Network Topologies – CompTIA A+ 220-801: 2.8

If you’re designing a network, you’ll probably use a number of different topology types. In this video, you’ll learn the advantages and disadvantages of some common network topologies.

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In this video, we’re going to look at a lot of different kinds of network topologies. This is really useful to use when you’re planning a local network, a wide area network, and you’re trying to determine how best to connect these different sites together. This can also be used for troubleshooting purposes. If you know which way the data is flowing, it’s going to help you if you ever run into any problems,

A mesh topology is one where we have multiple links they are going to exactly the same place. You sometimes hear this referred to as a fully-connected network. This provides you with some advantages from a connectivity perspective. You’ve got redundancy and fault tolerance built in.

If you lose a connection, you’ve got multiple links. You can simply use the other connections to get around the problem. And you also have the ability to do load balancing over some of these connections. With multiple links, now you have twice as much bandwidth available to send your data back and forth.

It’s very common to see a meshed network on a wide area network. We see fully meshed and partially meshed networks this way, so that you can connect some sites via multiple connections, some sites to be a single connection. And blend together differences on how you want to be able to connect between point A and point B.

We still see ring technologies used in many places. You usually don’t see it in the local area network any longer. Token ring is when you don’t often see any longer. But if you ever go into the back infrastructure in some of these legacy devices, you may still see token ring equipment powered on and sending data between a couple of devices that have to be there to keep the business running.

Where you commonly see a ring network then is in larger networks. Things like your metropolitan area network and your wide area networks will use rings because you have fault tolerance there. If someone is working on the road and they accidentally break one of those connections, you’ve still got connectivity that you can use to circle around the other direction, because everyone is connected in a single ring.

A bus topology was extremely common to see an early ethernet networks. It’s one we really don’t see much any longer. But it allowed us to take a single coaxial cable and extend it from one end of the building to the other and simply connect everybody into that one piece of coax.

The problem obviously with that is if you have a break anywhere along this connection, then it’s broken for everyone who’s on the network. And you have a connectivity problem at that point.

We don’t see bus networks around much longer. But if you look into the wall connectors, sometimes you’ll see the remnants of an old coax network still sitting in there from the days when we used to use those bus-based ethernet networks.

The vast majority of local area networks use a star topology to be able to communicate. Everyone on the network is out and connected to a single concentrator or switch that might be in the middle. Everyone’s connected into the same device or a series of devices, for redundancy. But you can see it’s a star, because everybody is connected into that central device. Nobody’s really connected directly to one another. This is very common to see in switched ethernet, where everybody’s connected to a very, very large switch in the middle of the building or on the floor of the building and you simply have that one device sitting in the middle of everything.

A hybrid topology is one where we’ve taken multiple types of topologies and we’ve simply combined them together. It’s very common to see this in most environments. You’re almost always going to use multiple topology types to connect your networks. In fact you might have an ethernet network that’s in your core that is a star network but to connect out to your remote sites, you’ve created a mesh wide area network.

Using this combination of topologies allows you a lot of flexibility. And if you’re planning a network, this will be a very, very common way to lay out the structure of your network.