Rapid Spanning Tree Question

[Tom de Brouwer]

All,

I have a question about Rapid Spanning Tree reconfiguration. I have to following situation:

As you can see 3 switches with RSTP, and 2 switches without RSTP (or any other spanning tree, just unmanaged).

The 2 switch will form a loop in my network. Switch 1 will block one of the ports and the other port will forward the traffic.
If I break the link "Just Forwarding", my second switch won't be able to cumminucate for around 40 seconds. It will take some time before the backup link will be up again.

Cisco has the Fastforwarding  mechanism. Will this help in this situation? I would like to shorten the 40 seconds time.

Thans in advance.

[cmarva · Accepted solution]

I'd guess the unmanaged devices run legacy spanning tree, and rapid
pvst switches will run rapid according the "heard" protocol. So if it hears

the legacy bpdu, it will run regular spanning tree, hence the 40 second delay.

chris