how to change root port direction if i have multiple backbones

[ajayaram48@gmail.com]

hi

any one can tell us how to change root port by using commands. in my organization we have two backbones one from 

directly connected l 3-switch gig-port another one from l 2 switch gig port but it is considering as port -port how to change root port direction i need to consider l 3 .

[balaji.bandi]

If i undertand the question correctly, are you looking spanning-tree root port ? please clarify

and provide show spann summary for the switches.

[ajayaram48@gmail.com · Accepted solution]

CONFHALL01#sh spanning-tree

VLAN0001
Spanning tree enabled protocol ieee
Root ID Priority 32769
Address 000b.5fa7.2e00
Cost 12084
Port 26 (GigabitEthernet0/2)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 49153 (priority 49152 sys-id-ext 1)
Address d057.4cfd.6a00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Uplinkfast enabled

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi0/1 Altn BLK 3004 128.25 P2p
Gi0/2 Root FWD 3004 128.26 P2p

[ajayaram48@gmail.com]

my switch has two backbones one from l-2 another from L-3 now as per S.T.P DATA port from l-2 Is the root port from  l-3  it is showing alternate-block port . i want to change root port direction from L-2 switch port to l-3 switch port because as per client requirement.please tell me how to change