Here's a quick summary of the different types of spending tree and the advantages and disadvantages
of each.
So the original version of spending trees the triple e ed. that one D spending tree.
This is the legacy stented on spending tree that was used when bridges were around.
So it's very old but it's the basis of other versions of spanning tree.
You'll also see the term cease tea or common spanning tree.
This assumes that there is one spending tree instance for the entire bridged network regardless of the
number of lines.
We don't use that today in Cisco environments.
We use a version of Poovey line spending tree or previous t originally Peavey's t only supported SL
previously plus supports ISO and added to that one.
Q But today we often referred to previous D-plus as previous t.
So this is a Cisco enhancement a spending tree that provides a separate Ada to that one D spending tree
instance for every plan.
If you had a 100 villans you would end up having a hundred instances of spanning tree each spanning
tree would have its own route and would do its own calculations in Cisco environments each spending
tree would seem its own PPD use or bridge protocol data units.
So if you had a hundred villans every two seconds a hundred BPT use or sent multiple spending tree tries
to optimize previous t by mapping multiple villans to the same spending tree instance.
So to that one s or multiple spending tree allows you for example to have two spending tree instances
and then split your villans between those instances.
Villines one to one hundred could be associated with instance one villans one or one to two hundred
could be associated with instance to but provides a lot of advantages in that you have two instances
of spending tree rather than two hundred which you would have if you used Peavey's t multiple spreading
tree also has rapid spending tree built into it.
So it converges very quickly rapid spending three or eight to get one w improves convergence over the
1998 version of spanning tree by adding Rolf's to ports and enhancing BPT exchanges.
It To provide for much quicker convergence when compared to traditional spending tree Rapide spending
tree however only supports a single instance of spanning tree.
So all the lands are mapped to that single instance and this is why we have a rapid previous t plus
on Siska switches that allows us to have a 1 spending tree instance pervy LAN but have Reppert convergence
now multiple spending tree has the advantage that you can map multiple villains to a single instance
of spanning tree.
That however only becomes important when you have many villans.
If for example you only have 10 villans in your enterprise Reppert previous t plus works really well
and hence it's the default spending tree on Cisco switches.
You would only necessarily need to use multiple spanning tree if you had hundreds or thousands of lines.
So the default today on most Cisco switches is rapid PVC plus provides rapid convergence and allows
you to configure one spending tree instance pavilion to optimize performance in the videos and this
course I'll show you a campus network where we optimize spending tree by splitting the load tween different
switches.
In other words one switch will be the spending tree root for some villans and another switch will be
the spanning tree route for other villains.