Now rapid spending tree is backward compatible with 82 to 1 D.
And in the same way Rapid PvZ T is compatible with PvP on switch three.
These ports were converging quickly because we're using rapid spanning tree between switch one, two
and three, but the links to switch four are still using PVS.
DT So what you'll notice is it takes longer for those lengths to converge.
Show Spending Tree, as an example, shows me that the ports are now forwarding, but they've taken
a lot longer to converge than they would with rapid pivot.
So once again, on interface gigabit zero one, I'll know shut the port show spanning tree.
We can already see that gigabit zero one is the root port and is forwarding and gigabit is zero zero
is an alternate port and is blocking.
However, other ports such as Gigabyte zero two and zero three are still learning.
So it's going to take time for these ports to move to the forwarding state.
You can see they've now moved to the forwarding state, but that's because there is an older version
of spending tree negotiated between switch three and switch four.
Switch three once again is using.
Rapid pivot switch for, however.
He's using per vlan spanning tree not rapid PV ist.
So I triple e is shown in the output whereas once again on switch three it's rapid PV ist, so there
is backward compatibility between rapid PV ist and PV ist, but the convergence will be slow between
rapid PV ist and PV ist because of backward compatibility and within the PV ist part of your network.
Let's have a look at the capture.
So this is on switch three as advertised to the hub.
And what you can see here is that the protocol used is spanning tree, not rapid, spanning tree.
And that's because switch three has negotiated to use spanning tree with switch for not rapid spanning
tree.
So in the output once again it's spanning tree protocol not rapid spanning tree protocol.
Path cost.
Root identify and bridge identify are shown here, but it's negotiated to use the older version of Spanning
Tree.
Even though this document is old, it provides a great explanation of rapid spanning tree or ADA two
or one W and multiple spanning tree or 82.1 se.
You can find this document as part of the course, or you can search in Google as an example for the
Cisco AVID Network infrastructure.
This document explains the evolution of spending tree and how spending tree has existed for a long time
in an unchanged format, but has been enhanced through the use of rapid spending tree and multiple spending
tree.
Ed one D once again is the initial version of spending tree and was designed to stop loops in, switch
to or bridged networks.
It was very difficult to get foster convergence with ADA 2 to 1 D.
One of the problems with Ada through one D is that it uses timers.
Supports go from blocking to listening to learning to forwarding.
And that process can take 50 seconds.
When a port comes up as an example, it goes from listening to learning to forwarding, which takes
30 seconds.
Now Cisco enhanced ed one D in the 1990s by introducing uplink Fost Backbone Fost and Port Fost for
the CCNA course today.
You don't need to know about uplink Fost or Backbone Fost.
You can just ignore those.
The important one to remember is Port Fost or Edge ports, which are ports connected to end user devices
such as PCs or servers that transition immediately to the forwarding state.
The Triple E incorporated most of these concepts into two standards.
Rapid spending tree and multiple spending tree.
With these protocols, convergence timers were a lot quicker.
Cisco have taken those protocols and enhanced PVS.
T So today we have rapid pivot on Cisco switches.
So as an example on the switch, we can type spanning tree mode and we can specify rapid PVS, PT or
MST.
The industry standard version of Rapid Spanning Tree only has one route in the entire topology, whereas
a rapid PVS PT gives you a route on a per VLAN basis.
So it's a lot better than pure, rapid, spanning tree or edited or one w multiple spanning tree doesn't
give you a route per VLAN, but it gives you the ability to associate multiple VLANs to a spanning tree
route.
So you could say in a campus network as an example, that VLANs 1 to 100 have switched one as they route,
but VLANs 101 to 200 have switched to as they route.