1. The blocking state only applies to data traffic. BPDUs are sent to a special destination mac address (in the "reserved range" of the IEEE spec) that are still received on blocked ports.
2. The proposal/agreement is purely local on a segment. Basically, when you are a designated port, you are proposing as long as you are blocking. If you receive an agreement, you go forwarding immediately else you keep proposing until the timers expire and go forwarding.
3. Modern networks are p2p. If you're a designated port connected to a backup or alternate port, it means that you're designated to a link that is not used. There is not much interest in going forwarding fast on this. However, the standard has been modified and the latest implementations should send back an agreement on alternate and backup ports too.
2. all this is local, it's not like all the bridges have to agree on a root and then we start deciding the roles of the ports. Ports have a role. When a port is selected as designated, if it is currently blocking, then it proposes in order to speed up its way out of the blocking state (a designated port is bound to be forwarding eventually). If it cannot go forwarding quickly, it uses the forward delay to do this slowly.
3. forward delay is used to put a port to forwarding in STP. RSTP just shortcuts the timers by adding some intelligence.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...