If you've been tasked with creating
some documentation of your network configuration,
you might want to create a physical network map.
This would show us exactly what devices
might be on the network, and it would show the physical cable
connections from one interface to another.
It's also common for people to create
a physical map of where devices might be
installed in a particular rack.
That would allow you to go into a data center,
to a specific rack, and identify exactly the piece of equipment
that's listed in your documentation.
These days, of course, you may be
working with network equipment that isn't physical at all.
It may be virtualized.
Or you may want to provide a higher level view of how
the network connects together.
In those cases, instead of creating a physical network
map, you may want to create a logical network map.
And regardless of the type of map you plan on creating,
you want to use some specialized software to do this.
In Windows, you might want to use Visio.
Mac OS has OmniGraffle.
And there are also, third-party websites
that allow you to create these graphics inside of your browser
itself.
These would be high level views that would show how a Wide Area
Network may be connected.
Or it may show the logical communication
of an application, as it goes from a web server
into middleware, and then, the database back end.
If you're working with a third-party,
it's common to use this logical network
map to show how an application data flow may be working.
Or to see exactly how the network may be laid out
across a large area.
This is a good starting point, and then, you
can work down further, to find more details
in the configuration as the collaboration goes along.
There are many different ways to represent a network
topology in these diagrams.
One network topology type might be the star network.
This is a very common network type
in today's switch networks, where
you have a centralized device--
like a switch-- and all of the devices
are connected directly to that switch.
The switch effectively, sits in the middle,
and everybody else connects to it over these Ethernet links.
Another common topology type is the ring topology,
where all of the devices are connected
to each other in a ring form.
We used have token ring network as very popular local area
networks, but now that those are no longer very common,
you would see ring networks and things
like Metropolitan Area Networks and Wide Area Networks.
It's very common to see these ring networks implemented
as dual-ring networks.
That way if there is a break in the network,
it can loop onto itself for fault tolerance
and maintain the uptime of the entire ring
by providing that loop onto itself.
For even additional fault tolerance,
you may want to consider implementing a mesh network.
This is one that has many different links to be
able to get to the same place.
It might have all of the different locations connected
to every other location.
Or it might be a partial link, whereas some locations are
connected to other locations.
You would commonly implement a mesh network
if you were looking for something that was
redundant and fault tolerant.
Or if you needed to balance load between multiple links.
You often see mesh being used in Wide Area Networks.
Since there are so many opportunities
to have a link go down, you would
have redundancy and a way to route around the problem
using this mesh network topology.
A bus typology is a connection that all other devices
connect to.
Very common use of bus technology
was in early networks, where we would have a single co-ax cable
and connect all devices onto that co-ax cable
so they could communicate to each other.
This was obviously, a very easy network
to implement because you simply used
a single cable that everyone would connect to,
but if you did have a break in that cable,
it would disable the entire network.
One place you might find a modern bus technology
is in your automobile.
This is called a Controller Area Network, or a CAN bus
type of network.
And that's where all of the internal devices
inside of your car are able to connect to this single bus
and communicate between each other.
Although, we don't use cables to communicate over our wireless
networks, there are still some logical network
topologies that we use with our 8.02.11 wireless networks.
One of these is the infrastructure topology.
This is the one that most people are
using when they are communicating with an access
point.
You adjoin an access points network
and then, you're able to communicate
with everyone else who happens to be on that network.
But you don't have to have an access
point to be able to communicate with 8.02.11.
You could have devices communicating directly
with each other, without putting an access point in the middle.
We call this ad hoc networking.
You don't need any additional hardware.
You simply configure both end stations
to communicate to each other over this wireless frequency.
And today's Internet of Things wireless networks
often use mesh networking.
These are individual devices that
are able to discover each other and use each other
as a large cloud of devices.
This allows these devices not only to self-form
into this mesh cloud, they can also self-heal.
If a device is disabled, they can simply
use this large number of devices to route around the problem
and enable communication using a different path.