STP_RSTP_PVST_MSTP

 

Medium-Sized Switched Network Construction

PVST+ (Per-VLAN Spanning Tree Protocol)

On this topology Two VLANs, one equal 10 and second equal 20, are being

 trunked across these links.

objectif  is to configure S3 as the root bridge forVLAN 20 and S1 as the root

 bridge for VLAN 10. 

Port F0/3 on S2 is the forwarding port for VLAN 20 and the blocking port for

 VLAN 10. Port F0/2 on S2 is

 the forwarding port for VLAN 10 and the blocking port for VLAN 20.

Activate pvst

Verify pvst ieee

 Primary and Secondary Root Bridges for Each VLAN on S3

S3(config)#  spanning-tree vlan 20 root primary
S3(config)# spanning-tree vlan 10 root secondary        

Primary and Secondary Root Bridges for Each VLAN on S1                                  

S1(config)# spanning-tree vlan 10 root primary
S1(config)# spanning-tree vlan 20 root secondary

Configuring the Lowest Possible Priority to Ensure That a Switch Is Root

S3(config)#  spanning-tree vlan 20 priority 4096

S1(config)# spanning-tree vlan 10 priority 409