RSTP fast convergence

Hello,

RSTP implements fast convergence by improving the STP protocol.

The link is point-to-point, and RSTP changes to the forwarding state based on the P/A fast convergence:
The upstream device sends the Proposal packet and starts the waiting timer.
The downstream device blocks all other ports and sends back the Agreement packet to the upstream device.
The upstream device receives the Agreement packet and the port enters the forwarding state.
The preceding process is repeated between all upstream devices and downstream devices, implementing the fast convergence on the entire RSTP network.

NOTE:

The P/A fast convergence cannot be implemented for non-point-to-point links.
If a Huawei device is connected to a device from other manufacturers, run the stp no-agreement check command to implement fast convergence.

Thanks

Hi YaminaMD,

RSTP considers that the network topology has changed when a non-edge port transitions to the Forwarding state.

When detecting a topology change, RSTP devices react as follows:

The local device starts a TC While timer on each non-edge designated port. The TC While timer value is twice the Hello timer value.

Within the TC While time, the local device deletes MAC address entries learned on ports whose states have changed. These ports send out RST BPDUs with the TC bit set to 1. When the TC While timer expires, the ports stop sending RST BPDUs.

When other switches receive RST BPDUs, they clear MAC address entries learned on all their ports except the ports that receive the RST BPDUs. These switches also start a TC While timer on each non-edge designated port and repeat the preceding process.

For more information, please refer to https://support.huawei.com/hedex/hdx.do?docid=EDOC1100126530&id=EN-US_CONCEPT_0186953012&lang=en

I hope it helps!