What are the new flags which RSTP BPDU's introduces?

Question

Accepted Answer

RSTP BPDU introduces two new flags: TCN and Proposal.

TCN (Topology Change Notification) flag is used to indicate a topology change in the network.
Proposal flag is used to speed up the convergence process by allowing a switch to immediately transition to the forwarding state.
TCN flag is set by the root bridge and propagated to all switches in the network.
Proposal flag is set by a switch and sent to the root bridge.
Both flags are included in the BPDU message.
TCN flag triggers a topology change event and recalculates the spanning tree.
Proposal flag is used during the root bridge selection process.
RSTP BPDU also includes a new field called Message Age which indicates the age of the BPDU message.
RSTP BPDU also introduces a new port state called Discarding state which is a replacement for the Blocking state in STP.

Accepted Answer

Proposal, Agreement, Port roles

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