What will happen if, SW1, SW2, SW3 are managed RSTP ring switches. And I add unmanaged SW4 and SW5 the ring (both SW4 and SW5 are connected together) like this:
This project is currently at early stage. We are just trying to figure out if the hardware-specific client demand is feasible. Going with the unmanaged switches solution would reduce costs significantly.
Sel-2730M configurations will use BPDU Guard.
The "unmanaged" portion (blue portion in the diagram) of the network wont have any loops.
Best Answer
If the unmanaged switches do not support RSTP, they should forward the BPDUs as any other L2 multicast and simply flood them out the VLAN. If they do, things will work fine since the managed switches will receive the BPDUs. The unmanagad switches would basically be transparent to the managed switches from a STP perspective.
Worst case the switches would consume the BPDUs but not act on them and create a bridging loop. I've never seen this myself but heard of such stories from others.