Module 1: Introduction to Computer Networking

Welcome to Course 2, The Bits and Bytes of
Computer Networking. You might remember me from the lessons on the Internet
in the first course, but you also might
have jumped ahead, in which case we are
meeting for the first time. My name is Victor Escobedo and I’m a Corporate
Operations Engineer. My passion for IT began
way back when I was nine years old and my dad brought home our first computer. He was a mechanical
engineer and started using the computer to help
him with his Cadwork. This was the first time I
was exposed to computers, and later realize that you
can install new software on it, including computer games. As I tinkered with the computer, surely to my dad’s dismay, I became more and more
interested in how it worked and eventually started open up the case
and peek inside. I found pieces that could be removed and even
some that shouldn’t. Learning through trial
and error along the way. I couldn’t really
explain what it was, but I just found the
mechanics of how it all worked together
so fascinating. Looking back, these were the seeds that
inspired my career. But you see where I grew up
going to college and pursuing a career wasn’t exactly talked about or
heavily encouraged. I’m a first-generation
Mexican American and there weren’t a lot of people I knew
pursuing a career in tech. My friends and family were
mostly worrying about graduating high school and
making sure they had jobs. Not really thinking about
longer-term careers. My school didn’t
have the resources to offer many technical classes. Even though my father was working in mechanical
engineering, computers were a tool to him, like a mill, ruler, or hammer. My parents encouraged me to work hard and pursue computers, but they couldn’t really give me advice about college
or a career in tech. It’s not real a
fault of their own, they just didn’t have the
experience necessary. When I decided to go to college, I decided to try my hand at computer science
since it could feed my curiosity for how computers worked at a more
fundamental level. I realized that having this foundational knowledge
really allowed me to understand some of the
higher-level concepts that were important
in a career in IT. While in school, I
took my first job in IT for a small local company. I’ve been working in
IT for 12 years now, with the last seven years
being here at Google. I now work on managing
deployments of large internal IT
projects for the company. Applying the knowledge
I’ve picked up over the years in my initial
helpdesk role to make sure that I
understand how I’m impacting our users and
various support teams. In my role as a corporate
operations engineer, I’m responsible
for understanding the impact of changes on our
corporate infrastructure. Because of this, networking
skills are critical. I need to understand
not just how applications work
on a single system, but how they interact with all other systems in the
company and even externally. Now that you know
a bit about me, let’s dig into the bits
and bytes of networking. Computers communicate with each other a lot like how humans do. Take verbal communication
as an example, two people need to
speak the same language and be able to hear each other to communicate
effectively. If there are loud noises, one person might have to ask the other person to
repeat themselves. If one person only somewhat understands an idea
being explained to them, that person might ask
for clarification. One person might address
only one other person, or they may be
speaking to a group. There’s usually a greeting and a way to close the conversation. The point is that humans
follow a series of rules when they communicate and computers
have to do the same. This defined set of standards
that computers must follow in order to communicate properly is called the protocol. Computer networking is
the name we’ve given to the full scope of how computers communicate
with each other. Networking involves
ensuring that computers can hear each other, that they speak protocols other
computers can understand, and that they repeat messages
not fully delivered. Just like how
humans communicate. There are lots of
models used to describe the different layers at play
with computer networking. But for this course, we’ve selected the
TCP/IP five-layer model. We’ll also be touching on the other primary network model, the OSI model, which
has seven layers. If you don’t know
what these models are or how they
work, don’t worry. We’ll be deep diving into these topics throughout
this course. It’s super important to know these types of layered models to learn about computer networking because it’s a really
layered affair. The protocols at each
layer carry the ones above them in order to get data from one place to the next. Think of the protocol
used to get data from one end of a networking
cable to the other. It’s totally different from
the protocol used to get data from one side of
the planet to the other. But both of these protocols
are required to work at the same time in
order for things like the Internet and
business networks to work the way they do. Sometimes there are
problems when computers on the internet or on
these business networks try to communicate
with each other. Often it’s up to an IT support specialist
to fix these problems. This is why understanding computer networking
is so important. By the end of this course, you’ll be able to explain all
five layers of our model. Not only that, you’ll be able to describe how computers
determine where to send their messages and how network services
like DNS and DHCP work. You’ll also be able to use powerful tools to help you
troubleshoot network issues. Are you ready? Let’s dive in.

Here’s a tutorial on the TCP/IP Five-Layer Network Model, incorporating images for clarity:

Understanding Network Communication with Layers

Imagine how complex it would be to send a message if you had to manage every aspect of the process, from electrical signals to routing to application-specific tasks. The TCP/IP model simplifies this by breaking down network communication into five distinct layers, each with its own responsibilities.

1. Physical Layer: The Hardware Foundation

• Physical components: Cables, connectors, network interfaces, wireless devices.
• Function: Transmits raw bits of data over a physical medium.
• Analogy: The roads and vehicles that carry packages.

2. Data Link Layer: Local Delivery and Organization

• Key protocol: Ethernet (others include Wi-Fi, Bluetooth).
• Functions:
  • Organizes bits into frames for efficient transmission.
  • Detects and corrects errors within a local network.
• Analogy: Traffic lights and rules for moving between intersections.

3. Network Layer: Routing Across the Internet

• Key protocol: IP (Internet Protocol).
• Functions:
  • Assigns IP addresses to devices for identification.
  • Routes data packets across multiple networks to their destinations.
• Analogy: Maps and GPS for determining the best routes.

4. Transport Layer: Reliable Delivery and Connections

• Key protocols: TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).
• TCP:
  • Ensures reliable, ordered delivery of data.
  • Establishes connections, handles retransmission of lost packets.
• UDP:
  • Faster, but less reliable, without guaranteed delivery.
  • Used for real-time applications like video streaming.
• Analogy: Delivery confirmation and tracking for packages.

5. Application Layer: User-Facing Applications and Services

• Protocols: HTTP (web browsing), FTP (file transfer), SMTP (email), DNS (domain name resolution), and many more.
• Function: Provides specific services to users and applications.
• Analogy: The actual content of the delivered packages.

Key Points to Remember:

• Data flows down through the layers for sending, and up through the layers for receiving.
• Each layer communicates with its corresponding layer on the receiving device.
• The TCP/IP model is a conceptual framework, not a strict implementation.
• Understanding the layers helps in troubleshooting network issues and designing efficient network architectures.

To really understand networking, we need to understand all
of the components involved. We’re talking about everything from the
cables that connect devices to each other to the protocols that these
devices use to communicate. There are a bunch of models that help
explain how network devices communicate but in this course we’ll
focus on a five layer model. By the end of this lesson, you’ll be able
to identify and describe each layer and what purpose it serves. Let’s start at the bottom of our
stack where we have what’s known as the physical layer. The physical layer is
a lot like what it sounds. It represents the physical devices
that interconnect computers. This includes the specifications for
the networking cables and the connectors that join
devices together along with specifications describing how signals
are sent over these connections. The second layer in our model
is known as the data link layer. Some sources will call this
layer the network interface or the network access layer. At this layer we introduce
our first protocols. While the physical layer is all about
cabling, connectors, and sending signals, the data link layer is responsible for
defining a common way of interpreting these signals so
network devices can communicate. Lots of protocols exist at
the data link layer but the most common is known as ethernet. Although wireless technologies
are becoming more and more popular. Beyond specifying physical layer
attributes, the ethernet standards also define a protocol responsible for getting
data to nodes on the same network or link. The third layer, the network layer, is
also sometimes called the internet layer. It’s this layer that allows different
networks to communicate with each other through devices known as routers. A collection of networks connected
together through routers is an inter network, the most famous of
these being the internet. Hopefully you’ve heard of it. While the data link layer is responsible
for getting data across a single link, the network layer is responsible for getting data delivered across
a collection of networks. Think of one of the device on your
home network connects with a server on the internet. It’s the network layer that helps get
the data between these two locations. The most common protocol used at this
layer is known as IP or internet protocol. IP is the heart of the internet and
most small networks around the world. Network software is usually
divided into client and server categories with the client
application initiating a request for data and the server software answering
the request across the network. A single node may be running multiple
client or server applications. So you might run an email program and
a web browser. Both client applications on
your PC at the same time and your email and web server might
both run on the same server. Even so, emails end up in
your email application and web pages end up in your web browser. That’s because our next layer,
the transport layer. While the network layer delivers
data between two individual nodes, the transport layer sorts
out which client and server programs are supposed
to get that data. When you heard about our
network layer protocol IP, you may have thought of TCPIP,
which is a pretty common phrase. That’s because the protocol most
commonly used in the fourth layer, the transport layer, is known as TCP or
transmission control protocol. While often said together as the phrase
TCPIP, to fully understand and troubleshoot networking issues, it’s
important to know that they’re entirely different protocols serving
different purposes. Other transport protocols also
use IP to get around including a protocol known as UDP or
user data gram protocol. The big difference between the two is
that TCP provides mechanisms to ensure that data is reliably
delivered while UDP does not. Spoiler alert will cover
differences between the TCP and UDP transport protocols
in more detail later. For now, it’s important to
know that the network layer, in our case IP is responsible for
getting data from one node to another. Also remember that the transport layer,
mostly TCP and UDP is responsible for ensuring that data gets to the right
applications running on those nodes. Last but not least, the fifth layer
is known as the application layer. There are lots of different
protocols at this layer and as you might have guessed from the name,
they’re application specific. Protocols used to allow you
to browse the web or send and receive email are some common ones. The protocols that play in the application
layer will be most familiar to you since there are ones you probably interacted
with directly before even if you didn’t realize it. You can think of layers like different
aspects of a package being delivered. The physical layer is
the delivery truck and the roads. The data link layer is how the delivery
trucks get from one intersection to the next over and over. The network layer identifies which
roads need to be taken to get from address A to address B. The transport layer ensures that delivery
driver knows how to knock on your door to tell you your package has arrived. And the application layer is
the contents of the package itself.

Every computing device
that we interact with on a daily basis is
a network device. Computers aren’t stand-alone
anymore in any way. From our phones, to a
tablets, to a laptops, to a desktops, they’re all
networked in some way. They’re all talking
to other computers. To a lot of people networking
is seen as some black magic and only certain people really understand
what’s going on. But in my experience, an IT support person who truly understands networking
at a fundamental level, is just able to perform every aspect of their job
so much more successfully. There are a lot of networking
courses available. This is actually something
that people have been teaching in this
manner since the 90s. But I think this course is
really different because it focuses on so many
practical cases, as well as really focusing
on the things that an IT support person
needs to know and not necessarily
a network engineer. We spend time on DNS. We spend a lot of time on different troubleshooting
techniques and tools. We spend a lot of
time just focusing on the things that on
a day-to-day basis, someone in IT actually
needs to know about.

Networking Cables and Devices Tutorial: Connecting Your Network

Welcome to the world of networking! This tutorial will guide you through the essential building blocks of a healthy network: cables and devices. By the end, you’ll be able to identify, describe, and understand how they work together to keep your computers talking.

Part 1: Cables – The Conduits of Communication

1. Copper vs. Fiber: The two main players in the cable game are copper and fiber.
   • Copper cables: The workhorses of networking, affordable and widely used. They transmit data using electrical pulses through twisted pairs of insulated wires. Common types include Cat5, Cat5e, and Cat6, each with different levels of data transfer rate and crosstalk resistance (unwanted signal interference). Cat6e and Cat7 offer even higher speeds but are less common.
   • Fiber optic cables: These high-speed champions use pulses of light through thin glass strands. They’re immune to electromagnetic interference, offer superior speed and distance, but come at a higher cost and require delicate handling.
2. Choosing the Right Cable: It depends on your needs! Copper is cheaper and simpler for short-distance home or office networks. Fiber shines in data centers and situations demanding high speed and long distances.

Part 2: Devices – The Network Orchestrators

1. Network Adapter: Every device that wants to join the network party needs a network adapter. This translates data into a language the network understands and vice versa. Think of it as a translator for the digital world.
2. Hubs and Switches: In the early days, hubs reigned supreme. They simply copied incoming data to all connected devices, creating a noisy echo chamber. Today, switches rule the roost. They intelligently direct data only to the intended recipient, making for a more efficient and streamlined network.
3. Routers: The traffic cops of the network! Routers manage data flow between different networks, directing packets to their correct destinations, even if they reside on different highways (subnets). Think of them as road signs and toll booths guiding data to its final address.
4. Wireless Access Points (WAPs): Ditch the cables and embrace the freedom of the airwaves! WAPs act as bridges between wired and wireless networks, translating signals and letting your devices connect without cords.
5. Modems: For connecting to the wider world of the internet, you’ll need a modem. It acts as a translator between your network and the internet service provider (ISP), converting information into signals compatible with their infrastructure.

Part 3: Putting it All Together:

Imagine your network as a highway system. Cables are the lanes, devices are the traffic controllers, and data packets are the cars zipping around. Choosing the right types and configurations ensures smooth communication and prevents traffic jams.

Bonus Tip: Remember, networking isn’t just about hardware! Software like firewalls and network management tools play crucial roles in security and performance.

Ready to Explore Further?

This is just the tip of the networking iceberg! Keep learning about protocols, network topologies, security best practices, and advanced devices like firewalls and load balancers. The deeper you go, the more control you’ll have over your own digital ecosystem.

I hope this tutorial has brought some clarity to the fascinating world of networking cables and devices. Feel free to ask any questions you have, and keep exploring!

Remember:

• Practice makes perfect! Experiment with different cables and devices to understand their strengths and weaknesses.
• Don’t be afraid to research and learn! The more you know, the more empowered you are to build and maintain efficient networks.
• Networking is a journey, not a destination. Enjoy the ride!

Lots of different cables and network
devices can be used to allow computers to properly communicate with each other. By the end of this lesson,
you’ll be able to identify and describe various networking cables and
networking devices. Computer networking is a huge part of the
day to day role of many IT specialists. And knowing how to differentiate different
network devices will be essential to your success. Let’s start with the most basic
component of a wired network, cables. Cables are what connect
different devices to each other, allowing data to be transmitted over them. Most network cables used today can be
split into two categories, copper and fiber. Copper cables are the most
common form of networking cable. They’re made up of multiple pairs of
copper wires inside plastic insulator. You may already know that
computers communicate in binary, which people represent with ones and
zeros. The sending device communicates binary
data across these copper wires by changing the voltage between two ranges. The system at the receiving end is able to
interpret these voltage changes as binary ones and zeros which can then be
translated into different forms of data. The most common forms of copper twisted
pair cables used in networking are Cat5, Cat5e and Cat6 cables. These are all shorthand ways of saying
category five or category six cables. These categories have different physical
characteristics like the number of twists in the pair of copper wires that
result in different usable lengths and transfer rates. Cat5 is older and has been mostly
replaced by Cat5e and Cat6 cables. From the outside,
they all look about the same and even internally they’re very
similar to the naked eye. The important thing to know is that, differences in how the twisted pairs
are arranged inside these cables can drastically alter how quickly
data can be sent across them. And how resistant these signals
are to outside interference. Cat5e cables have mostly replaced
those older Cat5 cables because their internals reduce Crosstalk. Crosstalk is when an electrical
pulse on one wire is accidentally detected on another wire,
so the receiving end isn’t able to understand
the data causing a network error. Higher level protocols have methods for
detecting missing data and asking for the data a second time. But, of course, this takes up more time. The higher quality specifications of
a Cat5e cable make it less likely that data needs to be re transmitted. That means on average you can
expect more data to be transferred in the same amount of time. Cat6 cables follow an even more
strict specification to avoid Crosstalk making those
cables more expensive. Cat6 cables can transfer data faster and more reliably than Cat5e cables can, but
because of their internal arrangement, they have a shorter maximum distance
when used at higher speeds. The second primary form of networking
cable is known as fiber, short for fiber optic cables. Fiber cables contain individual optical
fibers which are tiny tubes made out of glass about the width of a human hair. These tubes of glass can
transport beams of light. Unlike copper, which uses electrical
voltages, fiber cables use pulses of light to represent the ones and
zeros of the underlying data. Fiber is even sometimes used specifically
in environments where there’s a lot of electromagnetic interference
from outside sources. Because this can impact data
being sent across copper wires. Fiber cables can generally transport
data quicker than copper cables can, but they’re much more expensive and fragile. Fiber can also transport data over much
longer distances than copper can without suffering potential data loss. Now you know a lot more about the pros and
cons of fiber cables. But keep in mind, you’ll be way more
likely to run into fiber cables in computer data centers than you
would in an office or at home.

Hubs vs. Switches: A Networking Showdown

In the vast landscape of technology, networks play a crucial role in keeping everything connected. But have you ever wondered how multiple devices talk to each other? Enter the stage: hubs and switches, the unsung heroes of network communication!

Let’s Start with the Basics: Point-to-Point Connections

Imagine two kids with walkie-talkies whispering secrets. That’s a simple point-to-point connection – perfect for sharing a joke, but not ideal for a classroom full of chattering students. Similarly, point-to-point connections work for basic communication, but for a network with multiple devices, it’s chaotic!

Enter the Hub: The Noisy Gossip Mill

Think of a hub as a central bulletin board where everyone shouts their messages. Every connected device receives everything, just like in our classroom analogy. Imagine the confusion! This creates an environment called a “collision domain,” where devices fight for airtime, leading to delays and frustration (just like our noisy classroom).

The Switch Emerges: A Smart Traffic Cop

Enter the switch, the sophisticated cousin of the hub. It works more like a personal assistant, listening to each device’s message and then politely forwarding it only to the intended recipient. No more shouting across the room! This dramatically reduces collisions and keeps the network flowing smoothly.

Here’s a table to summarize the key differences:

So, who wins the battle?

In today’s world, the switch is the undisputed champion. Its ability to handle collisions and improve network performance makes it the go-to device for efficient communication.

Want to explore further?

This is just the tip of the iceberg! More advanced topics like packet switching, network topologies, and security protocols can take your networking knowledge to the next level. Remember, practice makes perfect! Experiment with different network configurations to see how hubs and switches impact performance.

By understanding the heroes and villains of network communication, you’ll be better equipped to build and maintain efficient networks that keep your devices talking (without the unnecessary noise!).

I hope this tutorial has clarified the differences between hubs and switches. Feel free to ask any questions you have, and keep exploring the fascinating world of networking!

We’re going to do a rundown of network
devices in this video and the next one. Almost every IT specialist will have
to interact with these sorts of devices on a regular basis. Cables allow you to form point
to point networking connections. These are networks where only a single
device at each end of the link exists. Not to knock point to point
networking connections but they’re not super useful in a world
with billions of computers. Luckily there are network
devices that allow for many computers to
communicate with each other. The most simple of these devices is a hub. A hub is a physical layer
device that allows for connections from many computers at once. All the devices connected to a hub will
end up talking to all other devices at the same time. It’s up to each system connected to
the hub to determine if the incoming data was meant for them or
to ignore it if it isn’t. This causes a lot of
noise on the network and creates what’s called a collision domain. A collision domain is a network
segment where only one device can communicate at a time. If multiple systems try
sending data at the same time, the electrical pulses sent across
the cable can interfere with each other. This causes these systems
to have to wait for a quiet period before they
try sending their data again. It really slows down
network communications and is the primary reason
hubs are fairly rare. They’re mostly a historical
artifact today. A much more common way of connecting many
computers is with a more sophisticated device known as a network switch,
originally known as a switching hub. A switch is very similar to a hub, since
you can connect many devices to it so they can communicate. The difference is that while
a hub is a layer one or physical layer device, a switch is
a layer two or data link device. This means that a switch can actually
inspect the contents of the ethernet protocol data being sent around
the network, determine which system the data is intended for and then only
send that data to that one system. This reduces or even completely eliminates the size
of collision domains on a network. If you guess that this will lead
to fewer retransmissions and a higher overall throughput, you’re right.

Routers: The Unsung Heroes of the Internet

Ever wondered how you can click on a website halfway across the globe and instantly see its content? You can thank the humble router, the unsung hero of the internet! In this tutorial, we’ll explore the role of routers in networks, diving into their functions, types, and importance.

Connecting the Dots:

Imagine a bustling city where information flows like traffic. Hubs and switches are like city blocks, connecting devices within their own neighborhoods. But to reach distant destinations, we need something like a highway network. That’s where routers come in.

The Wise Traffic Guides:

Unlike hubs and switches that operate within individual networks, routers work at the level of independent networks. Think of them as the traffic cops at intersections, reading directions (IP addresses) and directing data packets onto the optimal highways (network paths). They analyze these packets, identifying their destination networks and choosing the most efficient route to get them there.

Understanding the Layers:

Think of networking as a layered system. Hubs and switches operate at the lower layers, dealing with physical connections and data formats. Routers, however, belong to the network layer, where the focus is on addressing and routing information across independent networks.

Home vs. Global Heroes:

Just like cars and trucks, routers come in different sizes and capabilities. Your home router connects your devices to the internet, with a relatively simple routing table for directing traffic to your ISP. But in the heart of the internet, massive core routers form the backbone, handling global traffic with complex routing tables and sophisticated algorithms. These giants learn about optimal paths through a protocol called BGP (Border Gateway Protocol), constantly adapting to ensure smooth data flow across countless connections.

The Internet Symphony:

Picture the internet as a vast orchestra, where data packets are the notes and routers are the conductors. Each router plays a crucial role, reading the “sheet music” (IP addresses), coordinating data flow, and ensuring every packet reaches its destination in perfect harmony.

Exploring Further:

This is just the beginning of your router journey! You can delve deeper into topics like:

• Different routing protocols and algorithms
• Network topologies and routing paths
• Security considerations for routers
• Advanced configuration options for power users

Remember, practice makes perfect! Experiment with network simulators and routing software to gain hands-on experience with this fascinating world.

So, next time you browse the web, take a moment to appreciate the silent heroes – the routers – guiding your information journey across the globe.

I hope this tutorial has made routers less mysterious and more fascinating! Feel free to ask any questions you have, and keep exploring the exciting world of networking!

Hubs and switches are the primary devices used to connect computers on
a single network, usually referred to as a LAN
or a Local Area Network. But we often want
to send or receive data to computers
on other networks. This is where routers
come into play. A router, is a device that knows how to forward data between
independent networks. While a hub is a
layer one device and a switch is a layer two device. A router operates at layer
three, a network layer. Just like a switch can inspect Ethernet data to determine
where to send things, a router can inspect IP data to determine
where to send things. Routers store internal tables containing information about how to route traffic between lots of different networks
all over the world. The most common type of
router you’ll see is one for a home network
or a small office. These devices generally don’t have very detailed
routing tables. The purpose of these routers is mainly just to take
traffic originating from inside the home or
office land and to forward it along to the ISP
or Internet Service Provider. Once traffic is at the ISP a way more sophisticated
type of router takes over. These core routers form the backbone of the
internet and are directly responsible for how
we send and receive data all over the internet
every single day. Core ISP routers
don’t just handle a lot more traffic than a
home or small office router. They also have to deal with much more complexity in making decisions about where
to send traffic. A core router usually has many different connections
to many other routers. Routers share data with
each other via a protocol known as BGP or Border
Gateway Protocol. That lets them learn about the most optimal paths
to forward traffic. When you open a web browser
and load it web page, the traffic between computers
and the web servers could have traveled over
dozens of different routers. The Internet is incredibly
large and complicated, and routers are
global guides for getting traffic to
the right places.

Servers and Clients: The Yin and Yang of the Digital World

In the bustling metropolis of the internet, data is the currency, and servers and clients are the essential players making transactions happen. This tutorial will demystify their roles and shed light on their dynamic, ensuring you navigate the digital landscape with confidence.

Servers: The Data Powerhouses

Think of servers as the bustling supermarkets of the online world. They store vast amounts of information, waiting to be accessed by anyone with the right shopping list (client request). Whether it’s the website content you browse, your email inboxes, or even the movies you stream, servers are the reliable vendors keeping the shelves stocked.

Clients: The Data Seekers

Imagine your computer as a hungry customer, constantly searching for information you need. From sending emails to checking the weather, your computer acts as a client, sending requests to servers and eagerly awaiting their response. Clients come in all shapes and sizes, from your phone downloading an app to the software in your smart TV streaming a show.

The Intertwined Dance:

The beauty of the server-client relationship lies in its interdependence. When you type a website address, your computer (client) sends a request to a DNS server (another client!), which then directs it to the appropriate web server. This server then prepares the data you requested (HTML, images, etc.) and sends it back to your computer, satisfying your digital cravings.

Beyond the Labels:

But the world of servers and clients isn’t black and white. Sometimes, one device can play both roles simultaneously! Imagine a computer hosting a movie server for your home network. While it primarily serves data to other devices (clients), it might also be a client itself, downloading updates or accessing online resources.

The Takeaway: A Multifaceted Ecosystem

Understanding the server-client dynamic is crucial for navigating the interconnected world of technology. Remember:

• Servers provide data, clients request it.
• Both roles can exist within a single device.
• The primary function defines the label (server vs. client).

With this knowledge, you can approach any network interaction with clarity, appreciating the intricate dance of servers and clients that keeps the digital world humming.

Ready to Explore Further?

Dive deeper into the fascinating world of network roles! Learn about:

• Different types of servers (web servers, email servers, etc.)
• Client-server applications like online games and file sharing
• Security considerations for both servers and clients
• Building your own server setup at home or for small businesses

The more you understand the server-client dynamic, the more empowered you become to participate in the ever-evolving digital landscape. So, start exploring, keep questioning, and have fun!

All of the network devices
you’ve just learned about exists so that computers can
communicate with each other, whether they’re in the same room or thousands of miles apart. We’ve been calling
these devices nodes, and we’ll keep doing that. But it’s also important
to understand the concepts of
servers and clients. The simplest way to think
of a server is as something that provides data to something
requesting that data. The thing receiving the data
is referred to as a client. Well, often talk about nodes
being servers or clients. The reason our definition
uses a word as vague as something is because it’s not just nodes that can
be servers or clients. Individual computer
programs running on the same node can be servers and clients to each other too. It’s also important
to call out that most devices aren’t purely
a server or a client. Almost all nodes are both
at some point in time, quite the multitasking
overachievers. That all being said in
most network topographies, each node is primarily
either a server or a client. Sometimes we refer to an email
server as an email server, even though it’s itself a
client of a DNS server. Why? Because its
primary reason for existing is to serve
data to clients. Likewise, if a desktop
machine occasionally acts as a server in the sense that it provides data to
another computer, its primary reason for
existing is to fetch data from servers so that the user at the computer
can do their work. To sum up, a server is anything that can provide
data to a client, but we also use the
words to refer to the primary purpose of
various nodes on our network.

Welcome to the Physical Layer Crash Course!

Get ready to dive into the foundational layer of computer networks and uncover how those seemingly magical data transfers actually happen.

In this tutorial, we’ll explore:

• What is the Physical Layer?
  • Its role in the network stack model.
  • How it handles data transmission.
• Bits and Bytes: The Building Blocks
  • Understanding bits as the smallest units of data.
  • How bits form larger data structures.
• Modulation: The Language of the Physical Layer
  • Encoding bits as voltage changes on cables.
  • Different modulation techniques and their uses.
• Line Coding: The Alphabet of Communication
  • Specific methods for representing bits electrically.
  • Common line coding schemes and their characteristics.
• Network Cables: The Physical Highway
  • Types of cables used in networking (copper, fiber optic, wireless).
  • Their properties and transmission capabilities.
• Troubleshooting Physical Layer Issues
  • Identifying common problems (cable faults, signal degradation).
  • Techniques for diagnosing and resolving issues.
• Setting Up a Physical Network
  • Selecting appropriate cables and connectors.
  • Best practices for installation and maintenance.

Ready to get physical with networking? Let’s go!

In some ways, the
physical layer of our network stack model is
the most complex of all. Its main focus is
on moving ones and zeros from one end of
the link to the next. But very complicated
mathematics, physics, and electrical
engineering principles are at play to transmit huge volumes of data across tiny wires at incredible speeds. Luckily for us, most of that falls within
a different realm. With you, an aspiring IT
support specialist needs to know about the physical layer is much more approachable. By the end of this lesson, you should have a
solid foundation in aspects of the
physical layer that will allow you to
properly troubleshoot networking issues and
set up new networks. Let’s dive in. The
physical layer consists of devices and means of transmitting bits across
computer networks. A bit is the smallest
representation of data that a computer
can understand. It’s a one or a zero. These ones and
zeros sense across networks at the lowest
level are what make up the frames and
packets of data that we’ll learn about when
we cover the other layers. The takeaway is that it doesn’t matter whether you’re
streaming your favorite song, emailing your boss,
or using an ATM, what you’re really doing is
sending ones and zeros across the physical layer of the many different
networks between you, and the server you’re
interacting with. A standard copper network cable, once connected to
devices on both ends, will carry a constant
electrical charge. Ones and zeros are sent across those network cables through
a process called modulation. Modulation is a way of varying the voltage of this charge
moving across the cable. When used for computer networks, this kind of modulation is more specifically known
as line coding. It allows devices on either end of a link
to understand that an electrical charge in
a certain state is a zero and another state is a one. Through this seemingly
simple technique, modern networks are
capable of moving 10 billion ones and zeros across a single network
cable every second.

Twisted Pair Cables & Duplex Communication: Mastering Network Connections

Welcome to the world of twisted pair cables and duplex communication, the fundamental building blocks of reliable network connections! This tutorial will equip you with the knowledge to understand these essential technologies and navigate the often-tangled world of network cabling.

What are Twisted Pair Cables?

Imagine tiny data couriers zipping through a maze of wires. Twisted pair cables are those wires, made up of copper strands cleverly twisted together in pairs. This twist isn’t just for style; it’s a secret weapon against electromagnetic interference, the noisy gremlins that can disrupt data transmission. By twisting the wires, any interference picked up by one wire is canceled out by the other, ensuring your data arrives clear and strong.

More Than Just Wires: Understanding Cat Categories

Not all twisted pairs are created equal! Cables come in categories (Cat), each supporting different speeds and technologies. Cat 5e and Cat 6 are among the most common, with Cat 6a pushing the limits for gigabit speeds. Choosing the right Cat for your network is crucial for optimal performance.

Duplex Communication: A Two-Way Street

Picture a conversation where only one person can speak at a time. That’s simplex communication, like a walkie-talkie. But most networks thrive on duplex communication, where data flows in both directions simultaneously, like a lively chat room. Twisted pair cables enable this magic by dedicating specific pairs for sending and receiving, allowing devices to talk and listen at the same time.

Full Duplex vs. Half Duplex: Exploring the Speed Spectrum

Think of full duplex as a wide highway with dedicated lanes for incoming and outgoing traffic. Devices can send and receive data at blazing speeds without hiccups. Half duplex, on the other hand, is like a single-lane road where traffic takes turns going each way. It’s slower and prone to delays, but sometimes necessary due to limitations in cables or equipment.

Troubleshooting Tips: When the Connection Gets Tangled

Even the best networks can experience glitches. Knowing about twisted pairs and duplex communication can help you diagnose common issues. For example, if a network link reports half-duplex operation, it could indicate a cable fault or misconfiguration. Understanding these concepts empowers you to troubleshoot and resolve those pesky network problems like a pro!

The most common type of
cabling used for connecting computing devices is
known as twisted pair. It’s called a twisted pair
cable because it features pairs of copper wires that
are twisted together. These pairs act as a single conduit for information and
they’re twisted nature helps protect against
electromagnetic interference and cross-talk from
neighboring pairs. A standard Cat six
cable has eight wires consisting of four twisted
pairs inside a single jacket. Exactly how many
pairs are actually in use depends on the transmission
technology being used. But in all modern
forms of networking, it’s important to know that these cables allow for
duplex communication. Duplex communication
is the concept that information can flow in both
directions across the cable. On the flip side,
a process called simplex communication
is unidirectional. The way networking
cables ensure that duplex communication is possible is by reserving one or two pairs for communicating
in one direction. They then use the
other one or two pairs for communicating in
the other direction. Devices on either side
of a networking link can both communicate with each
other at the exact same time. This is known as full duplex. If there’s something wrong
with the connection, you might see a network
link to grade and report itself as
operating as half-duplex. Half-duplex means that while communication is possible
in each direction, only one device can be
communicating at a time.

Connecting the Physical Layer: A Networking Cable Crash Course

Welcome to the world of wires and lights! This tutorial will guide you through the final steps of the physical layer, where cables, plugs, and ports work together to connect your devices and ensure smooth data flow.

Plugging into the Network:

• Meet the RJ-45: Just like puzzle pieces, twisted pair cables need the right connector to fit into network ports. This is where the RJ-45, the king of network plugs, comes in. It neatly arranges the internal wires for seamless connection.
• Port Pals: Every device with network access has a port waiting for its RJ-45 buddy. Switches have many ports to connect several devices, while desktops and servers usually have one or two. Mobile devices often rely on Wi-Fi, bypassing these wired connections.

LEDs: Beacons of Connectivity:

• Link Light: This little light shines bright when a cable is connected properly and both devices are powered on. Think of it as a handshake confirming they’re ready to talk.
• Activity Light: This one blinks as data travels through the cable, like a Morse code translator revealing the digital chatter. However, in today’s high-speed networks, its rapid fire flashes become more of a general “traffic light” indicating data flow.

Beyond the Device:

• Wall Warriors: Network cables sometimes escape device confines and run through walls, connecting to ports strategically placed around your living space. These ports act as access points for your gadgets to join the network.
• Patch Panel Parade: Imagine a central hub organizing all your network cables. That’s the job of the patch panel, holding many cable endpoints and keeping things tidy. Additional cables connect the patch panel to switches or routers, distributing network access throughout your space.

Troubleshooting Tips:

• Dim Lights: A dark link light means no connection established. Check cable plugs and device power.
• Frantic Blinking: Don’t be fooled by a rapidly flashing activity light; in modern networks, it just indicates general traffic, not specific data activity.
• Port Confusion: Not all ports are created equal. Label them to avoid accidentally connecting your laptop to the server’s port!

Connecting the Dots:

Understanding how cables, plugs, ports, and LEDs work together empowers you to troubleshoot network issues and confidently navigate the physical layer. Remember, it’s all about connecting the dots, literally and figuratively, to unlock the power of your network!

So, grab your RJ-45, plug into the world of networking, and become the cable whisperer you were always meant to be!

The final steps of how the physical layer
works take place at the endpoints of our network links. Twisted pair network cables are terminated
with a plug that takes the individual internal wires and exposes them. The most common plug is known
as an RJ 45 or register Jack 45. It’s one of many cable
plug specifications, but by far the most common
in computer networking,. A network cable with an RJ 45 plug
can connect to an RJ 45 network port. Network ports are generally directly
attached to the devices that make up a computer network. Switches would have many network ports
because their purpose is to connect many devices, but servers and
desktops usually only have one or two. Your laptop, tablet or
phone probably don’t have any. Most network ports have two small L E D s. One is the link light and
the other is the activity light. The link light will be lit when a cable
is properly connected to two devices that are both powered on. The activity light will flash when data
is actively transmitted across the cable. A long time ago, the flashing of
activity light corresponded directly to the ones and zeros being sent. Today computer networks are so fast
that the activity light doesn’t really communicate much other than if
there’s any traffic or not. On switches sometimes the same LED is
used for both link and activity status. It might even indicate other
things like link speed. You’ll have to read up on a particular
piece of hardware you’re working with but there will almost always be some
troubleshooting data available to you through ports lights. Sometimes a network port isn’t
connected directly to a device. Instead, there might be network ports
mounted in a wall or underneath your desk. These ports are generally connected to the
network via cables ran through the walls that eventually end at a patch panel. A patch panel is a device containing many
network ports, but it does no other work. It’s just a container for
the endpoints of many runs of cable. Additional cables are then generally
ran from a patch panel, two switches or routers to provide network access to the
computers at the other end of those links.

Navigate the Wired World: A Crash Course in Ethernet for IT Support Specialists

Hey there, tech warriors! Feeling lost in the labyrinth of cables and connectors? No worries, this tutorial is your map to mastering the hidden language of wired networks – Ethernet. Fear not, even if you’re a networking newbie, we’ll break down the essential concepts into bite-sized pieces you can easily digest. So, grab your metaphorical soldering iron and prepare to conquer the data highways!

Why Ethernet Matters:

Forget Wi-Fi’s fickle waves, Ethernet cables are the workhorses of the network world. They silently and reliably carry data in offices, data centers, and even under the sea! That’s why understanding Ethernet is like learning the secret handshake of IT support – it’s your key to troubleshooting network mysteries and keeping the digital gears turning.

Unveiling the Data Link Layer:

Think of the network as a layered cake. Ethernet sits snugly in the Data Link Layer, its job being a trusty postman. It takes data packets from higher layers (think fancy icing decorations) and packages them for delivery via cables or fiber optic strands. But its superpower is hiding the nitty-gritty details of the physical layer (the cake pan) from the icing above. This means whether you’re using twisted pair cables or fancy lasers, your web browser doesn’t need to care – it just gets its data delivered, thanks to the magic of the Data Link Layer!

MAC Addresses: The Network IDs:

Imagine every device on the network having a unique ID card – that’s the job of MAC addresses. These 48-bit codes, like fingerprints for your network cards, tell Ethernet exactly where to send each data packet. Think of them as personalized street addresses for the digital mail system. With MAC addresses, even in crowded network hallways, your data finds its rightful recipient.

The Anatomy of an Ethernet Frame:

Picture a data packet as a letter. The Ethernet frame is its envelope, containing crucial information like the sender’s and receiver’s MAC addresses, and even a checksum to ensure the data arrives intact (like a fancy wax seal!). Understanding the frame structure helps you diagnose when things go awry in the network mailroom.

Unicast, Multicast, Broadcast: Delivering the Right Mail:

Imagine sending a letter to one person, a group chat message, or a town announcement. Ethernet has addresses for all these scenarios! Unicast is for personalized deliveries, Multicast sends to specific groups, and Broadcast shouts “Attention everyone!” Understanding these addressing modes helps you navigate the different communication channels on the network.

Collision Detection: Avoiding Network Gridlock:

Ever been stuck in a traffic jam? Ethernet has similar problems with collisions. Imagine two devices talking at the same time, creating a garbled mess! To avoid this chaos, Ethernet uses a clever trick called Carrier Sense Multiple Access with Collision Detection (CSMA/CD). It’s like a polite network etiquette, where devices listen before speaking and back off if there’s already chatter on the line. This keeps the data flowing smoothly even in busy networks.

CRCs: Ensuring Data Integrity:

Remember the checksum on the data packet envelope? That’s the Cyclic Redundancy Check (CRC), a mathematical code that detects errors like typos or missing bits during transmission. It’s like a spell-check for data, ensuring everything arrives safe and sound.

Mastering the Basics:

By understanding these core concepts, you’ll be well on your way to troubleshooting network issues like sluggish connections, dropped packets, or even the dreaded “no internet” message. You’ll be able to decipher cryptic error logs, identify faulty cables, and diagnose MAC address conflicts like a network ninja!

Remember:

Ethernet is a powerful and versatile technology that forms the backbone of wired networks. By delving into its inner workings, you equip yourself with valuable knowledge to keep the digital world humming smoothly. So, the next time you see a cable snaking its way across the office floor, remember the silent symphony of data flowing within, and feel proud knowing you understand its language!

Bonus:

• Practice identifying MAC addresses and understand their format.
• Explore tools like Wireshark to capture and analyze network traffic.
• Dive deeper into specific Ethernet types like Gigabit Ethernet or PoE (Power over Ethernet).

This is just a starting point, feel free to expand on specific topics, include real-world examples, and personalize the tutorial to keep your IT support trainees engaged and equipped to conquer the wired world!

Wireless and cellular internet
access are quickly becoming some of the most common ways to connect
computing devices to networks. And it’s probably how
you’re connected right now. So you might be surprised to hear that
traditional cable networks are still the most common option you
find in the workplace and definitely in the data center. The protocol most widely used to
send data across individual links is known as ethernet. Ethernet and
the data link layer provide a means for software at higher levels of
the stack to send and receive data. One of the primary purposes of this layer
is to essentially abstract away the need for any other layers to care
about the physical layer and what hardware is in use. By dumping this responsibility on the data
link layer, the internet transport and application layers can all operate
the same no matter how the device they’re running on is connected. So, for example,
your web browser doesn’t need to know if it’s running on a device connected via
twisted pair or wireless connection, it just needs the underlying layers
to send and receive data for it. By the end of this lesson, you’ll be able
to explain what MAC addresses are and how they’re used to identify computers. You’ll also know how to describe
the various components that make up an ethernet frame. And you’ll be able to differentiate
between Uni-Cast, multicast, and broadcast addresses. Lastly, you’ll be able to explain
how cyclical redundancy checks, help ensure the integrity
of data sent via ethernet. Understanding these concepts will
help you troubleshoot a variety of problems as an IT support specialist. Warning, a history lesson on old
school technology is headed your way. Here goes. Ethernet is a fairly old technology. It first came into being in 1980 and saw its first fully published
standardization in 1983. Since then, a few changes have been
introduced primarily in order to support ever increasing bandwidth needs. For the most part though, the ethernet in
use today is comparable to the ethernet standard as first published
all those years ago. In 1983, computer networking was
totally different than it is today. One of the notable differences in
land topology was that the switch or switchable hub hadn’t been invented yet. This meant that frequently many or all devices on a network shared
a single collision domain. You might remember from our discussion
about hubs and switches that a collision domain is a network segment where
only one device can speak at a time. This is because all data in
a collision domain is sent to all the nodes connected to it. If two computers were to send data
across the wire at the same time, this would result in literal collisions of
the electrical current representing our ones and zeros,
leaving the end result unintelligible. Ethernet as a protocol solve this
problem by using a technique known as carrier sense multiple
access with collision detection. Doesn’t exactly roll off the tongue. We generally abbreviate this to CSMA CD. CSMA CD is used to determine when
the communications channels are clear and when the device is free to transmit data. The way CSMA CD works is
actually pretty simple. If there’s no data currently being
transmitted on the network segment, a node will feel free to send data. If it turns out that two or
more computers end up trying to send data at the same time, the computers detect
this collision and stop sending data. Each device involved with
the collision then waits a random interval of time before
trying to send data again. This random interval, helps to prevent all
the computers involved in the collision from colliding again the next time
they try to transmit anything. When a network segment is a collision
domain, it means that all devices on that segment receive all
communication across the entire segment. This means we need a way to identify
which node the transmission was actually meant for. This is where something known as
a media access control address or MAC address comes into play. A MAC address is a globally
unique identifier attached to an individual network interface. It’s a 48-bit number
normally represented by six groupings of two hexadecimal numbers. Just like how binary is a way to
represent numbers with only two digits. Hexadecimal is a way to represent
numbers using 16 digits. Since we don’t have numerals to represent
any individual digit larger than nine, hexadecimal numbers employ the letters A,
B, C, D, E and F to represent the numbers 10,
11, 12, 13, 14 and 15. Another way to reference each group of
numbers in a MAC address is an octet. In octet, in computer networking is any
number that can be represented by 8-bits. In this case, two hexadecimal digits can represent
the same numbers that 8-bits can. Now, you may have noticed that we
mentioned that MAC addresses are globally unique, which might have left you
wondering how that could possibly be. The short answer is that a 48-bit number
is much larger than you might expect. The total number of possible MAC addresses that could exist is two
to the power of 48 or 281,474,976,710,656 unique possibilities. That’s a whole lot of possibilities. A MAC address is split into two sections. The first three octets of
a MAC address are known as the organizationally unique identifier or
OUI. These are assigned to individual
hardware manufacturers by the IEEE or the Institute of Electrical and
Electronics Engineers. This is a useful bit of information to
keep in your back pocket because it means that you can always identify the
manufacturer of a network interface purely by its MAC address. The last three octets of a MAC address
can be assigned in any way that the manufacturer would like,
with the condition that they only assign each possible address once to keep
all MAC addresses globally unique. Ethernet uses MAC addresses to ensure that
the data it sends has both an address for the machine that sent the transmission,
as well as, the one that the transmission
was intended for. In this way, even on a network segment
acting as a single collision domain, each node on that network knows
when traffic is intended for it.

Exploring the Neighborhood: Unicast, Multicast, and Broadcast in Ethernet

In the bustling world of Ethernet, data zips between devices, carrying information that keeps the digital realm humming. But how does this information reach its intended recipient? It all boils down to different transmission types, each with its own unique delivery method. Buckle up, network adventurers, as we embark on a journey through Unicast, Multicast, and Broadcast – the three musketeers of Ethernet communication!

Unicast: The One-on-One Conversation

Imagine whispering a secret to a friend in a crowded room. Your message, like an Ethernet frame, is meant for only one pair of ears. This targeted delivery is the domain of Unicast transmission.

• How it works: The destination MAC address acts as the secret handshake. If the least significant bit in the first octet is 0, it’s a Unicast frame whispering to a specific device.
• Think of it as: Sending a private email or making a direct phone call.
• Benefits: Ensures secure and confidential communication between two devices.

Multicast: Group Chat for the Network

Now, picture hosting a lively discussion with a group of friends. You want everyone to hear your thoughts, but not strangers eavesdropping. Multicast transmission takes care of this group communication on the network.

• How it works: Similar to Unicast, the destination MAC address tells the story. This time, a 1 in the least significant bit of the first octet identifies a Multicast frame meant for a specific group.
• Think of it as: Sending a group message or hosting a video conference with invited participants.
• Benefits: Efficiently delivers information to a specific group of devices without flooding the entire network.

Broadcast: Town Crier in the Digital Age

Remember the town crier shouting announcements in the old days? Broadcast transmission takes on this role in the Ethernet world, sending a message to every single device on the network, like a digital town hall.

• How it works: No need for fancy addresses here. Broadcast frames use a special destination address – all F’s – like a universal bullhorn.
• Think of it as: Making a public announcement or sending a system-wide alert.
• Benefits: Useful for device discovery, network announcements, and system-wide updates.

Choosing the Right Tool for the Job:

Understanding these transmission types empowers you to make informed decisions about network communication. Unicast for confidential exchanges, Multicast for targeted group discussions, and Broadcast for reaching the entire digital neighborhood – choose wisely, network warriors!

Bonus Round:

• Explore advanced Unicast variations like Directed Broadcasts and Gratuitous Arps.
• Dive deeper into Multicast protocols like IGMP (Internet Group Management Protocol).
• Discover real-world applications of each transmission type in different network scenarios.

By mastering these concepts, you’ll navigate the intricate highways of Ethernet communication with confidence, ensuring smooth data flow and a thriving digital ecosystem!

Remember, the key is to choose the right transmission type for the task at hand. With this knowledge in your arsenal, you’ll be the neighborhood wizard, orchestrating the flow of information with precision and finesse!

So far, we’ve discussed ways for one device to transmit
data to one other device. This is what’s known as unicast. A unicast transmission is always meant for just one
receiving address. At the ethernet level
this is done by looking at a special bit in the
destination MAC address. If the least significant bit in the first octet of a destination
address is set to zero, it means that ethernet frame is intended for only the
destination address. This means it would be sent to all devices on the
collision domain, but only actually received and processed by the
intended destination. If the least significant bit in the first octet of a destination
address is set to one, it means you’re dealing
with a multicast frame. A multicast frame is similarly set to all devices on the
local network segment. What’s different is that it will be accepted or discarded by each device depending on criteria aside from their
own hardware MAC address. Network interfaces can
be configured to accept lists of configured
multicast addresses for these sorts of
communications. The third type of
ethernet transmission is known as broadcast. In ethernet, broadcast is sent to every single
device on a LAN. This is accomplished by using a special destination known
as a broadcast address. The ethernet broadcast
address is all F’s. Ethernet broadcasts are used so that devices can learn
more about each other.

Unveiling the Secrets of the Ethernet Frame: A Crash Course for Tech Warriors

Hey there, network adventurers! Ever wondered how data zips and zags across wires and fiber strands, connecting you to the digital world? It all boils down to the silent heroes of network communication – Ethernet frames! These structured bundles of information carry the lifeblood of the internet, from cat videos to critical business transactions. In this crash course, we’ll crack open the Ethernet frame, revealing its secrets and empowering you to understand the language of the network.

Think of data as letters: Imagine each piece of information you send online, from emails to memes, as a letter. But instead of envelopes, these letters travel in special packages called data packets. Now, in the bustling marketplace of network protocols, Ethernet reigns supreme. Its packets, known as Ethernet frames, follow a meticulous structure, ensuring smooth delivery and reliable communication.

Dissecting the Frame: Picture the Ethernet frame as a letter with distinct sections, each serving a crucial purpose:

• Preamble: This eight-byte intro acts like a friendly knock on the network door, alerting devices that data is incoming.
• Start Frame Delimiter (SFD): This single byte, like a doorbell chime, signals the start of the actual message.
• Destination and Source MAC Address: These 48-bit codes, like unique street addresses, tell the network where the letter is going and where it came from.
• Ether-type: This 16-bit identifier reveals the letter’s content type, whether it’s an email (IP), a video call (UDP), or something else entirely.
• Data Payload: This is the meat of the matter, carrying the actual data, from funny cat gifs to urgent business reports. (Size: 46-1500 bytes)
• Frame Check Sequence (FCS): This 32-bit code acts like a checksum, ensuring the letter arrived intact by catching any sneaky typos or missing bits.

Why It Matters: Understanding the structure and purpose of each frame component equips you with superpowers to troubleshoot network issues. Imagine a dropped letter – a corrupted frame! By analyzing the FCS, you can identify the culprit, whether it’s a faulty cable or a mischievous gremlin in the network closet.

Beyond the Basics:

This is just the tip of the Ethernet frame iceberg! As you delve deeper, you’ll discover:

• VLANs: Imagine dividing your apartment building into separate floors for different tenants. VLANs do the same for network traffic, creating logical sub-networks within a physical one.
• Giant Frames: Need to send extra-large letters, like movie files? Jumbo frames expand the data payload capacity for faster transfers.
• 802.1Q Tagging: Think of this as a colored sticker on your letter, indicating which VLAN it belongs to for smooth delivery within the building.

Mastering the Frame:

By understanding the fundamentals of Ethernet frames, you’ll become a network whisperer, deciphering the secret language of data communication. You’ll be able to diagnose connectivity issues, optimize network performance, and even impress your friends with your newfound knowledge of the digital highways. So, the next time you see a blinking network light, remember the silent symphony of Ethernet frames flowing within, and feel proud knowing you speak their language!

Remember: This is just a starting point! Feel free to explore specific frame variations, delve deeper into advanced protocols, and practice dissecting real-world frame captures. With dedication and curiosity, you’ll become a true master of the Ethernet frame, a champion of the digital realm!

To wrap up, we’ll round
out your understanding of the basics of networking by
dissecting an Ethernet frame. Understanding the
networking basics is the first step in building a really strong foundation of networking knowledge that
you’ll need in IT support. A data packet is an all-encompassing
term that represents any single set of binary data being sent across
a network link. The term data packet isn’t tied to any specific
layer or technology, it just represents a concept, one set of data being sent
from point A to point B. Data packets at
the Ethernet level are known as Ethernet frames. An Ethernet frame is a highly structured
collection of information presented
in a specific order. This way, network interfaces at the physical layer
can convert a stream of bits traveling across a link into meaningful
data or vice versa. Almost all sections of an
Ethernet frame are mandatory, and most of them
have a fixed size. The first part of
an Ethernet frame is known as the preamble. A preamble is eight
bytes or 64 bits long, and can itself be split
into two sections. The first seven
bytes are a series of alternating ones and zeros. These act partially as a buffer between frames and
can also be used by the network interfaces to synchronize internal clocks they use to regulate the speed
at which they send data. This last byte in the
preamble is known as the SFD, or start frame delimiter. This signals to a receiving
device that the preamble is over and that the actual frame
contents will now follow. Immediately following the
start frame delimiter, comes the destination
MAC address. This is the hardware address
of the intended recipient, which is then followed
by the source MAC address or where the
frame originated from. Don’t forget that
each MAC address is 48 bits or six bytes long. The next part of
an Ethernet frame is called the Ether-type field. It’s 16 bits long and used to describe the protocol of
the contents of the frame. We’ll be doing a
deep dive on what these protocols are
a little later. It’s worth calling out that instead of the Ether-type field, you can also find what’s
known as a VLAN header. It indicates that the frame itself is what’s
called a VLAN frame. If a VLAN header is present, the Ether-type field follows it. VLAN stands for virtual LAN. It’s a technique
that lets you have multiple logical LANs operating on the same physical equipment. Any frame with a VLAN tag
will only be delivered out of a switch interface configured
to relay that specific tag. This way, you can have a single physical network that operates like its multiple LANs. VLANs are usually used to segregate different
forms of traffic. You might see a company’s
IP phones operating on one VLAN while all
desktops operate on another. After this, you’ll find the data payload of
an Ethernet frame. A payload in networking terms is the actual data
being transported, which is everything
that isn’t a header. The data payload of a
traditional Ethernet frame can be anywhere from
46-1500 bytes long. This contains all of the
data from higher layers, such as the IP, transport, and application layers that
actually being transmitted. Following that data,
we have what’s known as a frame check sequence. This is a four-byte
or 32-bit number that represents a checksum
value for the entire frame. This checksum value is
calculated by performing what’s known as a cyclical redundancy check
against the frame. A cyclical redundancy
check, or CRC, is an important concept for data integrity and is
used all over computing, not just network transmissions. A CRC is basically a mathematical
transformation that uses polynomial division to create a number that represents
a larger set of data. Anytime you perform a CRC
against a set of data, you should end up with
the same checksum number. The reason it’s included in
an Ethernet frame is so that the receiving network
interface can infer if it received
uncorrupted data. When a device gets ready
to send an Ethernet frame, it collects all the
information we just covered, like the destination and
originating MAC addresses, the data payload, and so on. Then it performs a CRC against
that data and attaches the resulting checksum number as the frame check sequence
at the end of the frame. This data is then sent across a link and received
at the other end. Here, all the various fields of the Ethernet
frame are collected, and now the receiving side performs a CRC
against that data. If the checksum computed
by the receiving end doesn’t match the checksum in the frame check
sequence field, the data is thrown out. This is because
some amount of data must have been lost or
corrupted during transmission. It’s then up to a protocol at a higher layer to decide if that data should
be retransmitted. Ethernet itself only
reports on data integrity, it doesn’t perform
data recovery. You’ve gotten the basics of
networking now, nice work.

[MUSIC]
If you are interested in IT and you never went to school for it. You don’t have a CS degree,
anything like that. I always tell people that half the people
that I’ve worked with a google do not have a traditional IT background. I’ve worked with people
in IT who were teachers, I knew people that were drama majors,
that were history majors, chemist. It has nothing to do with it, right? It’s all about being able
to connect with people, being able to look at a problem and break
it down into components that are each pretty easy to solve on the road
until you get the whole thing solved. That’s it, right,
learning the technical piece is easy, anyone can learn that piece. For one, I tell them like just
go get your hands dirty, right? There’s a lot of places where
you can kind of just go and do this even at home, right? You probably have a wireless network or
something, go break it, right, go do that, get your hands dirty, try it out. Set up a virtual machine and go and
break it 100 different ways, and then figure out all the different
ways you can fix it. It’s going to give you the most
practical experience into it. You’re going to figure out whether finding
the problems is actually something that gets you excited, cool I figured this out. It’ll tell you whether this is
like the right field for you. I wouldn’t be dissuaded just because
you don’t think you have a technical background. The technical background piece
is the least important piece.