Wide Area Network Characteristics.
Frame, ATM, MPLS, and DMVPN.
Behold the cloud.
When it comes to wide area network connections
you can divide them into two major types.
The first is a point to point connection.
That's literally where you have location one connected directly
to location two over a circuit where it's your circuit,
point to point.
The bandwidth is yours.
If it's not being used, it's sitting there idle.
The connection through the service provider network
is yours.
Everything about it is super personalized.
But the problem with that is, first off,
it costs a little bit more money to get that dedicated
connection all the time.
It's hard for the service provider
as well because they literally have
to take a scalpel to the band with what they have and carve
it out just for you.
The second thing is a point to point
connection isn't as flexible.
Just like I said, point to point.
If you have a whole bunch of locations to bring up,
you have to set up a whole bunch of individual circuits
between those locations.
It's for this reason that service providers came up
with the idea of packet switching.
In a nutshell that means that instead of saying
my focus is on bringing a circuit up
between two connections, service providers
can get down to a packet level.
That means when you have a whole bunch of data
to send from point A to point B, that data can take
all kinds of different paths through the network on a packet
by packet basis.
Likewise with a packet switched network
instead of having individual circuits
and individual connections defined,
dedicated between two locations, you
can have all kinds of locations connect to the same quote
unquote cloud or packet switched network
and then define virtual circuits through that cloud
to connect the sites together.
These are actually known as permanent virtual circuits
or PVCs.
So if I have Arizona over here and it's connecting to Texas
over here, we'll say on this side,
we've got one server that's trying
to communicate to that server, obviously it's
a little lopsided.
Then I can define with the service provider
a PVC directly between those locations with its own level
of bandwidth, with its own level of how the packets are treated
known as quality of service, and that defines the monthly rate
that I pay for that circuit.
Then on the same interface, here's
the big difference between point to point and packet switched,
on the same interface, I can define a second circuit that
then goes from Arizona down to Michigan.
And it has its own speed and its own way
of handling packet treatment and quality of service
and all that kind of stuff.
And I pay my own monthly rate for that one.
That's another permanent virtual circuit
that's defined coming in the same interface.
Have you gotten that?
The same, the same.
That's one of the big differences between this
and a point to point interface, is
every location that I would bring up
with a different point to point circuit
would require a different interface on my router.
So one of the original packet switched networks was actually
known as X.25.
That was the technology they use to define it,
that defined the addressing and the coding
that the different routers would use to communicate together.
Anytime you define a standard you have to have
standard ways of communicating.
And that's what X.25 did.
The problem with X.25 is it was super slow because it
had a ton of error checking.
This is back in the '60s and '70s,
before our lines were as reliable as they are nowadays.
So they had to add a whole bunch of overhead
to the communication to make sure it all got there OK.
Well, as the circuits evolved and became
more and more reliable, X.25 was eventually
replaced with frame relay.
This was almost identical to the X.25 world,
but removed a lot of the error checking.
It also had its own addressing known as data link connection
identifiers.
Essentially these were numbers assigned
to each one of the connections.
Let's say this is number 50 and this is number 20.
So if this side, we'll say it's the happy router out
in Arizona, wants to send data over to the other side,
it would tag it with the correct address, the correct data link
connection identifier.
And every single one of those circuits
would get its own DLCI.
So when we're going to back to Michigan down here,
it would get its own address as well.
Every new site that you would bring up
gets in its own address and is now
able to be communicated with across the cloud.
Now what I'm inadvertently drawing right now
is actually known as a hub and spoke topology.
All of these sites come into the one hub
which happens to be Arizona.
But it doesn't have to be that way.
Let's say that this is Missouri over here,
which physically is actually a lot closer to Michigan.
Well sending all of the data over to Arizona
and then having that route down here to Michigan
might add too much delay.
So we could work with the carrier
to define another permanent virtual circuit that
goes direct between Missouri and Michigan.
Yes, it's going to be more money.
But in the end, it has less delay
and gives us a better quality connection.
Now as time went on, even frame relay
started to hit speed limits.
So the technology was upgraded and replaced by ATM.
I shouldn't say replaced.
It was complemented by ATM.
ATM just found creative ways of upgrading
the speed of the connections.
One of the ways it did that is by dividing
all the data into these small things known as cells.
See previously, when you would communicate between two
different locations you would have different sizes of packets
going between those sites.
Well, ATM said, well, there's too
much processing and overhead to deal with that,
so let's divide them up into all these little tiny 53 byte
cells.
The datalink connection identifier addresses
were replaced by something known as a VPI VCI pair, which
really is the same thing, just a different type of address.
And the technology evolved.
Nowadays even ATM has faded away because everything is
moving into the world of MPLS.
That stands for multi-protocol label switching.
Once again, we switched out the addressing.
Instead of VPI VCI pairs, we now call them
tags, which is a lot easier.
MPLS was super groundbreaking because it went connection
neutral, meaning it kind of rides on top
of whatever sort of connection you want.
For instance, you can have a cloud running ATM technology
and bringing in all these different sites together.
But underneath that, the carrier could
run MPLS, which encapsulates it with this tag neutral system
and makes everything super fast.
This cloud might be frame relay underneath.
It might be ethernet.
It might be all kinds of things.
We don't really care because MPLS kind of swallows it all up
and allows everything to connect to everything.
So when it comes to private site connections,
meaning a behind the scenes cloud
that can bridge your sites together,
MPLS is the modern way, the fastest way,
the most flexible way of doing that in today's world.
Now behind the scenes, it's actually a service provider
technology.
So most of the time on the customer side,
you're not going to have a quote unquote MPLS
connection you bring up.
You'll bring up ethernet or frame relay or ATM.
But behind the scenes, the service provider
uses MPLS to bleed it all together into one big blob.
If you have more information about this a couple of years
ago, I created a video called what is MPLS?
It's on YouTube.
Look at that 203,000 views.
There's obviously a lot of interested people about MPLS.
That will give you a much more focused explanation
just on MPLA technology.
The last method of connecting multiple sites together
that we're going to talk about here is known as DMVPN.
That stands for dynamic multipoint virtual private
network.
You've heard of a VPN before, right?
This is a way that you can privately
end encryptedly connect into your organization
from wherever you are in the world.
You're sitting at home, needing to access the private server
with all the JR files that sits behind the corporate firewall.
Well, from your home laptop or desktop or whatever you got,
you can actually establish a VPN connection
through what is this cloud?
The internet.
Because everybody is connected to the internet.
And it makes it feel as if your computer is
directly plugged into the network over here.
Because technically it is.
It's just, along the way we're encrypting all that data so
if prying eyes in the middle grab that data they
won't be able to interpret it.
Now everything I just said describes perfectly
a VPN connection.
So what's the scoop with dynamic multipoint VPN connections?
Well, you can imagine as offices grow and get added to this,
it becomes more and more complex to keep up
all of these tunnels configured between each
and every one of the sites.
So dynamic multipoint VPNs allow them
to automatically add themselves to this mesh of VPN
connections.
The beauty of this style of connectivity
is it uses the internet.
Everybody has an internet connection
so you don't have to purchase a separate WAN connection.
As the internet becomes more and more of a reliable backbone
where we can count on the level of quality of service
it delivers, this becomes more and more
attractive to a growing business because it saves in a huge way
compared to buying a separate private wide area network
connection in addition to an internet connection
for every single site.
That gives you the characteristics
of packet switched WAN connections.
I hope this has been informative for you
and I'd like to thank you for viewing.