Learning Objectives

By the end of this chapter, you will be able to:

  • Describe the internet backbone.
  • Explain the role of an Internet Service Provider (ISP).
  • Identify TCP/IP as the core protocol of the internet.
  • Explain packet switching, IP addresses, domain names, and DNS.
  • Trace what happens when a customer opens an online shop.
  • Describe Nepal’s internet infrastructure and its weak points.

The Internet Architectural Hierarchy

The Internet’s infrastructure is not a single entity but a layered system of technologies that work together. It can be viewed as a four-layer architecture:

  1. Layer 1: Network Technology Substrate: The physical hardware (fiber-optic cables, routers, satellites, and switches).
  2. Layer 2: Transport Services and Middleware: The protocols (TCP/IP) that govern how data moves.
  3. Layer 3: Applications: The services we use (Web, E-mail, VoIP).
  4. Layer 4: Users: The individuals and businesses participating in the network.
flowchart TB
  L4[Layer 4: Users] --> L3[Layer 3: Applications]
  L3 --> L2[Layer 2: Transport / TCP-IP]
  L2 --> L1[Layer 1: Network Technology Substrate]
  L1 --> Fiber[Fiber-optic Backbone]
  L1 --> IXP[Internet Exchange Points]
  L1 --> LastM[Last Mile Access]
  LastM --> FTTH[FTTH]
  LastM --> Mobile[4G / 5G]
  LastM --> Sat[Satellite]

Figure 1: Four-layer Internet architecture and access paths

1. The Internet Backbone (Tier 1 ISPs)

The backbone consists of high-bandwidth fiber-optic cable networks spanning continents and oceans.

  • Backbone Providers: Large companies (like AT&T, Verizon, Tata Communications) own these “Tier 1” networks.
  • Peering: Backbone providers connect with each other for free to exchange traffic.
  • Transit: Regional ISPs pay Tier 1 providers for access to the global backbone.

2. Internet Exchange Points (IXPs)

An IXP is a physical hub where different ISPs and content providers (like Google or Netflix) connect their networks to exchange traffic locally.

  • Benefit: Reduces costs and latency by keeping local traffic within the country rather than routing it through international links.

3. The Last Mile (Client Access)

The “Last Mile” refers to the final leg of the connection between the ISP and the end-user’s home or office. Common technologies include:

  • FTTH (Fiber to the Home): The fastest and most reliable (predominant in urban Nepal).
  • Mobile Wireless: 4G/LTE and 5G networks.
  • Satellite: Used for remote areas where cables cannot reach.
  • DSL/Cable: Older technologies using copper telephone or TV lines.
Access type Typical speed Strengths Limitations
FTTH (fibre) High, stable Fast, low latency, unlimited plans Needs cable to the building
4G / 5G mobile Medium to high Available almost anywhere, mobile Data costs, coverage gaps in hills
Satellite Low to medium Reaches remote areas Expensive, higher latency, weather affects
DSL (copper) Low Uses existing phone lines Slow, being replaced by fibre

4. Packets and TCP/IP in Brief

The previous chapter explains packet switching and the four TCP/IP layers. In short, data travels as small packets that routers forward independently. IP gives every device an address and routes each packet towards it, and TCP makes sure all packets arrive and are put back in order. The application layer on top (HTTP, email, DNS) is what e-commerce sites and customers actually use.

5. IP Addresses, Domain Names, and DNS

Every device on the Internet needs an IP address.

  • IPv4 addresses are 32-bit numbers written as four parts, such as 192.0.2.10. There are about 4.3 billion of them, which is no longer enough.
  • IPv6 addresses are 128-bit and written in hexadecimal, such as 2001:db8::1. They provide an almost unlimited number of addresses.

People do not remember numbers, so websites use domain names such as daraz.com.np. The Domain Name System (DNS) is a distributed directory that translates domain names into IP addresses. A URL (Uniform Resource Locator) such as https://www.example.com.np/products/bag combines the protocol, the domain name, and the path to a specific page.

In Nepal, .np domain names are managed by Mercantile Communications, and registration of a .com.np name for a Nepali business or person is free with supporting documents.

6. Worked Example: Opening an Online Shop from Pokhara

A customer in Pokhara on a fibre connection types daraz.com.np into a browser.

  1. DNS lookup: The browser asks a DNS server for the IP address of daraz.com.np. The ISP’s DNS server often has the answer cached.
  2. Connection: The browser opens a TCP connection to that IP address and sets up HTTPS encryption.
  3. Request: The browser sends an HTTP request for the home page.
  4. Routing: Packets travel from the customer’s router to the ISP, and then either to a server inside Nepal (often through NIXP or a local cache) or over international links through India or China to a data centre abroad.
  5. Response: The server sends back HTML, images, and scripts as many packets; TCP reassembles them and the page appears.

If the shop’s images are served from a content delivery network (CDN) with a cache inside Nepal, the page loads faster and uses less expensive international bandwidth. This is why large e-commerce sites care about where their content is hosted.

flowchart LR
    U[Customer browser] -->|1. Where is daraz.com.np?| DNS[DNS server]
    DNS -->|IP address| U
    U -->|2-3. HTTPS request| ISP[Local ISP]
    ISP --> IX[NIXP or local cache]
    ISP --> INTL[International link via India or China]
    IX --> S[Web server or CDN]
    INTL --> S
    S -->|5. Page in packets| U

Figure 2: Opening an Online Shop: DNS, Routing, and Response

Internet Infrastructure in Nepal

Nepal’s geography presents unique challenges for internet connectivity, leading to a specific infrastructure landscape.

1. International Connectivity

As a landlocked country, Nepal accesses the global submarine cable network through two primary routes:

  • Southern Route: Data enters via India (mostly through Bhairahawa, Birgunj, and Biratnagar) connecting to submarine cables in the Indian Ocean.
  • Northern Route: A newer optical fiber link through the Himalayas into China (Rasuwagadhi border) provides a strategic alternative to the Indian route.

2. NIXP (Nepal Internet Exchange Point)

Nepal has its own local exchange point (NIXP) in Kathmandu. It allows local ISPs like Worldlink and Nepal Telecom to exchange local traffic (e.g., a Worldlink user sending an email to an NT user) without needing to use expensive international bandwidth.

3. The FTTH Boom

Over the last decade, Nepal has seen a massive shift from ADSL (copper) to FTTH (Fiber). This has enabled the growth of bandwidth-heavy services like YouTube, TikTok, and high-definition e-commerce platforms (Daraz).

4. Weak Points

  • Dependence on a few cross-border links: Most international traffic still passes through India, so a cut cable or a policy decision across the border can slow the whole country.
  • Geography: Landslides and floods damage fibre in the hills, and remote areas depend on mobile or satellite links.
  • Cost of international bandwidth: Traffic that leaves the country is expensive, which is why local hosting, caches, and NIXP matter.

Summary

The Internet is a layered system: physical networks, TCP/IP protocols, applications, and users. Tier-1 backbone providers carry traffic across continents; regional ISPs buy transit and connect customers through last-mile technologies such as fibre and mobile. Internet exchange points keep local traffic local. Data moves as packets: IP addresses and routes each packet, and TCP makes delivery reliable. DNS translates domain names into IP addresses. In Nepal, international traffic enters through India and, increasingly, China; NIXP keeps local traffic in the country; and fibre to the home has transformed access in cities.

Key Takeaways

  • The Internet has four layers: network technology, transport (TCP/IP), applications, and users.
  • Backbone providers, ISPs, IXPs, and last-mile access form the physical infrastructure.
  • Packet switching breaks data into packets that routers forward independently.
  • IP handles addressing and routing; TCP handles reliable, ordered delivery.
  • DNS turns names like daraz.com.np into IP addresses.
  • Local hosting, CDNs, and NIXP make e-commerce sites in Nepal faster and cheaper to run.

Discussion Questions

  1. Why is the “Last Mile” often considered the most expensive and slowest part of the internet infrastructure?
  2. How does Cloud Computing change the way businesses think about their own server infrastructure?
  3. Explain the importance of the China-Nepal fiber link for Nepal’s digital sovereignty.

Exam-Style Questions

Short answer

  1. What is an internet backbone?
  2. What is an Internet Exchange Point (IXP)? Why is NIXP important for Nepal?
  3. Define packet switching.
  4. Distinguish between IPv4 and IPv6.
  5. What is DNS?

Long answer

  1. Describe the layered architecture of the Internet and the role of each layer.
  2. Explain the TCP/IP protocol suite and how TCP and IP work together to deliver a web page.
  3. Describe Nepal’s internet infrastructure, including international connectivity, NIXP, and last-mile access, and discuss its weak points.