93
[DeviceC] display stp brief
MSTID Port Role STP State Protection
0 Ethernet1/0/1 DESI FORWARDING NONE
0 Ethernet1/0/2 ROOT FORWARDING NONE
0 Ethernet1/0/3 DESI FORWARDING NONE
1 Ethernet1/0/1 ROOT FORWARDING NONE
1 Ethernet1/0/2 ALTE DISCARDING NONE
4 Ethernet1/0/3 DESI FORWARDING NONE
# Display brief spanning tree information on Device D.
[DeviceD] display stp brief
MSTID Port Role STP State Protection
0 Ethernet1/0/1 ROOT FORWARDING NONE
0 Ethernet1/0/2 ALTE DISCARDING NONE
0 Ethernet1/0/3 ALTE DISCARDING NONE
3 Ethernet1/0/1 ROOT FORWARDING NONE
3 Ethernet1/0/2 ALTE DISCARDING NONE
4 Ethernet1/0/3 ROOT FORWARDING NONE
Based on the output, you can draw the MSTI mapped to each VLAN, as shown in
Figure 25 MSTIs mapped to different VLANs
PVST configuration example
Network requirements
As shown in
:
•
Device A and Device B work at the distribution layer. Device C and Device D work at the access
layer.
•
Configure PVST so that packets of different VLANs are forwarded along different spanning
trees.
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