Spanning tree protocal per vlan

Unanswered Question
Feb 13th, 2009


We have 6500 catalyst in our two office and they are connected through one fiber and copper now we have two path between the sites

so i need to enable STP to block one port and allow other in terms of primary fails

the vlan ID Is VLAN 2 were fibre and copper connected

I need to know whether STP is best option are we need to choose some other

I have this problem too.
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Giuseppe Larosa Fri, 02/13/2009 - 03:23

Hello Vinoth,

PVST+ should be already running

verify with

show spanning-tree vlan 2

And yes STP is thought to be used to manage L2 links redundancy

Hope to help


ccannon88567 Fri, 02/13/2009 - 03:39

Personally, I would always prefer Etherchannelling (or LACP) over spanning tree for l2 redundancy where possible.

However, in this case it would not be recommended due to mixed media links.

Keep in mind for others though - spanning-tree can be complicated and there are more benfits of channeling such as bandwidth aggregation in addition to just redundancy.


vinoth.kumar Fri, 02/13/2009 - 03:51

thanks for the reply

How i can priorities the link which should be the forwarding which link be blocking

As per my idea since we are using fibre and copper which as the different port cost (4 and 19) fiber will be the forwarding port and copper will be the blocking

pls suggest me

ccannon88567 Fri, 02/13/2009 - 04:08

Show spanning-tree command with vlan ID will tell you under Status...

mcr-sw_gateway_01#sh spanning-tree vlan 2


Spanning tree enabled protocol ieee

Root ID Priority 4098

Address 000d.295e.dc80

This bridge is the root

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 4098 (priority 4096 sys-id-ext 2)

Address 000d.295e.dc80

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Aging Time 300

Interface Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Fa1/0/11 Desg FWD 100 128.13 P2p

Fa1/0/20 Desg FWD 19 128.22 P2p

Fa1/0/24 Desg FWD 19 128.26 P2p

Fa2/0/19 Desg FWD 19 128.73 Shr

Fa2/0/20 Desg FWD 19 128.74 P2p

Fa2/0/21 Desg FWD 19 128.75 P2p

Fa2/0/22 Desg FWD 19 128.76 P2p

Fa2/0/23 Desg FWD 19 128.77 P2p


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