4.4.2.3 RSTP Introduction
RSTP (Rapid Spanning Tree Protocol) is an optimized version of STP. It is “fast”
because the delay is shortened under certain conditions when a port is selected as the root port
and designated port to enter the forwarding state. Thus, the time to reach topology stability is
greatly reduced.
In RSTP, to ensure the root port moves fast - the old root port of the device has to stop forwarding
data and the upstream designated port has to start forwarding data.
In RSTP, to ensure the designated port moves fast - the designated port should be an edge port or a
port connected to a point to point link. If the designated port is an edge port, then the designated port
can enter the forwarding state. If the designated port is connected to a point to point link, the device
can handshake with the downstream device to give immediate response to enter the forwarding state.
On the [LACP / RSTP] page you can observe the current port RSTP information on the switch shown
in the figure below:
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CLASSIFICATION
DESIGNATED BRIDGE
DESIGNATED PORT
FOR EQUIPMENT
Equipment connecting directly
with switch and responsible to
transfer BPDU message to
switch
Port used by designated bridge
to transfer BPDU message to
switch
FOR LAN
Responsible for transferring
BPDU message to local
network segment equipment
Port use by designated bridge
to transfer BPDU message to
local network segment
