Introduction to Computer Networking

Networking is a way through which many computers talk to each other and to the world.

What is Internet?

You may know this but who is guessing it as a web browser,
For those NO, the internet is not a web browser. A web Browser is
software that let us access part of the public internet using “www” or “World Wide Web“.
There are still more than this that use the internet like
FTP, BitTorrent, Movie Streaming, and some others.

The Internet is a series of system devices which is connected globally and publicly. And all the responses and requests are happens through these devices.

There is also the term intranet which you will hear often.
It means when devices are connected in order to privately share requests and responses.

The use of “VPN” is an example of the intranet.
It keeps the devices safe and restricts accessing
the network (collection of devices) publicly.

Protocols on the Internet

To work this massive system requires some standard protocols.
With time many people created these and everyone follows these protocols. We will look into some of these.

IP (Internet Protocol)

It means that data sharing on the web is structured
well enough so that receiver and sender devices know how to read, write and send it back to keep it going.

IP Address

It is a unique address assigned to each device that connects to the internet.

IPv4 vs IPv6

Initially, there were fewer devices that could access the internet.
So, to provide every device a separate IP Address that looks something like “8.8.8.8” there was
the creation of IPv4 which can handle nearly 4 million devices.

BUT BUT BUT after a few years, the number of devices
that connects to the internet kept increasing, and then
there is the development of IPv6, which can
handle more than trillions may be bazillion devices.
And it looks something like “2000:4890:4890:8888”.

TCP (Transfer Control Protocol)

It is a protocol that helps in transferring data without losing anything. Before sending data, It confirms if the device at the receiving end is active and accepting data.
And after that, it starts sending data to the receiver using this protocol, and it’s safe and guarantees data transfer.

UDP (User Datagram Protocol)

UDP is like broadcasting, It just sends data to the receiver device.
It doesn’t care if other devices got the data or not. That’s why it’s faster than TCP.

Domain Name

Remember IP addresses, The problem with IP Addresses
is these are collections of numbers.
Let’s say you want to connect to Google or Twitter, Technically these services have servers and it has its IP Addresses.
But it will be very very difficult to remember IP Addresses, that’s where comes in “Domain Name”.
Domain names are unique and easily remembered in comparison to IP Addresses.

DNS (Domain Name System)

It is an ICANN-managed system. ICANN helps in keeping this system safe, robust, and stable.
DNS is an intelligent phonebook of the internet. Because it keeps track of which domain name has which IP Address,
and manages to optimize the responses to the requests.

HTTP (Hypertext Transfer Protocol)

HTTP is a protocol that helps in sharing HTML Files on the web.
HTML files contain text, images, documents, videos, and more.
So, HTTP follows Client-Server Architecture to send responses to requests. And the under the hood it uses TCP to complete the operation of transferring HTML files all over the web.

HTTPS (Hypertext Transfer Protocol Secure)

HTTPS does the same thing as HTTP but securely.
Because in HTTP any middle person can steal the data when
two computer devices were sharing data without knowing about it.
It can lead to stealing information like credit card details and things like that.
In simple terms, HTTPS is encrypted on the client (user) side and decrypted on the server side (who responds to requests).

Computer Networks

Now to create a system that is ready to connect all
the computer devices in the world with networking concepts.
To expand in the area to make the internet accessible to everyone, different types of networks are created.

LAN (Local Area Network)

LAN covers areas like a house, a building, or something like that.
The common devices to cover this much range is ethernet and WiFi routers. These help in connecting devices within this area.

PAN (Personal Area Network)

PAN covers even less area than LAN. Using Mobile hotspots to connect different devices is an example of a PAN.
It is very simple to set up, but it is limited in number of connected devices and range.

MAN (Metropolitan Area Network)

MAN covers a range of the whole city. It covers this much area because so many LANs connect to each other.
WiMax and Television Cables are examples of MAN.

WAN (Wide Area Network)

It covers the range from country to country at a global scale.
Connecting multiple MANs creates a WAN.

Network Structure

Bringing different types of devices under a network requires
a structure that is said as Network Topology. These can be of many types, we are gonna look into these.

Bus Topology

In this topology, every computer is connected to a single cable.
Devices can send data one at a time.

Benefits

• It is easy to set up and connect devices.
• The cost of setting up is not too much

Drawback

• It can be slow because of sending data one at a time.
• If there is an issue in one device, It can stop the whole network.

Ring Topology

This is like Bus Topology but its ends are closed. By closing the network every device will act like a networking node. And because of this data goes through every node.

Benefits

• It can handle heavy loads of data to transfer as compared to Bus Topology.
• If there is any issue in the network it will be easy to identify because of which node it happened.

Drawbacks

• Data transfer can be slow because multiple devices share the same bandwidth.
• If one node is facing an issue, we have to take the whole networking setup offline to fix it.

Star Topology

Every device is linked to a single node, which acts as a hub.
Hub manages everything, including which data goes to
which device to traffic management between all these devices.
And it is the best network topology.

Benefits

• Every device is free from other devices, So even if one fails, no one is affected.
• The issue can be fixed without shutting down the whole networking setup.

Drawbacks

• If the hub fails then the whole system will be shut down.
• The speed of data transfer depends on how much load the hub can take. If Hub is not good enough and the load is too much then data transfer will end up happening slowly.

Mesh Topology

Every device in this setup connected to other devices
directly without any central devices. This makes mesh very efficient in data transfer.

Benefits

• Data can be shared very fast.
• Very less chance of failing a node.

Drawbacks

• There is too much use of cables which makes this networking setup very costly.
• To set up this every computer has to connect with each device. It makes it less scalable.

Hybrid Topology

In this type, there can be the use of two or more types of topologies to handle file and data sharing. It can be completely customised to meet your requirements.

Benefits

• It depends on the type of topologies that are merging.
• But the setup will likely be customized, So there might be
  less chance of failure because it is customized for some specific need.

Drawbacks

• Things may get complex while fixing issues.
• Every topology comes with its disadvantages. And combining different topologies will come with its own set of disadvantages.

OSI Model

OSI Model stands for Open System Interconnection Model.
This model has 7 layers of which some represent physical work and some are software. This is very important part of networking structure.
The goal is that after getting a request from the user
it helps in responding with results securely and efficiently. Here are these 7 layers that make it possible.

1. Physical Layer – This is the lowest layer, in this layer
   all the physical components exist like cables, optical fiber, and many things. The processing of data into signals happens in this layer.
   
2. Data Link Layer – In this layer the structure of data is defined. It makes sure that data gets to the “Network layer” without any error
   
3. Network Layer – This layer uses a device like a router and decides which path data should take to go to the next layer.
   
4. Transport Layer – This layer breaks down data into small bits and sends it to Network Layer. Data is taken from Session Layer and then goes to Transport Layer.
   
5. Session Layer – This layer keeps the devices in sync so
   that data can transfer successfully and securely.
   
6. Presentation Layer – It receives the data and converts it
   in such a format that the Application Layer can process it. And Data Encryption and Decryption happen in this layer.
   
7. Application Layer – This is the topmost layer of the OSI Model, It is the interface part of the model.
   In this layer, users send request mail, image, video, or any data.

Conclusion

• The computer network is a collection of connected computers at different scales.
• The Internet is working on the principles of networking.
  It has a set of protocols like FTP, HTTPS, TCP/IP, and many more that keep it safe, reliable, and accessible for everyone.
• There are different types of computer networks like PAN, LAN, MAN, and WAN.
• Topologies have their own benefits and drawbacks.
• These Topologies are Bus, Start, Ring, Mesh, and Hybrid Topology.
• At last, we looked into how OSI Model uses physical devices and software to get requests and deliver responses in the networking structure.
• The 7 layers of the OSI model are Physical, Data Link,
  Network, Transport, Session, Presentation, and Application Layer.