Let's talk about another important networking topic, and it is none other than networking, topologies
and modern types of networks.
This is pretty easy material and I'm betting you know it already, so I won't belabor any of these points.
Well, let's talk about the classic bus topology.
In a bus topology, you have nodes connecting directly to a media and they are all able to use that
media.
This very simplified topology is certainly how Ethernet began its life when we had the twisted pair
and we would do a bus topology.
And one of the reasons this topology was famous and one of the famous components about it was we would
often talk about Terminators because how this worked was the signal might just bounce around on the
cable forever.
So to avoid that, you would have a Terminator or Terminators at each end that would stop the signal
from endlessly looping.
The interesting thing about the bus topology when compared to the popular topologies of networks today,
is that there was no intermediate device that was needed that was doing any kind of a function.
When we think of networks now, we always think of a hub or a transparent switch as providing functionality
that makes the network a reality.
But with the bus network, there was no intermediate device.
Now I'm talking in terms of real old legacy technology here, but one of the things that we need to
realize is the bus is still with us today.
And where you might see this oftentimes is inside of a PC or inside of a router, you might have particular
components that are communicating using the bus stop ology.
Another hugely popular topology is the Star network, and this is what we see in so many networks today.
This is where there is an intermediate device, often shown in diagrams in the center that is going
to be proliferating the traffic communications.
It used to be a hub in today's environments.
It's now a more intelligent layer to, at the very least, transparent switch.
You might even have a fancier switch, of course, that is multilayer, that has the ability to route
and switch and do firewalls and do advanced analysis of packets.
So switches get very sophisticated.
They might be simple layer two switches, relatively inexpensive, or they may be more expensive, much
fancier switches.
But notice the STAR Network does have some intermediate device, like a hub or a switch that is helping
out.
In fact, what we really tend to describe these networks as today is extended star networks, which
means that you have a star that connects to another star that connects to another star, and it makes
this huge like snowflake type design.
So pretty cool.
The star in the extended star are what we see today.
Ring networks are still out there today, though we often see these inside of components like the bus
network or will see these in wide area networking in the ring topology.
Notice there was never a need for termination, but what there was often times done in ring topologies
was some kind of a token or beacon that the communicator would use.
And then when they were done communicating, someone else could grab that beacon or token.
The technology of token ring was where we saw this implemented.
That was a ring type of topology and there was a token that you needed to possess in order to communicate.
While that's legacy technology, you won't find anymore except for in technology museums today, like
I said, you might still find ring type topologies in bands.
We can't forget the mesh network.
Maybe it's a partial mesh where you don't have all nodes connected to every other node.
Or maybe it's the full mesh where all nodes are connecting to all other nodes like shown on the left
here in this diagram.
And that starts to get really expensive and can get much more complex.
But it has the advantage, of course, that full mesh of being extremely fault tolerant.
By the way, when we talk about the partial mesh, the great example of that is often called the hub
and spoke type design.
Yes, that is a partial mass mesh approach.
Well, what if you have some combination of these in the top?
And we often do, of course.
Well, then technically we'd say it's a hybrid network, and that's very realistic for today.
I just want you to keep in mind, though, you'll often be making logical topology diagrams of your
network and then physical, and those are going to be very different diagrams.
Think about it.
A physical diagram is going to show exactly what physical devices and cables traffic is making its way
through from point A to point B.
A logical diagram might just show what the end user experiences.
So imagine that the end user is like, Oh, I'm sending traffic from this client to this server.
So they see it is just an easy point to point thing.
And then they don't realize the physical diagram has them going through maybe four intermediate devices.
So the physical would show all that detail.
The logical might leave that detail out.
So just keep in mind many different types of diagrams based on these many different types of topologies
we might encounter.
Now we've got to talk about the types of networks, and we know there's the local area network that
we can create, and when we need to send data to a much greater geographic distance will use the wide
area network.
But what about a man?
Sometimes I have C-H or E.H. students that are not familiar with the Metropolitan Area Network.
Yeah, this is when we have typically high speed copper or perhaps longer distance fiber that is being
used to connect facilities that are all within a metropolitan area of each other.
Maybe we have a bunch of buildings downtown and they're connected with real high speed copper.
That's a metropolitan area network.
There's also the wide oh my gosh, wireless local area network.
Right.
Or wi fi local area network.
The wireless LAN.
There may be defined a campus area network, a can.
And this is where it gets a little silly because you're probably going to have one organization or one
entity call their metropolitan area network, a campus area network.
And then you may have another company with the exact same type of network called there's a metropolitan
area network instead of a campus area network.
So a lot of these can be used interchangeably on the wireless local area network, of course, is,
you know, very specific to where we are connecting devices over Wi-Fi for the purposes of sharing data.
And there is no wide geographic distance between them.
An interesting one is the virtual local area network.
We do this on our network switches.
You see, switches right out of the box are great because when you take a transparent switch out of
the box and you connect your devices to it, it immediately starts doing the Mac address learning and
the intelligent forwarding and filtering of frames without you having to get involved.
It just immediately starts doing all of that.
Now what it doesn't do, what this device doesn't do is break up the ports into separate broadcast domains.
So unfortunately, by default, sure, the switch is forwarding and filtering the unicast traffic,
but the switch is flooding out all of the broadcasts.
This is not good.
And think about how many hacker type based attacks are going to be leveraging broadcasting capabilities.
This is a weakness.
The broadcast traffic form in TCP IP, really, and we should minimize the proliferation of broadcast
traffic.
So the switch has the ability to carve itself up into virtual local area networks.
That makes for more and smaller broadcast domains.
And this is a great design for the network.
So we have talked about two topics here, haven't we?
Both the network topologies and also those important types of networks.
Yes, this is another place where we need to make flashcards for you, so we will to help you with these
concepts.
Enjoy.