Network Topologies - N10-008 CompTIA Network+ : 1.2

Summary

This video explains the various types of network topologies used in designing, building, and troubleshooting networks. It covers common topologies like star, ring, bus, and mesh, highlighting their applications in both local and wide area networks. The importance of redundancy, fault tolerance, and load balancing in modern networks is discussed. Additionally, it explores hybrid networks that combine multiple topologies, as well as wireless networking options such as ad hoc and infrastructure modes, and the growing use of mesh networks for Internet of Things (IoT) devices.

Takeaways

• 🔍 Understanding network topology is essential for designing, building, or troubleshooting networks.
• ⭐ The star topology, also called hub-and-spoke, is one of the most common topologies, where devices connect to a central hub.
• 🔄 Ring topology, though rarely used in local networks, is popular for wide area networks (WAN) because it provides redundancy by allowing data to reroute if a connection fails.
• 📡 Bus topology was used in early Ethernet networks, but is now largely outdated due to its vulnerability to single-point failures.
• 🚗 Modern cars use CAN bus networks to connect sensors and controllers, improving vehicle safety.
• 🕸️ Mesh networks create multiple connections between devices or sites, offering redundancy and load balancing by utilizing alternative pathways if one link fails.
• 🔀 Hybrid networks combine different topologies, such as a star topology for local networks and a ring topology for wide area networks.
• 📶 Wireless networks often use infrastructure mode, where devices connect through an access point, or ad hoc mode for direct device-to-device communication.
• 🌐 IoT devices often rely on wireless mesh networks, where devices communicate with one another to create an interconnected, self-healing network.
• 🔧 Redundant and fault-tolerant design in mesh networks ensures continuous operation even if some network connections fail.

Q & A

What is the purpose of understanding network topologies in design and troubleshooting?

Understanding network topologies is essential for visualizing data flow, planning new networks, and troubleshooting issues. It helps identify how traffic moves between points and where problems might occur.

What is a star topology and why is it commonly used?

A star topology connects all devices to a central hub, often an ethernet switch. It is widely used in networks of all sizes because it provides an organized structure where devices don't connect directly to each other but instead communicate through the central hub.

How does a ring topology work, and where is it most commonly used?

A ring topology connects devices in a circular structure, allowing data to flow in one direction. It's most commonly used in wide area networks (WAN) and metropolitan area networks (MAN) due to its redundancy, as traffic can loop back if a connection is severed.

Why did early ethernet networks move away from using bus topology?

Bus topology was phased out in early ethernet networks because a single break in the cable could disconnect the entire network. The lack of fault tolerance made it less reliable for local area networks (LAN).

What are CAN bus connections, and where are they typically found?

CAN (Controller Area Network) bus connections are used in modern automobiles to connect sensors and controllers, enabling safer and more efficient communication between the vehicle's systems.

What is a mesh topology, and why is it beneficial?

Mesh topology connects multiple devices or sites, creating multiple pathways between them. This provides redundancy and fault tolerance, ensuring that if one connection fails, traffic can be rerouted through another connection.

What is a hybrid network topology?

A hybrid network combines multiple types of topologies. For example, a local network might use a star topology, while connecting to other sites through a ring topology over a wide area network (WAN).

How do wireless networks typically function with access points?

In wireless networks, devices usually communicate through an access point, creating an infrastructure connection. This is the most common setup for wireless networks.

What is ad hoc networking in wireless communications?

Ad hoc networking allows two devices to connect directly to each other without the need for an access point or other wireless infrastructure.

How do mesh networks work with Internet of Things (IoT) devices?

Mesh networks allow IoT devices to communicate with each other directly, even over long distances. If one device goes offline, the mesh network self-heals and adjusts, maintaining communication among the remaining devices.

Outlines

00:00

🌟 Understanding Network Topologies: The Star Topology

This paragraph explains the concept of network topologies, focusing on the star topology. A star topology is common across various network sizes, where all devices connect back to a central hub, such as an Ethernet switch. The paragraph also touches on the usefulness of understanding topologies when designing or troubleshooting a network, as it helps in visualizing data flow and resolving issues. The star topology is highlighted as a key structure found in most modern networks.

05:01

🔄 The Ring Topology: Redundancy in Wide Area Networks

Here, the focus shifts to the ring topology, which is less common in local area networks but frequently used in wide area and metropolitan area networks. The paragraph discusses the ability of ring topologies to provide redundancy. In cases where a connection is severed, the network can loop back traffic in the opposite direction, maintaining data flow. The paragraph also contrasts older token ring technologies with modern uses of the ring topology in larger network infrastructures.

🔌 The Bus Topology: From Ethernet to CAN Bus in Automobiles

This section discusses the bus topology, which was used in early Ethernet networks, where a single coaxial cable ran through the space, connecting devices. A key disadvantage of bus networks is that a single cable break can disrupt the entire network. Despite this, bus topologies are still used in modern applications, such as in automobiles with CAN bus networks, where sensors and controllers communicate for safety features in vehicles.

🌐 Mesh Networks: Ensuring Redundancy and Fault Tolerance

The mesh topology is introduced as a structure where multiple devices or sites are interconnected through multiple links. This setup ensures redundancy, fault tolerance, and load balancing across the network. Mesh networks are commonly found in wide area networks to maintain connections even if one link fails. The redundancy helps in avoiding downtime, allowing traffic to reroute through alternative connections.

🔀 Hybrid Networks: Combining Topologies for Enhanced Connectivity

This paragraph introduces hybrid networks, where multiple topology types are used together. An example provided is a combination of a star topology for local connections with a ring topology for wide area network communication. Hybrid networks allow for greater flexibility and efficiency in designing complex networks that meet diverse connectivity needs across different locations.

📶 Wireless Networks: Infrastructure, Ad Hoc, and IoT Mesh

The paragraph explains different wireless communication methods. In infrastructure networks, devices connect through an access point, whereas ad hoc networks allow direct device-to-device communication without an access point. It also discusses the role of mesh networks in IoT (Internet of Things) devices, enabling multiple devices, like smart home systems, to communicate simultaneously. Mesh networks are praised for their ability to self-heal, automatically adapting when devices are added or removed.

Keywords

💡Network Topology

Network topology refers to the layout or structure of a network, describing how different devices or nodes are interconnected. In the video, the narrator explains that understanding network topologies is essential for designing, building, and troubleshooting networks, as they help visualize data flow and troubleshoot problems.

💡Star Topology

A star topology is a type of network where all devices are connected to a central hub or switch, creating a star-like configuration. The video highlights this as one of the most common topologies, used in switched Ethernet networks where devices communicate through a central switch, rather than directly with each other.

💡Ring Topology

In a ring topology, devices are connected in a circular format, and data travels in one or both directions around the ring. The video explains that while this topology is not commonly used in local area networks (LANs), it is still prevalent in wide area networks (WANs), especially for its ability to provide redundancy by rerouting data if part of the ring is damaged.

💡Bus Topology

Bus topology is a network configuration where all devices are connected to a single central cable, called a bus. The video mentions that this was a common setup in early Ethernet networks, but it is prone to network failure if the central cable is damaged, which is why it is no longer widely used. However, bus topologies are still found in modern systems, such as in automobiles using CAN bus connections.

💡Mesh Topology

Mesh topology is a network where devices are interconnected with multiple pathways, allowing for redundancy and load balancing. The video describes this topology as useful for creating fault tolerance, especially in WANs, because if one link fails, data can be rerouted through alternative connections.

💡Redundancy

Redundancy in networking refers to having multiple pathways or backups to ensure continued operation if a part of the network fails. The video emphasizes redundancy in ring and mesh topologies, explaining that if a connection is severed, traffic can be rerouted to maintain network uptime and prevent data loss.

💡Wide Area Network (WAN)

A Wide Area Network (WAN) is a network that spans a large geographical area, often connecting multiple local area networks (LANs). The video discusses how WANs frequently use ring and mesh topologies to provide redundancy and maintain connectivity between distant sites.

💡Ad Hoc Network

An ad hoc network is a type of wireless network where devices communicate directly with each other without the need for a central access point. In the video, this concept is explained in the context of wireless communication, where two devices can connect directly if no access point is available.

💡Hybrid Network

A hybrid network is a combination of different network topologies. The video explains that hybrid networks are common when connecting different types of networks together, such as using a star topology for a local area network and a ring topology for wide area connections, blending their strengths.

💡Controller Area Network (CAN)

A Controller Area Network (CAN) is a bus topology used in automobiles to connect various sensors and control systems. The video mentions CAN buses as a modern example of bus topology, explaining how they enable communication between different components in cars to ensure safety and efficiency.

Highlights

Understanding network topology is crucial for designing, building, and troubleshooting networks.

Star topology, also known as hub-and-spoke, is one of the most popular network topologies.

In a star topology, devices connect to a central hub, such as an Ethernet switch, rather than directly to each other.

Ring topology is often used in wide area networks (WANs) for redundancy, where traffic can loop back in case of a connection failure.

Ring networks are useful for maintaining uptime by rerouting traffic in the event of a severed connection.

Bus topology, used in early Ethernet networks, features a single cable, but a single break in the cable can disrupt the entire network.

Modern vehicles use bus topology, specifically controller area network (CAN) buses, to connect sensors and controllers for safety.

Mesh topology allows multiple devices to connect with redundant paths, enhancing fault tolerance and load balancing.

Mesh networks are common in wide area networks, providing primary and backup connections between sites.

Hybrid networks combine different topology types, such as star and ring, to create more complex and versatile networks.

Wireless networks using access points operate in infrastructure mode, the most common wireless setup.

Ad hoc wireless networks enable direct communication between two devices without an access point.

IoT devices often use mesh wireless networks, allowing intercommunication between devices, even when far apart.

Mesh networks for IoT can self-heal, automatically rerouting traffic if a device is turned off or disconnected.

Understanding different topologies helps optimize network design and ensure reliability, redundancy, and fault tolerance.

Transcripts

When you're designing, building or troubleshooting a network,

you'll be using a network topology

type that can vary depending on the technology you're using.

If you're looking to understand the way the data is flowing

or you want to plan to create a new type of network,

then it's useful to understand what these topologies might be.

This is also useful during the troubleshooting process,

because you'll know exactly what flow

the traffic takes to get between point A and point B.

One of the most popular types of topologies

is the star topology.

You might also hear this referred to as a hub

and spoke, where the hub is in the middle

and the spokes are along the outside.

This is a topology that you'll find on

almost any network regardless of the size of the network.

And you'll also find that most devices are connecting back

to the central hub of the star.

For example, a switched ethernet network

has the ethernet switch in the middle of the star.

And then all of the devices run directly back

to this particular switch.

They're not connecting to each other.

They're instead connecting back to the central switch

in this star topology.

Although we don't often see a ring topology used

on our local area networks, it's still

a topology type that's used quite often for wide area

networks.

So although many people will remember the older token ring

technologies that we used to run inside of our local area

networks, we don't generally find those ring networks

any longer.

But if you're connecting over a metropolitan area

network or a wide area network, we

use ring networks extensively.

It's not because a ring technology somehow

lends itself to work better over a wide area network.

It's because we can create additional redundancy

using the ring topology.

For example, a very common way to send traffic

over a ring network is to have the traffic simply go

in a circle.

Now if we're on this wide area network

and there's construction going on

and someone happens to sever a fiber connection that's

being used for this metropolitan area network,

then we're not going to be able to send that traffic

through the rest of that ring.

But the devices that are on either side

of that severed link recognize that traffic

is no longer able to traverse that connection

and instead will loopback the connection

on those individual endpoints.

So instead of having data go around a ring,

the data will instead go to as far

as it can around the ring and then

loopback to get to the other side of the ring,

maintaining uptime and availability even in the case

where part of that ring may be severed.

Early types of ethernet networks were not switched ethernet,

but were instead run over coax.

And this coax was quite simply a cable

that was run down the middle of the room very similar

to this cable.

This is a bus network.

And although it was commonly used

on those early ethernet networks,

we can still find modern networks

that use the same bus topology.

One problem with bus networks is that it is a single cable that

is running either through the walls

or down the center of the room.

And if we happen to have a break in this cable,

you can see immediately that it would suddenly

segment the network into different pieces.

Or in some cases, cause no data to be

transferred across the network.

That's one of the reasons we moved away from bus networks

for our local area networks, because one single disconnect

could cause an outage for everybody else on the network.

In our modern automobiles, we have bus networks

that we use extensively.

These are controller area network buses, or CAN bus

connections.

And they're used to connect all of the different sensors

and controllers inside of our automobiles

to be able to make all of our cars much safer

to drive on the roads.

Another popular topology, especially in larger networks,

is to create a mesh between devices

or a mesh between sites.

We may have devices that are connected

in different locations.

And we might want to connect them all together.

But instead of having a single connection

to a particular site, we may want

to create multiple connections to mesh these together.

That way if we do lose any one of these network links,

we're able to work around that problem by simply using one

of the redundant connections.

You'll commonly use this type of mesh design

if you're creating redundancy or fault tolerance

or perhaps you're designing a load balance network

and you can use different parts of the network

to share that load.

Probably the most common place to find a wired mesh network

is over a wide area network where

you can create multiple links to other sites

so that you can have a primary connection from one

site to the other and then a backup or secondary connection

that you can use if you run into problems.

When you start combining these different typologies together,

you create a hybrid network.

A hybrid network is more than one of these topology types

all working together.

For example, you might have three remote sites

all connecting devices together using a switched ethernet

or star network.

And then you may be connecting those together

over a wide area network that uses a ring topology.

If you're using a wireless network,

you may be communicating in a number of different ways.

If you're using an access point, you're

probably communicating over an infrastructure connection.

This means that all of the devices on your network

are communicating through an access point.

This is probably the most common way

to use wireless connections, but it's not the only way

to communicate over a wireless link.

If you just have two devices and there's no access point

that you can use, you can connect directly

from one device to another using ad hoc networking.

You don't need an access point or any other type

of wireless infrastructure.

You simply have one device communicate directly

to another device over this wireless connection.

And if you've added internet of things devices, which

are commonly wireless devices that control our lights,

our door locks, or the air conditioning systems, then

you're probably using a mesh network

where all of these devices can communicate

to all the other devices simultaneously

to create an interconnected mesh of communication between all

of these IoT devices.

One of the advantages of these mesh

wireless networks is that it allows

many devices to communicate to each other

even if those devices are very far apart from each other.

This also allows the mesh network to self-heal.

So if you turn off one of those IoT devices,

the remaining devices will self-heal and redesign

themselves into a mesh network that

will allow them to continue the communication.