MSTP & RSTP : question

[f-vanryckeghem]

Hi all,

Just one question, I use the MSTP on 3550 platform just to use the RSTP fonctionnality, as the RSTP is not yet implemented on IOS.

My question is: If I put all my vlan's in on single MST instance, do I have one spanning tree per vlan or not ...?

or do I have to put one vlan per instance to have that ?

Best regards

Frederic

[gubci]

RSTP and MSTP are bound together.

To your question:

Yes and no.

On 3550 you will have one spanning tree. However if you will have classic STP switch(device) connected to port of 3550, 3550 will comunicate with that switch over classic PVST protocol. so basicaly it will proces as many BPDUs as many VLANs you will have...

If you connect MSTP capable switch, they will communicate depend if they are in the same region, resp. instance mapping via as many BPDUs as many different instances they have....

hope it'll help.