From the Ocean Floor to Your Browser: The Internet's Journey

We are going to understand the network from very scratch,
Who is the owner of it?
How does it available to us?
How many devices are included to make this possible?

Go let’s start the trip “From Wires to Web”

Deep Blue Origin (Undersea Cables & AS)

Undersea wires (Fiber Optics Cables) are backbone of network. Large organizations manage them, like Tata Communication (they connects 240+ countries and territories, own major share of global backbone traffic).

Autonomous Systems (AS) is a network under one single administrative control, identified by an unique Autonomous System Number (ASN) and using the Border Gateway Protocol (BGP) to exchange the routes.

What do AS (Autonomous Systems) do ?

They have there own network through wires or rent wires.
Tier-1 ASes don’t buy internet from anyone.
They do Peering (free or settlement-free), Paid peering, Transit (paid), exchange of routes.
They reach to whole world and connects they world

Examples of Tier-1 ASes (Autonomous Systems):
Tata Communications
AT&T
Verizon
NTT

Border Control (BGP & ISP)

Finally, cable hits land. But still they need to know where to go next.
This is where Border Gateway Protocol (BGP) comes in picture.
The Border Gateway Protocol (BGP), exchanges routing information between Autonomous Systems to determine the best path for traffic. BGP allows ASes to interconnect.

An ISP provides last-mile connectivity and IP routing services to end users, connecting customer networks to the global Internet.

Wires bring data from different sources under oceans to land, Then BGP helps to decides the paths data should take between networks.
BGP decides where data should go, but time to send that data to real user. So ISP comes in, helps route data to particular address.

Modem / ONT

ISP wire (fiber or copper) reach to your home. Copper/coax and Fiber cables carries electrical / RF and optical signals, but devices speak digital data.
This problem is solved by the Modem/ONT. Modem/ONT do signal conversion, they translate signals.

Demodulation: Incoming signals from cable gets converted into digital data usable by the home network.
Modulation: Device sends back the digital data, digital data gets converted into analog/optical signals.

Modem VS ONT (Optical Network Terminal):
Modem do modulation and demodulation and ONT do signal conversion. Works on different technologies.
Modem: Handles copper wire / coax cable. These cables bring electrical / RF signals, modem converts that into digital data.
ONT: Handles Fiber optics cable. These cables bring light signals, ONT converts that into digital data.

Router

Once digital data enters the home through the Modem or ONT, it reaches the Router.
The router acts as the boss of the home network, deciding how data should flow between devices and the Internet.
Router connects two different networks:

The external network (ISP / Internet)
The internal network (your home LAN)

What does a Router do?
The router share data packets between networks using the IP addresses.

• Incoming Data : Routed to the correct device.

• Outgoing Data : Routed to internet.

For assigning the IP address and routing the data packets to the particular address, The NAT(Network Address Translation) and DHCP(Automatic IP Assignment) are responsible.

NAT (Network Address Translation)
Home devices use private IP addresses that are not visible on the Internet.

• Router replaces private IPs with one public IP

• Keeps a translation table to send responses back to the correct device

NAT allows multiple devices to share a single Internet connection

DHCP (Automatic IP Assignment)
Instead of manually assigning IPs to every device:

• Router runs a DHCP server

• Automatically assigns:

  • IP address

  • Subnet mask

  • Gateway

  • DNS

“Wi-Fi connect ho gaya” = DHCP succeeded

Switch vs. Hub

Hub (Old Technology)

• Sends incoming data to every connected device

• No intelligence, no filtering

• Causes collisions and wasted bandwidth

Result: Slow and inefficient

Switch (Modern Technology)

• Sends data only to the destination MAC address

• Learns which device is on which port

• Reduces collisions and improves performance

Result: Fast and efficient

Firewall

Once the traffic passes the Router, we need security. The Internet is full of malicious requests, hackers, and bots. A Firewall is a network security device that monitors incoming and outgoing network traffic and decides whether to allow or block specific traffic based on a defined set of security rules.

What does a Firewall do?

• Packet Filtering: It inspects data packets. If a packet comes from a suspicious IP or tries to enter a blocked Port, the Firewall rejects it.

• Stateful Inspection: It remembers active connections. If you didn't ask for a video, it won't let a random video stream enter your network.

Load Balancer

Now, let's look at the other side, where the website lives (like Google or Netflix). When millions of users hit a website at the same time, one single server cannot handle the pressure. It will crash. A Load Balancer acts as a "traffic cop" sitting in front of your servers and distributing client requests across all servers capable of fulfilling those requests.

Why do we need it?

It ensures no single server bears too much demand.

If one server goes down, the Load Balancer detects it and redirects traffic to the remaining online servers.

Conclusion, The Full Journey

So, that is the physical journey of the Internet

1. Deep Sea: Data travels through Undersea Cables.

2. Border: BGP decides the route between countries.

3. Entry: Modem/ONT translates the signal (Light/Analog to Digital).

4. Distribution: Router assigns an IP and directs the packet.

5. Security: Firewall checks if the packet is safe.

6. Delivery: Switch delivers it to your specific device.

Now that we are connected physically, there is one big problem left. Computers don't speak English. They don't know what google.com is, they only know IP addresses like 142.250.1.1.

So, how does your browser translate a name into an IP address? That is where the Phonebook of the Internet (DNS) comes in.