Spanning Tree Features Placement

[Tareq Emad Al Asfoor]

Hi all , 

During my googling i founded this topology below for Spanning Tree Features Placement, I just wonder why the Loopguard used only on these specific ports on the topology why not used on all ports , the same thing for RootGuard and so on ,,,    

Kind Regards, 

Tariq.E

[marce1000]

 -  In standard networking spanning tree convergence will be sufficient to have an operational network ; do no go into loop-guard or root-guard unless there are well defined requirements.

 M.

[Tareq Emad Al Asfoor]

Thanks for your replay ... Yes, but i was mean in this topology these features applied on specific ports not all ports !!  Is this mean any feature such as LoopGurad should applied on specific ports on topology or can applied on any port ?  Is there rule where to apply these features on ports ?

[Seb Rupik]

Loopguard should be applied on inter-switch connections where you expect to receive a BPDU. It is the absence of a BPDU being received that should be of concern to the switch so it places it in a loop-inconsistent blocking state.

cheers,

Seb.

[Tareq Emad Al Asfoor]

Thanks .. As i know the LoopGuard working with unidirectional link failure .. So any change in the topology will change the loop-inconsistent blocking state .. This mean i have to expect to receive the BPDU from any port in the topology ..

[Tareq Emad Al Asfoor]

Kindly is there any update ?

Kind Regards

[Seb Rupik]

You should expect to receive a BPDUs on ports connected to any switch. You will want to use BPDU-Guard on switchports not connected to your own switches to ensure rogue switches cannot effect the STP topology and potentially become the root bridge.

For the ports connecting your own switches together configure Loop Guard. On these ports you expect to (and want to ) receive BPDUs, if you don't place the port in an inconsistent state to prevent switching loops from forming.

cheers,

Seb.