Rapid Spanning-Tree (RSTP)

Hello David

There is a little bit more detail that’s involved here as far as what goes on when a new link between two RSTP switches comes up. As soon as a new link comes up, both ports on either end of the link go into Designated Discarding state. Rene calls it “blocking state” which is a more generic term we use for STP in general. Designated DIscarding is the default state in RSTP as soon as a port comes up.

Every Designated Discarding port sends BPDUs with the proposal bit set to 1. This bit is set to indicate to the other switch that the initial negotiation is to take place. That means that both SW1 and SW2 will send these BPDUs. Rene focuses on the BPDU being sent from SW1 to SW2 in the lesson, because this is the only relevant exchange since SW1 will be the root bridge. Any BPDU sent by SW2 to SW1 will simply be ignored.

I hope this has been helpful!


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