How RSTP works

During RSTP calculation, the following events occur:

• If a port in discarding state becomes an alternate port, it retains its state.

• If a port in discarding state is elected as the root port or designated port, it enters the learning state after the forward delay. The port learns MAC addresses, and enters the forwarding state after another forward delay.

  • A newly elected RSTP root port rapidly enters the forwarding state if the following requirements are met:

    • The old root port on the device has stopped forwarding data.

    • The upstream designated port has started forwarding data.

  • A newly elected RSTP designated port rapidly enters the forwarding state if one of the following requirements is met:

    • The designated port is configured as an edge port which directly connects to a user terminal.

    • The designated port connects to a point-to-point link and receives a handshake response from the directly connected device.