

To set ge-1/1/1 in blocking status in MSTI-2 and ge-1/1/2 in blocking status in MSTI-1, configure a large value for internal-path-cost.

admin@XorPlus# set protocols spanning-tree mstp msti 2 interface ge-1/1/1 cost 10000000 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus# set protocols spanning-tree mstp msti 1 interface ge-1/1/2 cost 10000000 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus#

Configuring Switch E, Example 1

Configure ge-1/1/1~ge-1/1/2 as trunk ports and as members of VLAN 100 and VLAN 200.

admin@XorPlus# set vlans vlan-id 100 admin@XorPlus# set vlans vlan-id 200 admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching port-mode trunk admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching vlan members 100 admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching vlan members 200 admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching port-mode trunk admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching vlan members 100 admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching vlan members 200 admin@XorPlus# admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus# admin@XorPlus# set protocols spanning-tree mstp msti 1 vlan 100 admin@XorPlus# set protocols spanning-tree mstp msti 2 vlan 200 admin@XorPlus# set protocols spanning-tree mstp configuration-name region1 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus#

To set ge-1/1/1 and ge-1/1/2 in forwarding status in MSTI-2, configure a lower value for internal-path-cost. 
To set ge-1/1/2 in blocking status in MSTI-1, configure a large value for internal-path-cost.

admin@XorPlus# set protocols spanning-tree mstp msti 2 interface ge-1/1/1 cost 1000 admin@XorPlus# set protocols spanning-tree mstp msti 2 interface ge-1/1/2 cost 1000 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus# set protocols spanning-tree mstp msti 1 interface ge-1/1/2 cost 10000000 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus#

In the second example, there are two regions. In region 1, VLAN 100 is mapped to MSTI-1, VLAN 200 is mapped to MSTI-2, and VLAN 300 is mapped to MSTI-3. In region 2, VLAN 200 is mapped to MSTI-2 and VLAN 400 is mapped to MSTI-4. Switch A is the root of the entire network. The topologies of the VLANs are presented in Fig. 4-6 through 4-10. 


Figure 4-6. MSTP configuration.



Figure 4-7. Topology for VLAN 100.



Figure 4-8. Topology for VLAN 200.


Figure 4-9. Topology for VLAN 300.


Figure 4-10. Topology for VLAN 400.

Configuring Switch A, Example 2

For Switch A, configure ge-1/1/1~ge-1/1/2 as trunk ports and as members of VLAN 100, VLAN 200, VLAN 300, and VLAN 400.

admin@XorPlus# set vlans vlan-id 100 admin@XorPlus# set vlans vlan-id 200 admin@XorPlus# set vlans vlan-id 300 admin@XorPlus# set vlans vlan-id 400 admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching port-mode trunk admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching vlan members 100 admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching vlan members 200 admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching vlan members 300 admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching vlan members 400 admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching port-mode trunk admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching vlan members 100 admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching vlan members 200 admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching vlan members 300 admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching vlan members 400 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus# admin@XorPlus# set protocols spanning-tree mstp msti 1 vlan 100 admin@XorPlus# set protocols spanning-tree mstp msti 2 vlan 200 admin@XorPlus# set protocols spanning-tree mstp msti 3 vlan 300 admin@XorPlus# set protocols spanning-tree mstp configuration-name region1 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus# To verify that Switch A is the root of the network and the regional root of MSTI-1, configure it as the higher priority. admin@XorPlus# set protocols spanning-tree mstp bridge-priority 0 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus# set protocols spanning-tree mstp msti 1 bridge-priority 4096 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus#

Configuring Switch B, Example 2

Configure ge-1/1/1~ge-1/1/3 as trunk ports and as members of VLAN 100, VLAN 200, VLAN 300, and VLAN 400.

admin@XorPlus# set vlans vlan-id 100 admin@XorPlus# set vlans vlan-id 200 admin@XorPlus# set vlans vlan-id 300 admin@XorPlus# set vlans vlan-id 400 admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching port-mode trunk admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching vlan members 100 admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching vlan members 200 admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching vlan members 300 admin@XorPlus# set interface gigabit-ethernet ge-1/1/1 family ethernet-switching vlan members 400 admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching port-mode trunk admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching vlan members 100 admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching vlan members 200 admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching vlan members 300 admin@XorPlus# set interface gigabit-ethernet ge-1/1/2 family ethernet-switching vlan members 400 admin@XorPlus# set interface gigabit-ethernet ge-1/1/3 family ethernet-switching port-mode trunk admin@XorPlus# set interface gigabit-ethernet ge-1/1/3 family ethernet-switching vlan members 100 admin@XorPlus# set interface gigabit-ethernet ge-1/1/3 family ethernet-switching vlan members 200 admin@XorPlus# set interface gigabit-ethernet ge-1/1/3 family ethernet-switching vlan members 300 admin@XorPlus# set interface gigabit-ethernet ge-1/1/3 family ethernet-switching vlan members 400 admin@XorPlus# admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus# admin@XorPlus# set protocols spanning-tree mstp msti 1 vlan 100 admin@XorPlus# set protocols spanning-tree mstp msti 2 vlan 200 admin@XorPlus# set protocols spanning-tree mstp msti 3 vlan 300 admin@XorPlus# set protocols spanning-tree mstp configuration-name region1 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus#

To verify that Switch B is the regional root of MSTI-2 and that ge-1/1/1 is in blocking status in MSTI-3, configure a higher MSTI-2 priority and a large value for internal-path-cost in MSTI-3.

admin@XorPlus# set protocols mstp msti 2 bridge-priority 4096 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus# admin@XorPlus# set protocols mstp msti 3 interface ge-1/1/1 cost 10000000 admin@XorPlus# commit Waiting for merging configuration. Commit OK. Save done. admin@XorPlus#

Configuring Switch C, Example 2

Configure ge-1/1/1~ge-1/1/3 as trunk ports and as members of VLAN 100, VLAN 200, VLAN 300, and VLAN 400.

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