So how is this rapid convergence or rapid transition to forwarding state accomplished in a 2 to 1 W
or rapid spanning tree?
This is one of the most important features introduced in rapid spanning tree.
The difference is that a legacy spanning tree.
In other words, the legacy spanning tree algorithm passively waited for the network to converge before
moving a port into the forwarding state.
Achieving foster convergence was a matter of tuning the conservative default parameters of forward delay
and max age timers.
So in the past you would try and manipulate these timers to get spanning tree to converge quicker.
But this often resulted in the sacrificing of network stability.
Rapid spanning tree is able to actively confirm that a port can safely transition to forwarding without
relying on any timer configuration.
That's the big difference.
It doesn't rely on timers.
There is a negotiation between the switches on point to point lengths to allow them to converge quicker.
So there's a feedback mechanism that operates between rapid spanning tree compliant bridges.
To achieve foster convergence, you need to configure edge ports and links between switches need to
become point to point lengths.
Now an edge port is essentially the same as port first ports.
They transition immediately to the forwarding state.
This is to allow in stations to skip the listening and learning stages in spanning tree convergence
and edge port also does not generate topology changes when its link toggles.
So in other words, when a link goes down or comes up and it's configured as an edge port or a port
first port, it doesn't cause the network topology to recalculate.
Unlike Port Foster, though, and each port that receives a beep due immediately loses its edge port
status and becomes a normal spanning report that is a built in security mechanism to stop someone accidentally
plugging in a switch or a hub into a port first port and causing a loop in Cisco's implementation.
The port first command is used for edge port configuration, thus making the transition to rapid spanning
tree simpler.
In a separate video, I'll show you the configuration and testing of Port First Ports.
I've already demonstrated how to set up a point to point link.
This is automatically determined on physical switches using the duplex of a port.
A port.
Operating in full duplex is assumed to be point to point.
Half duplex is considered to be a shared port on switch to in this topology.
Gigabit is zero.
Zero is a point to point link gigabit zero one is a shared port because it's connected to a hub.
It's a half duplex connection.
In today's networks, most links are operating in full duplex mode and are therefore treated as point
to point links between switches in rapid spanning tree.