How does the internet work? The video you are watching now traveled thousands of miles from a Google Data Center to reach
you. Let's learn how the internet works by getting to understand the details of
this data's incredible journey. The data center which can be thousands of miles away from you has your video stored inside it. how does this data reach your mobile phone or a laptop? An easy way to achieve this goal would be with use of satellites. From the data center, a signal could be
sent to the satellite via an antenna, and then from the satellite a signal
could be sent to your mobile phone via another antenna near to you. However, this way of transmitting signals is not a good idea. Let's see why. The satellite is parked nearly 22,000 miles above the earth's equator, so in order for the data transmission to be successful, the data would have to travel a total distance of 44,000 miles. Such a long distance of travel causes a
significant delay in receiving the signal. More specifically it causes huge
latency which is unacceptable for most internet applications so if this video does not reach you via a satellite then how does it actually get to you? Well it is done with the help of a complicated network of optical fiber cables, which connect between the data center and your device. Your phone could be connected to the
internet via cellular data or any Wi-Fi router, but ultimately at some point your
phone will be connected to this network of optical fiber cables We saw at the beginning that the video
you are currently watching is stored inside a data center. To be more specific, it is stored in a
solid-state device within the data center. This SSD acts as the internal memory of a server. The server is simply a powerful computer
whose job is to provide you the video or other stored content when you request it. Now the challenge is how to transfer the data stored in the data center specifically to your device via the complex network of optical fiber cables. Let's see how this is done. Before proceeding further we should first
understand an important concept which is the concept of an IP address. Every device that is connected to the Internet whether it is a server a computer or a
mobile phone is identified uniquely by a string of numbers known as an IP address. You can consider the IP address similar to your home address that is the address,
that uniquely identifies your home. Any letter sent to you reaches you precisely because of your home address. Similarly in the internet world an IP
address acts as a shipping address through which all information reaches
its destination. Your internet service provider will decide the IP address of your device and you are able to see what IP address your ISP has given to your
mobile phone or laptop. The server in the data center also has
an IP address. The server stores a website so you can
access any website just by knowing the server's IP address. However, it is
difficult for a person to remember so many IP addresses. So to solve this problem domain names like youtube.com, facebook.com etc are used which correspond to IP addresses which are easier for us to remember than the long sequence of numbers Another thing to notice here is that a server has the capability of storing several websites and if the server consists of multiple
websites all the websites cannot be accessed with the server's IP address. In such cases additional pieces of information, host headers are used to
uniquely identify the website. However, for the giant web sites like Facebook.com or YouTube.com the entire data center infrastructure will be dedicated
to the storage of the particular website. To access the internet we always use
domain names instead of the complex IP address numbers. From where does the internet get IP addresses corresponding to our domain name requests. Well, for this purpose the internet uses a huge phone book known as DNS. If you know a person's name, but don't know their telephone number you can simply look it
up in a phone book. The DNS server provides the same service to the internet. Your internet service provider or other organizations can manage the DNS server. Let's have a recap of the whole operation. You enter the domain name, the browser sends a request to the DNS
server to get the corresponding IP address. After getting the IP address, your browser simply forwards the request to the data center, more specifically to the respective
server. Once the server gets a request to access
a particular website the data flow starts. The data is transferred in digital format via optical fiber cables, more specifically in the form of light
pulses. These light pulses sometimes have to travel thousands of miles via the
optical fiber cable to reach their destination. During their journey they often have to go through tough terrains such as hilly areas or under the sea. There are a few global companies who lay and maintain these optical cable
networks. These visuals show how the laying of optical fiber cables is done with the help of a ship. A plow is dropped deep into the sea from
the ship, and this plow creates a trench on the
seabed and to which places the optical fiber cable. In fact, this complex optical cable network is the backbone of the Internet. These optical fiber cables carrying the light are stretched across the seabed to
your doorstep where they are connected to a router. The router converts these light signals to electrical signals. An Ethernet cable is then used to transmit the electrical signals to your
laptop. However if you are accessing the Internet using cellular data, from the optical cable the signal has to be sent to a cell tower and from the cell tower the signal reaches your cell phone in the form of
electromagnetic waves. Since the Internet is a global network
it has become important to have an organization to manage things like IP
address assignment, domain name registration etc this is all managed by
an institution called ICANN located in the USA. One amazing thing about the
internet is its efficiency in transmitting data when compared with
cellular and landline communication technologies. This video you are watching
from the Google Data Center is sent to you in the form of a huge collection of
zeros and ones. What makes the data transfer in the internet efficient is the way in which these zeros and ones are chopped up into small chunks known
as packets and transmitted. Let's assume these streams of zeros and ones are divided into different packets by the server where each packet consists of six
bits. Along with the bits of the video each
packet also consists of the sequence number and the IP addresses of the
server and your phone. With this information the packets are routed towards your phone. It's not necessary that all packets are routed through the same path and each packet independently takes the best route available at that
time. Upon reaching your phone the packets are reassembled according to their sequence number. If it is the case that any packets fail to reach your phone and acknowledgement is sent from your phone to resend the lost packets. Now compare this with a postal network with a good infrastructure, but the
customers do not follow the basic rules regarding the destination addresses. In this scenario letters won't be able to reach the correct destination. Similarly in the internet we use
something called protocols for the management of this complex flow of data
packets. The protocols set the rules for data packet conversion, attachment of the source and destination addresses to each packet and the rules for routers etc for
different applications the protocols used are different. We hope this video has given you a good understanding about how the internet
works, more specifically about the amazing journey of data packets from the data center to your mobile phone. Please don't forget to support us at
patreon.com. Thank You!
