MÓDULO 1 - Video 1: Topologías y medios de transmisión

I warmly welcome you to this

video in which we will explain [music]

the main network topologies, their

main characteristics, and the

most important transmission media

used in the world today. Remember to

take notes and pause the video when you

need to.

Every morning, before starting his

workday, a worker turns on his

computer and within seconds has

access to [music], the internet, and his

information. No one has explained to him

why the network goes down completely when

someone unplugs a cable, or why in

other offices only

one computer stops working while the others

continue to work without a problem. That

difference is not a coincidence. [music]

It depends on how

the devices are physically connected to each other.

By the end of this video, [music]

you will have enough information to

explain to the worker what is

happening. Let's begin.

Computer networks are

the foundation of all

digital communications we use today. Each time

one device sends information to another,

that communication follows an

organized structure that defines how

the devices are connected, what paths

the data travels through, and how

access to the network is controlled. That structure is called

network topology.

Choosing a topology is not a

random decision; it depends on

very specific factors. The distance between

devices, how much [music] traffic is

expected on the network, how often it

needs to be available, how much

money is available to invest in

infrastructure, and the [music]

conditions of the location where it will

operate.

Throughout the history of networks,

different topologies have appeared,

[music] improved and in some cases

fallen out of use. Each one left her

mark on the communication systems

that are now part of our

daily lives. Identifying its characteristics

[music] allows us to understand how

the digital world around us works.

Some of the main ones are explained below

. Pay close attention.

Bus topology is one of the

oldest ways [music] of

networking computers. In this

configuration, all devices are

connected [music] to a single

main cable that runs throughout the

installation and through which all

information travels.

When a computer needs to send

data, it sends out a signal [music] that

travels through the cable in both directions.

All connected devices receive that

signal, but only the one with the

correct address [music] processes it.

The others simply ignore her.

The problem arises when two devices

try to send information at the same

time. This creates what is known as

a collision. The two signals get mixed up

and the data is lost, forcing the

teams to [music] wait and

try again. In networks with many

devices, this slowed down all

communication. Physically, the signal

also weakened with distance,

[music] a phenomenon called attenuation.

In addition, environmental interference and

ambient electrical noise

could distort the data. To

prevent the signal from bouncing back when it reached

the end of the cable,

small components

called terminators were placed at each end.

In [music] this table shows

some of the main advantages and

disadvantages of this topology. [music] I

invite you to pause the video for a moment

so you can consult them in

detail.

This topology was installed primarily

with coaxial cable connected using

small pieces called BNC connectors.

Its speed [music] was 10 MB per

second, sufficient for the time, but

over time its limitations

displaced it [music]. Today it is considered

a historical technology, although its

basic principles are still alive in

industrial systems and in the

electronics of modern automobiles.

The Token Ring topology [music] connects

devices forming a

closed ring. Each device is connected to the

next via its own

cable segment and data always flows in the

same direction, passing through

each node until the circle is complete. The

most interesting thing [music] about this

architecture is how it controls

network access. There is a special little signal

[music] called a token or

witness that circulates constantly around

the ring. When a

device needs to send data,

it waits for the token to reach it,

takes it, marks it as busy, and

transmits its information. The other

teams see that the [music] channel is

in use and wait their turn. Once

the transmission is finished, the token is

released [music] and continues its journey.

This system completely eliminates

collisions.

Token Ring operated at speeds of 4 and

16 MB per second and was widely used in

banks and businesses during the 1990s.

Its decline came when Ethernet

proved to be cheaper and more flexible.

However, the token concept remains

alive in industrial protocols such as

Profibus, used today in factories and

automation systems. [music]

Star topology is the most used in

current networks. In this

configuration, each device

has its own cable that connects it

directly to a central piece of equipment

called a Switch. There is no

shared cable. Each computer has its

own exclusive communication channel.

When using a switch, this equipment is

smart enough to

send data only to the

intended device without

disturbing others. This eliminates

collisions and makes the network much

more efficient. If a hub is used,

the signal reaches all devices

at the same time, which can cause

conflicts.

The most common cable in this topology is

UTP. That gray or blue cable with

plastic [music] terminals that you see

in any office. Its maximum length

is 100 m. Music speeds

range from 100 MB per second in

basic installations to 10

GB per second in

high-performance enterprise networks. Its

main advantage is that if

a computer cable breaks, only

that computer loses its connection. The

others are still working. Its only

real disadvantage is that if the

central switch fails, the entire network stops.

Even so,

its ease of installation and

maintenance makes it the

favorite choice in homes, schools,

offices and hospitals around the world.

Tree topology, also called

hierarchical, organizes teams into

levels [music] like a pyramid. At

the top is the

main equipment that manages traffic across

the entire network, followed by

intermediate switches that handle

different areas or floors, and at

the bottom are the

users' computers and devices. This

tiered organization makes it

very easy to grow [in music]. If

more equipment needs to be connected,

simply add another switch at the

appropriate level without

affecting the rest. Furthermore, it allows for the

logical separation of different areas

within a company, which improves

security and traffic control.

In large buildings, fiber

optic cable connects the switches

between floors, while UTP cable

reaches every desk. It is the

standard model in universities,

hospitals, and multi-story companies.

The main disadvantage [of music] is that

if the main switch fails, all

lower levels are left without

communication.

Mayan topology takes redundancy

to the extreme. In this configuration, each

device is directly connected

to several others, creating multiple

possible routes for the [music]

data to reach its destination. If any

route fails, the data simply takes

another path without the user noticing

any interruption. In its

complete form, all devices are

interconnected, offering the

highest possible fault tolerance, but it is

very expensive. Therefore, in

practice [music] a partial mesh is used

, where each piece of equipment connects

only to some of the others, achieving

a balance between redundancy and cost.

The Internet as a whole operates under

this principle. Major

internet providers [for music] connect their nodes

in different cities using

fiber optic cables at speeds of 100 GB per

second or more. ARPANET, the

predecessor network to the internet, was the first

implementation of this concept in 1969.

Today it is the standard for any

infrastructure where

continuous availability is essential.

Hybrid topology combines two or more

types of topology within the same

network. Their goal [in music] is to take the

advantages of each and apply them where they are

most appropriate. In practice, [music]

almost all real networks are

hybrid. For example, a

university campus might use

star topology within each

building to connect computers

to the switch on each floor, tree topology

to organize switches

between different floors, and

mesh topology to connect different

buildings to each other using

redundant fiber optics. This allows

that if one building loses its connection,

the others continue to function, and if a

cable inside a building is damaged,

only that computer is affected.

The flexibility of hybrid topology

is its greatest advantage. The biggest challenge is the

complexity of management, as it requires

specialized technical personnel to

keep it functioning properly.

Now that you've identified the

network topologies, you can answer the worker's question, which

at first seemed like a mystery. If

the entire network went down because of a single

disconnected cable, the office had a

bus topology. If only one computer was affected

, [music] the network was

organized in a star topology. The way

devices are connected determines

the resilience, [music] performance,

and cost of the entire infrastructure.

That decision, [music] that seems

technical and distant is behind every

screen that lights up every morning.

With this in mind, I now invite you to

think about the following situation. A

student arrives home after

class and notices that his

internet connection is slow when using Wi-Fi

from his room, but smooth when

he connects the cable directly to his

computer. At school, on the other hand,

the network never fails, even though there are

dozens of computers connected at the same

time. He wonders why there is that

difference [in music] and what makes

some means of connection work

better than others depending on the place and

situation.

Every time [music] a device

sends information to another, it needs a

path for that information to reach

its destination. This is called the

transmission medium. It is a channel through which

data travels in the form of

electrical signals [music], light pulses, or

radio waves. There are guided media

such as copper cable and [music]

fiber optics and unguided media such as

Wi-Fi and cellular networks. The choice

of medium determines the speed,

[music] distance and resistance to

interference of the entire network.

Some of them are explained below

. The UTP [music] cable has

four pairs of twisted copper wires

. It is the most widely used medium in

current local networks. Their pairs are

intentionally intertwined

[music]

to reduce interference

between them. It is classified by

categories that define its speed and

bandwidth. Category 5, now

obsolete, supported up to 100 MB per

second. Category 6 includes an

internal separator that further reduces

interference [music] and can reach

10 GB per second, although at that

maximum speed its range is limited

[music] to 55 m. Category 7 adds

metallic shielding around each

pair of wires and an additional shield around

the entire assembly, making it

ideal for environments with a lot of

electrical interference. like

[music] factories or data centers. They all

end in RJ45 connectors,

those small transparent plastic [music] ones

that plug into the

computer or switch.

Another medium is fiber optics. It works

on a completely different principle

than copper. Instead of electricity,

it transmits pulses of light through a

strand of ultrapure glass. Light bounces

inside the thread through a phenomenon

called total internal reflection. which

allows it to travel great distances

with very little signal loss.

There are two main types.

Single-mode fiber has a very

thin core of only 8 to 10 thousandths of a

millimeter, allowing only a single

beam of light to travel through it

. This makes it capable of covering

distances [music] of up to 80 km at

speeds exceeding 100 GB per

second. Music is used in

long-distance connections, such as

submarine cables that link continents.

Multimode fiber has a wider core

that allows multiple

simultaneous beams of light.

It is more economical and is used inside

buildings and data centers with

ranges of up to 300 m. The

most modern versions classified as OM3, OM4

and OM5 support speeds of 10 to 100

GB per second.

On the other hand, Wi-Fi networks allow you

to connect wirelessly using

radio waves. That's why they are wireless media.

They are defined by standards

developed by an organization

called

IEEE under the name 802.11.

[music]

Each version of this standard has brought

improvements in speed and efficiency.

The first two standards appeared in 1999

. 802.11

operated in the 5 GHz band and reached

[music] 54 MB per second, but had

little range. The 802.11 [music]

11B. It operated at 2.4 GHz with only 11 MB

per second, but had better coverage

and was the first to be

massively adopted in laptops and

homes. In 2003, [music]

802.11G

combined the best of both. It operated at 2.4

GHz, but with speeds of up to 54 MB

per second, being compatible with

previous devices. It was the

dominant standard for several years. In 2009,

802.11N,

also called WiFi 4, arrived.

It introduced two major advances: the

ability to choose between 2.4 and 5 GHz

depending on environmental conditions, and the

use of multiple antennas to transmit

several data streams at the same time.

Technology known as MIMO reached

up to 600 MB per [music] second.

In 2014 came 802.11 11 AC or WiFi 5,

which operated exclusively on 5 GHz with

speeds of up to 3.5 GB per second.

It incorporated wider channels and the

ability to serve multiple

devices simultaneously,

making it the standard for

online video streaming and gaming.

Wi-Fi 6, [music] released between 2019 and

2021 changed the approach. In addition to seeking

[music] more speed, it was designed to

work well in spaces with many

devices connected simultaneously,

[music]

such as stadiums or airports. It incorporated

techniques that distribute the channel among

several devices at once, reducing

[music] waiting times. Its

theoretical speed reaches 9.6 GB per

second.

Interesting, isn't it? How are you doing so far?

All good? Remember, if you have any

questions, take note and discuss them with your

facilitator. Okay, now let's talk about

Bluetooth. Its development began in 1994

in

Ericsson's laboratories and its name refers

to the Viking king Harold Blattand,

translated into English as Harold

Bluetooth, who in the 10th century unified

disputing Danish tribes, just as the

technology seeks to unify

communication protocols between

different manufacturers. However, Bluetooth

is also a

short-range wireless communication technology

designed for the interconnection

of electronic devices within

a personal space or personal area.

PAN Personal Area Network, without the need

for cables. For their part,

cellular networks allow you to communicate [music]

on the move from anywhere with

coverage. The territory is divided into

zones called [music] cells, each

served by an antenna. When the

user moves from one

cell to another, the network automatically transfers the

connection without

interruption.

The third generation or 3G launched in

2001 was the first designed to

transmit digital data. It allowed users to

browse the internet from their phone,

check their email, and make basic video calls

. Their speeds ranged from 384 KB

to 2 MB per second. The fourth

generation or 4G LTE arrived in 2009 with

a completely

internet-based architecture. It reached speeds

of up to 100 MB per second, making it

possible to watch high-

definition videos from your cell phone, use

real-time map applications, and

make high-quality voice calls

. The 4.5G version

improved that standard without requiring

major infrastructure changes,

reaching up to 3 GB per second

[music] under optimal conditions. It paved

the way for the Internet of

Things, connecting sensors, cameras, and

industrial equipment [music] to the

mobile network. The fifth generation or 5G arrived

in 2019 with [music] three great

capabilities. First,

extreme speeds of up to 20 GB per second

[music] for individual users.

Second, the ability to connect

up to 1 million devices per

square kilometer, ideal for

smart cities and industrial sensors.

Third, a latency [music] of just

1 millisecond, which allows for

real-time remote machine control,

enabling remote surgeries and managing

autonomous vehicles. The latest version

, 5.5G,

began deployment in 2024. It adds the

ability for antennas to

detect objects in their environment while

transmitting data. It improves coverage

for drones and aerial devices and

serves as a technological bridge to the

next generation of

mobile communications. [music]

Now you recognize that the difference between

a slow Wi-Fi connection and a stable

[music] wired connection is not accidental,

but the direct result of the

transmission medium used. Copper cable

offers a dedicated channel without

interference, while wireless [music]

signals share space

with other devices and weaken with

walls. The school's network

works stably because it

uses structured cabling designed

to support multiple

simultaneous connections. Each medium has its own

characteristics, and knowing them allows

for better decisions when

designing or using a network.

We've reached the end. Don't forget to practice

what you learned in this video. Could you

[music] identify which topology and

transmission medium is used in your

environment? Best of luck and see you soon.