R0106-HP MSR Router Series Layer 2 - LAN Switching Configuration Guide(V7)

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3 GigabitEthernet2/1/3 DESI FORWARDING NONE
# Display brief spanning tree information on Device C.
[DeviceC] display stp brief
MST ID Port Role STP State Protection
0 GigabitEthernet2/1/1 DESI FORWARDING NONE
0 GigabitEthernet2/1/2 ROOT FORWARDING NONE
0 GigabitEthernet2/1/3 DESI FORWARDING NONE
1 GigabitEthernet2/1/1 ROOT FORWARDING NONE
1 GigabitEthernet2/1/2 ALTE DISCARDING NONE
4 GigabitEthernet2/1/3 DESI FORWARDING NONE
# Display brief spanning tree information on Device D.
[DeviceD] display stp brief
MST ID Port Role STP State Protection
0 GigabitEthernet2/1/1 ROOT FORWARDING NONE
0 GigabitEthernet2/1/2 ALTE DISCARDING NONE
0 GigabitEthernet2/1/3 ALTE DISCARDING NONE
3 GigabitEthernet2/1/1 ROOT FORWARDING NONE
3 GigabitEthernet2/1/2 ALTE DISCARDING NONE
4 GigabitEthernet2/1/3 ROOT FORWARDING NONE
Based on the output, you can draw each MSTI mapped to each VLAN, as shown in Figure 20.
Figure 20 MSTIs mapped to different VLANs
PVST configuration example
Network requirements
As shown in Figure 21:
• Device A and Device B work at the distribution layer.
A
B
A B
C D
C
B
C
MSTI 1 mapped to VLAN 10
A
D D
Root bridge Normal link Blocked link
MSTI 3 mapped to VLAN 30
MSTI 0 mapped to VLAN 20
MSTI 4 mapped to VLAN 40