Free CCNA | Interfaces and Cables | Day 2 | CCNA 200-301 Complete Course

Summary

This comprehensive CCNA course by Jeremy's IT Lab covers networking interfaces and cables, focusing on Ethernet standards and cable types. It explains RJ-45 connectors, UTP cables, and the importance of network protocols. The lesson delves into Ethernet speeds, cable specifications, and the evolution of networking devices, including the necessity of straight-through and crossover cables, and the convenience of Auto MDI-X. It also explores fiber-optic cables, comparing them with UTP and detailing different standards like 1000BASE-LX and 10GBASE. The video concludes with a quiz to reinforce learning, aiming to prepare viewers fully for the CCNA exam.

Takeaways

• 📚 This video is part of a complete CCNA course by Jeremy's IT Lab, offering free educational content to prepare for the Cisco Certified Network Associate exam.
• 🔌 The lesson focuses on network interfaces and cables, explaining how different devices in a network are connected, with a particular emphasis on wired connections before covering wireless later in the course.
• 🖥️ The video introduces the concept of a switch with multiple interfaces, typically used to connect end hosts like PCs and servers, highlighting the 24 10/100/100Base-T ports with Auto-MDIX capability.
• 🔩 The RJ-45 port is the standard for connecting devices to a wired network, using a Registered Jack connector on the end of a copper Ethernet cable.
• 🌐 Ethernet is defined as a collection of network protocols and standards, not a single protocol, with the video concentrating on cabling types as per Ethernet standards.
• 🤝 Network protocols and standards are essential for interoperability between network devices, analogous to a common language facilitating communication.
• 🌀 The video explains the concept of bits and bytes, and how network speeds are measured in bits per second, contrasting it with data storage measured in bytes.
• 📈 The IEEE 802.3 standard defines various Ethernet cable standards, with the video detailing the differences between 10BASE-T, 100BASE-T, 1000BASE-T, and 10GBASE-T.
• 🛰️ Unshielded Twisted Pair (UTP) cables are the most common type of copper cable used in Ethernet, with the twist in the pairs helping to reduce electromagnetic interference.
• 🔄 Full-Duplex transmission allows for data to be sent and received simultaneously over separate wire pairs in Ethernet connections, which is facilitated by the use of specific pin pairs for transmission and reception.
• 🔄 The video clarifies the difference in pin usage between devices like PCs, routers, and switches, and how a crossover cable is used to connect similar devices by reversing the transmit and receive pairs.

Q & A

What is the purpose of the course mentioned in the video?

The purpose of the course is to provide a complete study guide for the Cisco Certified Network Associate (CCNA) exam, covering all necessary topics to pass the exam, and it is offered 100% free.

What is the focus of the second lesson in the CCNA course?

The second lesson focuses on interfaces and cables, specifically how to connect network devices using cables and the basics of wireless connections, which will be covered later in the course.

What does RJ-45 stand for and what is its use?

RJ-45 stands for Registered Jack and it is used for the connector at the end of a copper Ethernet cable, fitting into ports on devices such as computers and switches.

What is Ethernet and why is it important to have standards like it?

Ethernet is a collection of network protocols and standards that define how data is transmitted over a network. It is important to have standards like Ethernet to ensure compatibility and communication between different network devices.

What is the significance of the term 'bits per second' in measuring network speeds?

Bits per second is the unit used to measure the speed of data transmission over a network. It indicates the number of bits (0s or 1s) that can be sent per second, with common multiples including kilobits, megabits, and gigabits per second.

What is the difference between a 'bit' and a 'byte'?

A 'bit' is a binary digit that can be either a 0 or a 1, the smallest unit of data in computing. A 'byte' consists of 8 bits and is a larger unit of data commonly used to measure data storage and transmission sizes.

Why are network protocols necessary for communication between network devices?

Network protocols are necessary because they provide an agreed-upon system of communication between devices, similar to a common language, ensuring that data is transmitted and interpreted correctly between different devices.

What does the term 'Auto MDI-X' refer to and what is its function?

Auto MDI-X refers to a feature in modern networking devices that allows them to automatically detect which pins their neighbor is using to transmit data and adjust their own operations to match, eliminating the need for specific straight-through or crossover cables.

What are the main differences between single-mode and multimode fiber cables?

Single-mode fiber cables have a narrower core and use laser-based transmitters, allowing for longer cable lengths and higher data transmission rates, but they are more expensive. Multimode fiber cables have a wider core, allow multiple angles of light to enter, and are less expensive but support shorter cable lengths.

What is the maximum cable length for twisted pair cables as defined by Ethernet standards?

The maximum cable length for twisted pair cables as defined by Ethernet standards is 100 meters, which is set for performance and technical reasons.

How does a crossover cable differ from a straight-through cable?

A crossover cable differs from a straight-through cable in that it reverses the transmit and receive pairs, connecting pin 1 to pin 3 and pin 2 to pin 6 on the opposite end, allowing devices of the same type to communicate with each other.

What are the advantages and disadvantages of using fiber-optic cables compared to UTP cables?

Fiber-optic cables offer advantages such as longer transmission distances, immunity to electromagnetic interference, and no signal emission for enhanced security. Disadvantages include higher cost and the need for more expensive SFP ports. UTP cables are cheaper and more common for short-distance connections but are susceptible to EMI and have lower maximum cable lengths.

Outlines

00:00

😀 Introduction to CCNA Course and Network Interfaces

Jeremy's IT Lab presents a comprehensive CCNA course aimed at covering all exam requirements for free. The video includes a quiz for knowledge reinforcement and suggests using Anki flashcards for better retention. The focus of this lesson is on network interfaces and cables, explaining how devices in a network are connected. The instructor introduces the concept of switches with multiple interfaces and the importance of understanding the technical terms associated with them, such as RJ-45 ports and Ethernet standards.

05:00

🔌 Understanding Ethernet Cables and Network Protocols

This section delves into the specifics of Ethernet, emphasizing it as a collection of network protocols and standards rather than a single protocol. The importance of network protocols is illustrated with an analogy of communication between people speaking different languages, highlighting the need for a common system of communication. The summary also covers the physical aspects of network connections, including the types of cables and connectors used, and the concept of bits and bytes in data transmission, with a focus on the measurement of network speeds in bits per second.

10:01

🛠️ Exploring Copper Ethernet Cable Standards and UTP Cables

The script provides an in-depth look at the IEEE 802.3 standard for Ethernet cables, detailing the various speeds and their corresponding names and maximum cable lengths. The explanation includes the difference between shielded and unshielded twisted pair (UTP) cables, the function of the RJ-45 connector, and the pin usage for different Ethernet standards. The summary also touches on the concept of full-duplex transmission, allowing devices to send and receive data simultaneously without collision.

15:01

🔄 The Function of Crossover and Straight-Through Cables

This paragraph explains the difference between crossover and straight-through cables, their use in connecting devices such as routers, switches, and PCs, and the potential issues that may arise when devices transmit and receive data on the same pin pairs. The script clarifies the functionality of network interface cards in various devices and how they relate to the use of crossover cables. It also introduces the concept of Auto MDI-X, a feature that simplifies cable requirements by allowing devices to automatically adjust their transmit and receive functions.

20:07

🚀 Advancements in Ethernet: Gigabit and 10 Gigabit Ethernet

The script discusses the higher-speed Ethernet standards, 1000BASE-T and 10GBASE-T, which utilize all eight wires in the RJ-45 connector and operate on a bidirectional basis, meaning each wire pair can transmit and receive data. This section highlights the evolution of Ethernet technology, moving from the use of two pairs of wires to all four pairs, and the implications for network speed and performance.

25:07

🌐 Fiber Optic Cables: The Future of Networking

This section introduces fiber optic cables as a superior alternative to copper UTP cables, especially for longer distances and higher security. The explanation covers the basic structure of fiber optic cables, the difference between single-mode and multimode fibers, and their respective characteristics. The summary also includes a comparison of various fiber optic standards, such as 1000BASE-LX, 10GBASE-SR, 10GBASE-LR, and 10GBASE-ER, detailing their maximum cable lengths and the types of fiber they use.

30:10

🔍 Comparing UTP and Fiber Optic Cables for Network Infrastructure

The script provides a comparative analysis of UTP and fiber optic cables, discussing their cost, maximum cable distances, vulnerability to electromagnetic interference, and security implications. It outlines the scenarios where each type of cable would be the most appropriate choice, considering factors such as distance and cost.

35:11

📝 Concluding the Lesson with a Quiz and Additional Resources

The final part of the script wraps up the lesson with a quiz to reinforce the viewer's understanding of the material covered, including questions about cable types, Ethernet standards, and networking scenarios. The instructor also provides supplementary materials such as flashcards and a practice lab to aid in learning and retention. The script concludes with a call to action for viewers to support the channel through subscriptions, likes, comments, shares, and donations.

Keywords

💡CCNA

CCNA stands for Cisco Certified Network Associate, which is a certification program for networking professionals. It is the main theme of the video as it is a course designed to prepare individuals to pass the CCNA exam. The script mentions that the course includes all the necessary material to pass the exam, indicating the comprehensive nature of the content covered.

💡Interface

In the context of networking, an interface refers to a point where different networks or devices connect. The script discusses interfaces on a switch, which are the ports used to connect end hosts like PCs and servers. It is a fundamental concept in understanding how devices are interconnected in a network.

💡Cables

Cables are physical connections used to link network devices. The script focuses on different types of cables, such as Ethernet cables with RJ-45 connectors, and their roles in establishing network connections. It is a key component in the lesson, as it explains how devices are physically connected in a network.

💡Ethernet

Ethernet is a set of network protocols and standards for wired connections. The script explains that Ethernet encompasses various standards for cabling, which are crucial for ensuring compatibility and performance in network connections. It is a central concept in the video as it underpins the discussion of cable types and standards.

💡RJ-45

RJ-45 is a type of connector used for Ethernet cables. The script describes RJ-45 ports on devices like switches and the RJ-45 connectors on the ends of cables. It is a key term because it is the standard connector type for most wired network connections discussed in the video.

💡Network Protocols

Network protocols are the rules and standards that govern the communication between network devices. The script uses the analogy of people speaking different languages to explain the importance of protocols in facilitating communication. They are essential for the functioning of networks and are a key concept in the video's educational content.

💡Speed

In networking, speed refers to the rate of data transmission and is measured in bits per second. The script discusses various speed measurements, such as kilobits, megabits, and gigabits per second, to explain how fast data can be sent over a network connection. It is a critical concept for understanding network performance.

💡IEEE 802.3

IEEE 802.3 is the standard that defines Ethernet technologies, including cable types and speeds. The script provides a table of IEEE standards for copper Ethernet cables, illustrating the importance of these standards in determining cable capabilities and performance. It is a fundamental concept for understanding the technical specifications of network cables.

💡UTP Cable

UTP stands for Unshielded Twisted Pair, which is a type of cable used in Ethernet connections. The script explains that UTP cables consist of pairs of twisted wires without a metallic shield, making them more susceptible to interference but also more common and cost-effective. It is a key term in the discussion of copper cabling used in networks.

💡Full-Duplex Transmission

Full-Duplex Transmission is a method of data transfer where data can be sent and received simultaneously over a communication channel. The script uses this term to describe how modern Ethernet standards allow for simultaneous transmission in both directions, which is essential for understanding the efficiency of network communication.

💡Auto MDI-X

Auto MDI-X is a feature that allows network devices to automatically detect and adjust for the type of cable connection (straight-through or crossover). The script explains that this feature eliminates the need to use specific types of cables for certain connections, making networking more flexible and convenient. It is an important concept in the video as it relates to modern networking practices.

💡Fiber Optic Cable

Fiber optic cables are a type of cable that uses light to transmit data over glass or plastic fibers. The script contrasts fiber optic cables with copper UTP cables, highlighting their advantages such as longer transmission distances and higher resistance to interference. It is a key term in the video's discussion of alternative networking technologies.

💡SFP Transceiver

SFP stands for Small Form-factor Pluggable, which is a type of transceiver used to connect fiber optic cables to networking devices. The script mentions SFP transceivers as a component that can be inserted into certain network device ports to enable fiber optic connections. It is an important term for understanding the hardware used in fiber optic networking.

💡Single-mode Fiber

Single-mode fiber is a type of fiber optic cable that has a narrow core and allows light to travel in a single path or mode. The script explains that single-mode fiber supports longer cable lengths and is more expensive than multimode fiber. It is a key term in the video's comparison of different fiber optic cable types.

💡Multimode Fiber

Multimode fiber is another type of fiber optic cable with a wider core that allows multiple paths or modes for light to travel. The script describes multimode fiber as being less expensive and suitable for shorter distances compared to single-mode fiber. It is an important term in understanding the options available for fiber optic cabling.

Highlights

The course is a comprehensive, free study resource for CCNA aspirants.

A quiz is provided at the end to test knowledge retention from the video.

Anki flashcards are recommended for memorization and are linked in the description.

Interfaces and cables are the focus of the second lesson, with a detailed look at switch ports.

The explanation of 10/100/100Base-T ports and Auto-MDIX is provided for technical understanding.

RJ-45 ports and connectors are introduced as standard for wired network connections.

Ethernet is defined as a collection of network protocols and standards, not a single protocol.

The necessity of network protocols and standards for communication between devices is explained.

Data transmission speeds are measured in bits per second, not bytes, with explanations of bit and byte.

A detailed breakdown of Ethernet cable standards under the IEEE 802.3 standard is provided.

Unshielded Twisted Pair (UTP) cables are discussed, including their construction and vulnerability to EMI.

Pin usage for Ethernet standards 10BASE-T and 100BASE-T is detailed, explaining full-duplex transmission.

The function of straight-through and crossover cables in connecting network devices is clarified.

Auto MDI-X feature in modern devices is explained, which eliminates the need for crossover cables.

Gigabit and 10 Gigabit Ethernet use all 8 wires in the cable, with each pair being bidirectional.

Fiber-optic cables are introduced as superior technology for longer distances and no EMI vulnerability.

Single-mode and multimode fiber cables are compared in terms of cost, distance, and light transmission methods.

Fiber-optic standards like 1000BASE-LX, 10GBASE-SR, 10GBASE-LR, and 10GBASE-ER are outlined with their specific use cases.

A comparison between UTP and fiber-optic cabling is provided, highlighting their advantages and disadvantages.

Supplementary materials including flashcards and practice labs are mentioned for further learning.

Quiz questions throughout the video reinforce the learning of key concepts covered.

Transcripts

Welcome to my complete CCNA, Cisco Certified Network Associate course.

This is Jeremy’s IT Lab.

This course aims to be a complete course for the CCNA, including everything you need to

pass the exam, all 100% free.

Stay tuned till the end of the video for the quiz to test your knowledge of the material

in this video.

Also, remember to download and use the Anki flashcards with the link in the description.

Let’s get started.

This second lesson is about interfaces and cables.

In the last video we talked about some different kinds of devices you will find in networks.

This lesson will focus on how we connect them, specifically how we connect them with cables.

Wireless connections are also a topic we’ll cover, but that’s for later in the course.

Take a look at this photo.

This is the front of a switch.

Notice the 24 interfaces, also known as ports.

Remember, as we learned in the last lecture, one characteristic of switches is that they

tend to have lots of interfaces to connect end hosts like PCs and servers to.

Now let’s look at that those words above the interfaces.

I’ll zoom in.

10/100/100Base-T ports (1 – 24) – Ports are Auto-MDIX.

Unless you’ve already studied this stuff, you probably have no idea what that means.

Don’t worry, by the end of this video you’ll understand all of this and more.

Now let’s focus on the interfaces themselves.

I’ll zoom in again.

Do you recognize this shape?

If your computer is connected to a wired network, it’s surely using a port like this to connect

to the network.

These are called RJ-45 ports.

RJ stands for Registered Jack, by the way.

Let’s look at the RJ-45 connector at the end of a cable, I’m sure you’ve seen one

before.

These are all cables with RJ-45 connectors.

As you can see there are some variations in design and color, but all of these connectors

would fit into the ports we saw in the previous slide.

The RJ-45 connector is used on the end of a copper Ethernet cable.

There are Ethernet cables which do not use copper wiring as well, but we’ll get to

that later.

First of all though, what is Ethernet?

Ethernet is a collection of network protocols and standards, rather than just a single protocol.

So really Ethernet isn’t one single thing, making it difficult to define exactly what

it is.

For the purpose of this lesson, we will focus on types of cabling as defined by Ethernet

standards.

As said above there are many standards included in Ethernet, but the focus of this lesson

is interfaces and cables, so that’s what we’ll focus on.

However, we will learn other aspects of Ethernet in future lessons.

Now, before we learn about Ethernet cable standards, I want to give a brief explanation

of why we need network protocols and standards.

If two people are talking to each other, and one only speaks English, and the other only

speaks Japanese, there’s not going to be a much, or any, communication between them.

What they need is some agreed upon system of communicating, like a common language between

them.

Network protocols serve that purpose for network devices.

That’s why standards like Ethernet exist.

Since we’re talking about interfaces and cables in this video, here’s a more relevant

example.

If you’re trying to connect to, for example, a network switch, but the maker of the cable

and the maker of the switch haven’t agreed upon the size and shape of the connector and

port, you won’t be able to connect them.

That’s why there are industry standards that all vendors follow, both in terms of

physical standards like connectors and cables like these, as well as logical standards,

like IP, the internet protocol.

Now, connections between devices in a network operate at a set speed.

These speeds are measured in bits per second.

What is a bit?

Well it’s a value represented by either a 0 or a 1.

This binary code is how computers work.

YouTube, this video, your operating system, all of it just a series of 0s and 1s which

your computer interprets.

When communicating across a copper network cable, a variation in the electrical signal

is interpreted by the receiving device as a 0 or a 1.

So, that’s a bit, what’s a byte?

Here we have a series of 8 bits.

8 bits is equal to 1 byte.

Now, speed is measured in bits per second.

Imagine a byte, 8 bits, of data being sent along a wire.

It reaches the neighboring device one bit at a time like this.

It doesn’t operate one byte at a time like this.

So, remember, speed is measured in bits per second, for example kilobits per second, megabits

per second, gigabits per second, and not bytes per second.

Data on a hard drive for example is measured in bytes, however, so remember a Gigabyte

is actually 8 times larger than a gigabit.

So let’s review some of these measurements.

1 kilobit is equal to 1,000 bits.

Add three zeroes to that

And you get 1 megabit, which is 1 million bits.

Add another three zeroes,

And you get one gigabit, or 1 billion bits.

Add another three zeroes to that

and you get one terabit, 1 trillion bits.

You’re not going to see larger units than this when it comes to network speed, and really

you’re not going to see terabits either.

Speeds are always increasing, however, so terabits-per-second speeds may be commonplace

soon enough!

Now, there are further units, here’s a snapshot from wikipedia.

Beyond terabits there are petabits, exabits, zettabits, yottabits, and more.

Don’t worry about memorizing all of these though, you’re not going to see network

speeds like these anytime soon!

Okay, finally lets talk about some Ethernet standards.

These are all defined in the IEEE 802.3 standard.

The IEEE is the institute of electrical and electronics engineers.

You’ll notice all of these Ethernet standards begin with IEEE 802.3.

Let’s take a look.

So, here’s a table of some IEEE standards for copper Ethernet cables.

We’ll also take a look at fiber optic cables later in this lesson, but I decided to split

them up.

We have one for each of the common network cable speeds, 10 megabits per second, 100

megabits per second, 1 gigabit per second, and 10 gigabits per second.

The next column lists the common names.

These are the names we usually use when talking about different networks interfaces, cables,

and their speeds, for example in a work environment.

The next column lists the official IEEE standard in which they are defined.

You would probably never use these names when talking with other network engineers about

a cable, but you should be familiar with them.

This next column lists informal standard names given to each standard.

10 base-T, 100base-T, 1000base-T, and 10gbase-t.

The numbers obviously refer to their speeds.

How about base and T?

Well, base refers to baseband signalling.

That’s totally out of the scope of the CCNA, but just so you know the meaning.

T refers to twisted pair cabling, and we’ll talk about that very soon!.

Finally, the maximum cable length.

Notice that all of them are 100 meters, that’s the maximum length for twisted pair cables

as defined in Ethernet, for performance and technical reasons.

So, that’s a lot of information, but I recommend you memorize these standards.

It may seem difficult, but with the flashcards in the description, it’s actually quite

easy!

So, don’t forget to download and use the flashcards in the description, and also make

your own if you want.

Okay, now let’s continue and look in more detail at the physical cables themselves.

The copper cables used in Ethernet standards are UTP cables.

UTP stands for Unshielded Twisted Pair.

Unshielded means that the wires have no metallic shield, which can make them vulnerable to

eletrical interference.

The Twisted pair part is easy to understand from this photo, as you can see there are

four pairs of cables twisted together.

The twist actually helps protect against eletromagnetic interference, or EMI.

So, there are four pairs of wires twisted together, that makes eight wires in total.

Let’s take a look at one of those RJ-45 connectors we saw earlier

If you count the number of pins here, you’ll find that there are 8 pins, perfect for the

number of wires we saw in the last photo.

However, not all of the Ethernet standards we saw before actually use all 8 wires.

10BASE-T and 100BASE-T, also known as Ethernet and Fast-Ethernet cables, use 2 pairs, or

4 wires.

1000BASE-T and 10GBASE-T, however, use all 4 fours, or 8 wires.

Let’s focus on the first two for now, 10BASE-T and 100BASE-T.

So, let’s say we’re connecting a PC to a switch with a FastEthernet connection.

These numbers represent the pins on the RJ-45 on the PCs network interface card and the

switch’s interface.

There are 8, but we will only use 4, or 2 pairs, since this is a fastethernet, or 100base-t,

connection.

The first pair is at pin positions 1 and 2,

and will connect to pins at positions 1 and 2 on the switch’s network interface.

Although in this diagram the wires look straight, remember that in a UTP cable the pairs are

twisted together, so in a real cable these two wires would actually be twisted together

like in the photo we saw.

The PC will use pins 1 and 2 to transmit data to the switch,

which we can write as Tx.

Because the PC is transmitting data on pins 1 and 2, the switch cannot transmit on those

pins, it has to receive data

which we can write as Rx, on pins 1 and 2.

There’s an important point to remember here.

The network interface card on a PC or server transmits data on pins 1 and 2, and the interfaces

on a switch receive data on pins 1 and 2.

Now, the next pair that is used in a 10BASE-T or 100-BASE-T cable is not 3 and 4.

It’s 3 and 6.

And, of course, the function of each pin is opposite of the pair on pins 1 and 2.

On the switch,

Pins 3 and 6 are used to transmit Data, and on the PC

Pins 3 and 6 and used to receive data.

This allows what’s called Full-Duplex transmission.

Full-Duplex transmission means that both devices and send data at the same time, and no problems

like collisions will occur because they use separate wires to transmit and receive data.

Just like that, both devices send data at the same time and there are no problems.

Let’s change the device on the left from a PC to a router.

Just as a PC usually connects to a switch, a switch usually connects to a router.

Once again, it’s a fastethernet, or 100BASE-T connection, so two pairs are used, 1 and 2, and

3 and 6.

Now, which pairs on which side are used to transmit, and which are used to receive?

Well, we know how a switch functions from the last slide.

Pins 1 and 2 receive data,

and pins 3 and 6 transmit data.

How about a router?

Well, the network interfaces on a router transmit and receive data on the same pairs that a

PC’s network interface card does.

A router transmits data on pins 1 and 2

And receives data on Pins 3 and 6.

Again, Ethernet uses full-duplex transmission

So the two devices can send data at the same time with no issues.

So remember this, Routers transmit data on pins 1 and 2, and receive data on pins 3 and

6.

This is the same as a PC.

Once again, switches are the opposite, they receive data on pins 1 and 2 and transmit

data on pins 3 and 6.

When connecting a PC to a switch, or a Router to a switch, this works fine.

Because they transmit and receive on opposite pin pairs, a regular cable like this works

well.

This kind of cable, by the way, is called a straight-through cable.

Remember, a copper Ethernet cable has two RJ-45 connectors, one on each end.

This kind of a cable is called a ‘straight through’ cable because pin 1 on one end

connects straight through to pin 1 on the other end.

Pin 2 connects to Pin 2, Pin 3 connects to Pin 3, etc.

Now, in networks we don’t always connect PC to switch, switch to router.

What if we want to connect a router to another router?

Or maybe a switch to another switch?

Or maybe connect two PCs together?

Now I’ve replaced the switch on the right with another router.

What will happen if the router on the left sends data to the router on the right?

Well, it’s simply not going to work.

The right router isn’t prepared to receive data on pins 1 and 2 of its interface,

so communication between the two routers just doesn’t happen.

So, how can we successfully connect two routers together?

Or perhaps two switches, or two PCs.

The same thing applies to connecting a PC directly to a router, also, because they both

transmit data on pins 1 and 2, and receive data on pins 3 and 6.

Let’s take a look.

I’ve replaced the two routers with two switches, just to demonstrate that the same thing applies.

If the switch on the left tries to transmit some data to the switch on the right it doesn’t

work.

The answer to this problem is a different type of cable.

A straight-through cable connects pin 1 to pin 1, pin 2 to pin 2, pin 3, to pin 3, etc.

But there’s another type of cable, called a crossover cable.

In a crossover cable, a pin on one end of the cable doesn’t connect straight to the

same pin on the other end.

Essentially, the pairs are reversed on each end.

So, pin 1 on one side connects to

Pin 3 on the other side.

And pin 2 on one side connects to

Pin 6 on the other side.

As you can see, the two pairs, 1 and 2, and 3 and 6, are reversed.

Then, pair 3 on the left side will connect to Pin 1 on the right side.

And pin 6 on the left side will connect to pin 2 on the right side.

The wires are ‘crossed over’ each other, hence the name ‘crossover cable’.

The transmit pins on one side are connected to the receive pins on the other side, so

now the two devices can send data to each other with no problems.

Here’s another example.

Again, the network interface card on a PC and the network interfaces on a router both

transmit data on pins 1 and 2 and receive data on pins 3 and 6, however if you connect

them together with a crossover cable, they will be able to exchange data with no issues.

Here’s a chart reviewing different device types and the pins they use to transmit and

receive data

Routers transmit data on Pins 1 and 2, and receive data on pins 3 and 6.

Firewalls are the same as routers, they transmit data on Pins 1 and 2 and receive data on pins

3 and 6.

PCs also transmit data on Pins 1 and 2, and receive data on pins 3 and 6.

Switches are the only different one of the group.

Switches transmit data on pins 3 and 6, and receive data on pins 1 and 2.

Try to remember these.

The flashcards included in the description will help with this, so I recommend that you

use them!

While all of that is important information to know, and can cause issues in networks

even in the modern day, the truth is that most modern networking devices have evolved

beyond having to worry about straight-through or crossover cables.

That’s because newer networking devices include a feature called Auto MDI-X.

Previously, if two switches were connected with a straight-through cable like this, they

would be unable to communicate.

However, Auto MDI-X allows devices to automatically detect which pins their neighbor is transmitting

data on, and then adjust which pins they use to transmit and receive data.

They can then exchange data normally.

So, unless you’re working with network equipment that is quite old, you don’t really have

to worry about straight-through and crossover cables.

But this is good information to be aware of, and it’s also good to learn about the concept

of auto MDI-X, both for the exam and for real world networking.

So, we’ve talked a lot about 10BASE-T and 100BASE-T, but what about the higher speed

copper ethernet cables?

Remember, I said before that for gigabit ethernet and 10 gigabit ethernet, all 8 wires are used.

The last two pairs are 4 and 5, and 7 and 8.

Again, there will be flashcards to help you remember these details.

It may seem like a lot to memorize, but if you use the flashcards properly its amazing

how easy it is to remember all of these things.

Now, here’s another big difference between 1000baseT and 10GBASE-T, and 10base-t and

100-base-t.

In addition to using all four pairs of wires, in 1000base-T and 10Gbase-T, each pair is

bidirectional, meaning each pair isn’t dedicated specifically to transmitting data or receiving

data.

This is part of the reason that they can operate at much faster speeds.

Okay, we’ve covered a lot about connections using copper UTP cables.

But there is a newer technology that is superior in many ways.

For example, copper UTP wiring can be used for up to 100 meters.

that’s usually plenty within a LAN, but how about for larger networks?

Look at this Cisco switch here.

Here it has 24 ports for RJ45 connectors.

These are the ports you would connect a copper UTP cable to.

But what about these four interfaces?

Take a look at this Cisco router also.

It only has four RJ45 ports.

The rest of them look like those other four ports on the switch.

In these interface you insert one of these

It’s called an SFP transceiver.

SFP means small form-factor pluggable.

So you insert one of these into the device, but still things aren’t complete.

What kind of cable connects to one of these?

You connect one of these cables.

This is a fiber optic cable.

Rather than an electrical signal over copper wiring, these cables send light over glass

fibers.

Notice that there are two connectors on each end.

That’s because you need one connector to transmit data, and one to receive data, on

each end.

The copper UTP cables used separate wire pairs within the cable to transmit and receive data.

The fiber-optic cables instead use separate cables to transmit and receive, like this.

Of course, ‘transmit’ on the left connects to ‘receive’ on the right, and ‘transmit’

on the right connects to ‘receive’ on the left.

Now let’s examine the structure of the cable itself.

There are four numbered parts in this diagram, from the center to the outer layer.

Number 1 is the fiberglass core itself.

Light is transmitted down this core to transmit data from one device to another.

Number 2 is cladding that reflects light,

Number 3 is a protective buffer, which protects the fiberglass from breaking

and number 4 is the outer jacket of the cable.

Now there are a couple main types of fiber-optic cables.

single-mode fiber, and

multimode fiber.

Let’s check out their characteristics and differences.

These are two examples of multimode fiber cables.

The center represents the fiberglass core, and the blue represents the reflective cladding

that reflects light down the cable.

In multimode fiber cable, the core, the actual glass fiber, is wider than single mode fiber.

This wider core allows multiple angles, known as modes, of lightwaves to enter the fiber

glass core, as you can see in these two diagrams.

Notice the red and black lines representing light waves travelling down the fiberglass

core, reflecting off the cladding at different angles.

Multimode fiber allows longer cables than UTP, which are limited to 100 meters, but

still shorter than single-mode fiber, which we will look at next.

Multimode fiber cables are cheaper than single-mode fiber, and this is because they use cheaper

transmitters, which are often LED-based.

This is an example of a single-mode fiber cable.

Again, the center represents the fiberglass core, and the blue represents the reflective

cadding.

The core diameter of a single-mode fiber cable is narrower than a multimode fiber, meaning

the glass fiber is thinner.

You can notice this in the diagram here, compared to the multimode fiber diagrams.

Light enters at a single angle, known as a mode, from a laser-based transmitter.

Notice in the diagram that the light wave travels straight down the core of the cable.

Single-mode fiber allows longer cable lengths than both UTP and multimode fiber cables.

And single-mode fiber cables are more expensive than multimode fiber cables due to the more

expensive laser-based transmitters used.

Okay, now let’s look at some standards for fiber-optic cables like we did with UTP cables.

Here’s another chart like the one we looked at for copper UTP cable standards, this time

for fiber-optic cables.

First up is a standard for 1 gigabit ethernet over fiber, known as 1000BASE-LX.

It is defined in the IEEE 802.3zed, or zee, standard.

This standard can be used over single-mode or multimode fiber cables, and you can see

the difference in the maximum cable lengths, 550 meters for multimode fiber, and 5 kilometers,

or 5000 meters, for single mode fiber.

Next up is 10GBASE-SR, defined in the 802.3ae standard, which operates at 10 gigabits per

second.

It uses multimode fiber and can support cable lengths up to 400 meters.

Next is 10GBASE-LR, also defined in the 802.3ae standard, again operating at 10 gigabits per

second.

10GBASE-LR, however, uses single-mode fiber, and cables lengths can be up to 10 kilometers.

Finally 10GBASE-ER, also part of the 802.3ae standard, and operating at 10 gigabits per

second.

It supports cable lengths even longer than 10GBASE-LR, with distances up to 30 kilometers

possible over a standard connection.

This is just a sample of fiber-optic standards, there are plenty more.

I will include flashcards to help you remember these standards, but to be honest I doubt

you’ll be asked questions about specific details about the standards on the exam, but I don’t know

for sure.

However, with the flashcards it’s quite easy to remember little facts like these,

so I recommend not deleting those flashcards, but that’s your choice of course.

Finally, let’s review by comparing UTP cabling and Fiber-optic cabling, starting with UTP.

Copper UTP cables are cheaper than fiber-optic cables.

Maximum cables distances for UTP cables are shorter, about 100 meters maximum.

UTP cables can be vulnerable to electromagnetic interface, or EMI, although the twist in the

cable pairs helps to protect against this.

The RJ45 ports to which UTP cables connect are cheaper than the SFPs used for Fiber-optic

connections

Also, UTP cables emit, or leak, a faint signal outside of the cable, which could possibly

be detected and used to copy data, posing a possible security risk.

Now let’s look at fiber-optic cables.

Fiber-optic cables are more expensive than UTP cables

They support longer distances than UTP cables.

Their SFP ports are more expensive than RJ45 ports, and single-mode fiber ports are more

expensive than multimode.

They do not emit any signal outisde of the cable, so there is no security risk there.

Okay, so we covered a lot of information, but I want to remind you of the supplementary

materials for the video that will help you remember what you learned.

Like in the last video, there will be an end-of-video quiz starting from the next slide.

Also, I have made a deck of flashcards to help you review the information covered in this video,

check the link in the description to download them.

And there will also be a practice lab using Packet Tracer, which will be released as a

separate video.

Okay, let’s get started with the quiz.

Quiz question 1.

You connect two old routers together with a UTP cable, however data is not successfully

sent and received between them.

What could be the problem?

A, they are connected with a straight-through cable.

B, they are connected with a crossover cable.

or C, they are operating in auto MDI-x mode.

Pause the video to think about your answer.

The answer is A, they are connected with a straight-through cable.

let’s check each of the possible answers.

A crossover cable is not the issue.

In fact, a crossover cable would likely fix the issue.

Because both routers transmit data on pins 1 and 2, a crossover cable is necessary to

properly connect the transmit pins on one side to the receive pins

(3 and 6) on the other side.

Modern devices with Auto MDI-X enabled don’t have this issue, but it is possible that the

old routers do not have Auto MDI-X.

So, b, they are connected with a crossover cable, is incorrect.

Auto MDI-X allows devices to detect which pins and wires their neighbors are using to

transmit and receive data, and adjust their own operations to match.

Actually, Auto MDI-X would likely fix this issue, but since the routers are old they

might not have the Auto MDI-X function.

So, c, They are operating in Auto MDI-X mode, is incorrect.

On old devices without Auto MDI-X, a straight-through cable cannot be used to connect devices of

the same type.

A crossover cable is necessary.

So a, they are connected with a straight-through cable, is the best answer. Quiz question 2.

Your company wants to connect switches in two separate buildings that are about 150

meters apart.

They want to keep costs down, if possible.

What kind of cable should they use?

A, UTP.

B, Single-mode fiber, or C, multimode fiber.

Pause the video to think about your answer.

The answer is C, multimode fiber.

Let’s check.

Although UTP would keep the costs down, it does not support distances over 100 meters.

So A, UTP, is incorrect.

Although single-mode fiber supports distances much longer than 150 meters, it is more expensive

than multimode fiber.

So b, single-mode fiber, is not the best answer.

Multimode fiber supports distances over 150 meters and is less expensive than single-mode

fiber.

So C, multimode fiber, is the best answer.

Let’s go on to question 3.

Your company wants to connect two offices that are about 3 kilometers apart.

They want to keep costs down if possible.

Which kind of cable should they use?

A, UTP, B, single-mode fiber, or C, multimode fiber.

Pause the video to think about your answer.

The answer is b, single-mode fiber.

Let’s check the answers.

Although UTP keeps costs down, it does not support distances of 3 kilometers.

So A, UTP, is incorrect.

Although multimode fiber is cheaper than single-mode fiber, it also does not support distances of 3

kilometers.

So c, multimode fiber, is incorrect.

Many single-mode fiber standards support cable lengths much longer than 3 kilometers.

Although single-mode fiber is more expensive than the other options, it is necessary in

this case.

So B, multi-mode fiber, is the best answer.

A switch has the following indication over its network interfaces: What would happen

if you connect it to an identical switch with a straight-through cable?

A, they would operate normally.

B, they would operate at a reduced speed.

or C, they would be unable to communicate.

Pause the video to think about your answer.

The answer is a, they would operate normally.

Let’s check.

They would not operate at a reduced speed.

The ports are Auto MDI-X enabled.

However, even if they didn’t have Auto MDI-X, they wouldn’t operate at a reduced speed.

They simply wouldn’t operate.

So b, they would operate at a reduced speed, is incorrect.

Because the ports are Auto MDI-X enabled, they would be able to communicate, even though

they are connected with a straight-through cable.

So c, they would be unable to communicate, is incorrect.

Because the ports are Auto MDI-X enabled, they would operate normally, regardless of

whether they are connected with a straight-through or a crossover cable.

So a, they would operate normally, is the correct answer.

Let’s go to the final quiz question for this video.

Your company needs to connect many end hosts to a switch which is in a wiring cabinet on

the same office floor as the hosts.

What kind of cable should they use? a, UTP.

b, single-mode fiber, or C, multimode fiber.

Pause the video to think about your answer.

The answer is a, UTP.

Let’s check the answers.

Most hosts do not have the capability to connect to a switch via fiber cabling, and most switches

do not have enough SFP interfaces to support many hosts.

So b, single-mode fiber, and c, multimode fiber, are inorrect.

UTP cables are the standard for wired connections to switches.

Switches typically have many RJ45 ports for end hosts to connect to, and end hosts will

have an RJ45 port on their network interface card to connect a UTP cable to.

So a, UTP, is the correct answer.

Thank you for watching.

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