Common Network Topologies – CompTIA Network+ N10-006 – 1.6


If you’re in the
process of building out a new part of your
network, then you need to understand
exactly the advantages and the disadvantages
of the network topologies that you
may be choosing. And in this video, we’ll
look at a very broad overview of some of the most
popular network topologies that you’ll run into. These will help you a lot
with not just planning, but once the
network is in place, you’ll get an understanding
of exactly where the signal of the
network is flowing and where you might run into
problems with maintaining uptime in certain
parts of the network. When we refer to a
network that has a mesh, then it’s one that has
one or more connections to multiple sites. This may be a fully
meshed network where every site is connected
to every other site. But generally, we have
partially meshed networks so that we can have some sites
with multiple connections to other sites, but perhaps
not to every other location that we have. This is obviously a
good type of topology if you’re worried about uptime
because you have redundancy. If you lose one
link to a site, you can simply use the other link. And since we’re all
meshed together, we can eventually get that data
back to where it needs to go. You might also be able
to do load balancing. You may have one
site at the top, and to be able to
connect down to another you might send traffic
over multiple links simultaneously, taking advantage
of all of these redundant links that you’ve created. It’s very common to see
these on Wide Area Networks since we have very
little control about what’s happening
with the network outside of our buildings. This way we can build multiple
links to a single site, and if we lose one
of those links, we still have the other
as a redundant link because we’ve created this mesh. An older topology style that
you still might run into is a bus topology. This is one where you
effectively have a single cable and everybody is
connecting into that cable. It’s a single bus that everybody
is using and communicating through. This is a very simple network. It’s easy to install. Everybody connects
to a single line, but it is prone to errors. If you lose one link
in the middle of this, it will break this
connection and now suddenly half of
the network can’t see what’s happening on the
other half of the network. Also, if one person was to
inject any type of error signals onto this link, it
is going to affect everybody on that bus. We often think of
ring topologies as being those older
style of networks. When we think back to
the older token ring networks for instance. And although we don’t see
token ring networks around much any longer, we
still use ring topologies for our Wide Area Networks. A good example of this would
be something like SONET, where you can build a
redundant ring SONET network in a geographical area. The SONET networks
work by sending exactly the same information
down both sides of the ring. So if you do have a break
anywhere along the way, that information
will be able to make its way by going the other
direction on the ring. If you’re connecting to an
ethernet network right now, you’re probably connected
to a star topology. A star topology is one where
all devices are connected through a device in the middle. Gives it this look
of a star because you have this central device. And on an ethernet
network, this might be a switch whether you’re
using a connection in your home or home office, or whether
you’re in the largest topology in the biggest
companies in the world, they’re all connecting
back to some central switch and have this star
topology in place. A hybrid network is
when we’re combining a lot of these topology
types into one single view. Here’s a good example of having
multiple star topologies. And then we’re connecting
all of these sites together with a ring. We’ve taken different kinds
of topologies, brought them together into something that is
now a hybrid of multiple types. A point-to-point topology is
exactly the way it sounds. You have a device
on one end, you have a device on the
other end, and they’re connected to each other
with nothing in the middle. We see this often with
Wide Area Network links that are a little bit older
like our T-1 or E-1 connections. These are point-to-point Wide
Area Network connections. You may be connecting
buildings together. There may be a single
strand of fiber or copper between the buildings. You might also consider that
a point-to-point connection. The important thing is that
one device is connected to the other device, and there’s
really nothing in the middle. There’s a single
point-to-point between them. Another popular
networking topology is the point-to-multipoint. If you’re on a wireless
network right now, it’s probably something like
a point-to-multipoint network. If you’re using something
like this wireless network, a point-to-multipoint
doesn’t necessarily imply that everybody can
talk to everyone else. It’s really that everybody is
talking to one central device. Most wireless
networks will allow you to talk to other
devices on the network, but some wireless
networks are configured to not allow these wireless
devices to communicate with each other. They can only talk to the center
with this point-to-multipoint topology. Let’s move away from a pure
network topology conversation and talk about more of
the way that applications are architected. In this particular
diagram, we’re showing a client-server
application. This is where the clients are
talking to a central server. Your client might be
a laptop, or a tablet, or a desktop workstation. And to be able to
use this application, everybody talks back
to a central server to be able to perform
these functions. The clients do not
talk to each other, so there’s no client-to-client
communication. And one of the advantages
of doing it this way is that you have
performance advantages because your
server’s really going to determine the performance
of the application. And it’s easy to
administer because you go to one place on the server to
be able to administer this app. This also means
that you’re going to have a little bit higher
cost because this server needs to be strong enough
to support all of these separate clients that
are using this application. And there’s a bit
more complexity because you need
separate clients that are going to be installed or
running on these end stations. And they all have to communicate
across a single network to a single set of servers. Another popular
application type is the peer-to-peer application. In this case, there’s no
central server at all. The different clients
are all communicating between each other to
perform whatever steps they need for this application. Every device is able to
talk to every other device on a peer-to-peer network. This is obviously easy to deploy
since everybody’s probably on the network already, and they
can communicate to each other. And there’s a lower
cost because you don’t have a central
server that has to be built and administered. The disadvantages here
are that it’s much more difficult to administer. There’s no central point
for the application. So now you are effectively
administering this application on every single desktop. You also have to be very
careful about security since every device becomes
both a client and a server in a peer-to-peer network. You have to make sure
everybody is up to date with all of the security
pieces they need and that you’re able to keep
that data as safe as possible.

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