Introduction

Chapter 1: Introduction

Goals of the Chapter

  • Provide an overview and introduction to fundamental concepts of computer networking and the Internet.

  • Develop a foundational understanding of terminology and concepts that will be elaborated in later chapters.

  • Aim to provide a "big picture" perspective of computer networks.

Overview/Roadmap

  • What is the Internet?

  • What is a protocol?

  • Network Edge: Hosts, Access Network, Physical Media

  • Network Core: Packet Switching, Circuit Switching, Internet Structure

  • Performance Measures: Loss, Delay, Throughput

  • Protocol Layers and Service Models

  • Security Considerations

  • History of the Internet

The Internet: A Nuts and Bolts View

Basic Components of the Internet

  • Network structure consists of:

    • Mobile networks

    • Home networks

    • Enterprise networks

    • Local and Regional ISPs

    • National or Global ISPs

    • Data center networks

    • Content provider networks

Key Components in Data Transmission

  • Packet Switches: Forward packets which are data chunks.

    • Examples include routers and switches.

  • Communication Links:

    • Types include fiber, copper, radio, and satellite links.

    • Transmission Rate: Defined as bandwidth.

  • Hosts: End systems that run applications at the Internet's edge.

Examples of Fun Internet-Connected Devices

  • Web-enabled toaster, weather forecaster, IP security camera.

  • Amazon Echo, smart refrigerators, and various gaming devices.

Protocols in Networking

Understanding Protocols

  • Definition: Set of rules that govern communication between networked devices.

    • Examples include HTTP, streaming protocols, TCP/IP, and Wi-Fi.

  • Protocols control message formats and transmission orders.

Network Structure

Internet as a "Network of Networks"

  • The Internet consists of interconnected ISPs and serves as a complex web of networks.

  • Internet Standards: Set by IETF (Internet Engineering Task Force) via RFC (Request for Comments).

Infrastructure Services3

  • Provides services related to:

    • Web browsing

    • Multimedia streaming

    • Email communication

    • E-commerce

    • Social media interactions

Network Edge and Core

Network Edge Components

  • Hosts: Clients and servers; servers often located in data centers.

  • Access Networks: Wired and wireless communication links.

Network Core Overview

  • Comprised of interconnected routers that manage packet forwarding and network routing.

Access Networks

Connecting End Systems to Edge Routers

  • Types of access networks:

    • Residential access,

    • Institutional access (schools or businesses),

    • Mobile access (e.g., Wi-Fi, 4G/5G).

Cable-based Access Networks

  • Hybrid Fiber Coax (HFC): Combining fiber and coaxial to connect homes to ISPs.

  • DSL (Digital Subscriber Line): Uses existing phone lines for networking.

Transmission and Media Types

Physical Media Types

  • Twisted Pair (TP): Commonly used in Ethernet networks.

  • Coaxial Cable: Used for broadband networks, typically bidirectional.

  • Fiber Optic Cable: High-speed transmission with low error rates.

  • Wireless Media: Variants include Wi-Fi, Bluetooth, and satellite communications.

Packet Switching vs. Circuit Switching

Packet Switching Concepts

  • Store-and-forward Technique: Requires the entire packet to arrive before forwarding.

  • Queueing and Delay: Examines how packets queue up when transmission exceeds capacity.

Circuit Switching Overview

  • Allocates resources for calls between device pairs, ensuring dedicated performance.

Comparing Packet and Circuit Switching

  • Packet switching allows for resource sharing and handles bursty data but may experience congestion, unlike circuit switching which may have dedicated links but can waste resources when idle.

Internet Structure and Design

Interconnection of ISPs

  • Access ISPs interconnect to allow communication across networks.

  • Direct connections increase complexity, thus global transit ISPs facilitate this interconnectivity efficiently.

Regional Networks and ISPs

  • Competitors are likely to emerge to provide connectivity options, creating a diverse network landscape.

Security in Networks

Challenges Faced

  • Denial of Service Attacks: These overwhelm networks with bogus requests, making them unavailable to legitimate users.

  • Packet Interception and Identity Spoofing: Vulnerabilities exploited to gain sensitive data or impersonate valid users.

Lines of Defense

  • Authentication, encryption, integrity checks, and firewalls serve as barriers against malicious attacks.

Layering in Protocols

Purpose of Layering

  • Organizes network protocols into layers to ease complexity and troubleshoot effectively.

  • Each layer serves as a module that relies on the services of the layer below.

Internet Protocol Layers

  • Application Layer: Supports network applications (e.g., HTTP, DNS).

  • Transport Layer: Responsible for process-to-process data transfers (e.g., TCP, UDP).

  • Network Layer: Handles routing of datagrams.

  • Link Layer: Manages data transfers between neighboring elements.

Encapsulation Process

  • Each layer encapsulates data from the layer above, allowing for structured data transfer throughout the network.

Internet History

Key Milestones

  • 1960s: Theories of packet-switching developed; ARPAnet introduced.

  • 1980s: TCP/IP adoption and the establishment of DNS.

  • 1990s: The commercialization of the internet and creation of the World Wide Web.

  • 2000s to Present: Increase in wireless access, cloud computing, and overwhelming device connectivity.

Summary

  • The chapter provided an extensive overview of computer networking including concepts of the Internet, protocols, access networks, physical media, security, and historical milestones, setting a fundamental context for further in-depth study.