Comprehensive Study Notes on Computer Networks

Fundamentals of Computer Network

Unit-1

Definition of Computer Network

  • A computer network consists of two or more computing devices connected to share resources and stored information.

Basic Structure and Expansion of Computer Networks

  • Basic Network: A fundamental computer network, comprising merely two connected computers, can expand by adding more computers, thereby enhancing usability and resource sharing.

  • Visual Representation: Figure 1.1 illustrates a simple scenario where two or more computers communicate within a network.

Need for Computer Networks

  • Communication:

    • Enables collaboration among individuals and organizations using communication channels such as email, chat, and video conferencing.

  • Resource Sharing:

    • Facilitates sharing of printers, scanners, and files, enhancing work activities and reducing operational costs.

  • Collaboration:

    • Offers opportunities for joint efforts, sharing ideas, and promoting efficient teamwork.

  • E-commerce:

    • Supports online sales and secure payment processing, allowing businesses to engage in internet commerce.

  • Remote Access:

    • Provides information and support access globally, enabling users to work from various locations.

  • Education:

    • Supports distance learning, access to higher education resources, and collaboration between students and teachers.

  • Entertainment:

    • Facilitates online gaming, film and music streaming, and social networking applications.

Applications of Computer Networks

  • Business Applications:

    • Essential for effective communication, resource sharing, and remote access for employees.

  • Educational Applications:

    • Widely adopted in educational settings to enable access to resources and collaborative opportunities.

  • Healthcare Applications:

    • Utilized for storing and sharing patient details, improving personalized healthcare delivery.

  • Entertainment Applications:

    • Enables online gaming, music and film streaming, and social media interactions.

  • Banking and Finance Applications:

    • Extensively used for transactional processing, information sharing, and secure service access.

  • Military Applications:

    • Mostly closed networks ensuring safety of sensitive military communications.

  • Scientific Applications:

    • Supports collaboration among researchers and data sharing in scientific studies.

  • Transportation Applications:

    • Used for traffic management, vehicle tracking, and enhancing transport efficiency.

Advantages of Computer Networks

  • Improved communication and collaboration

  • Resource sharing that can reduce costs

  • Enhanced data quality management and security

  • Increased automation and remote access capabilities

  • Improved productivity and efficiency through resource sharing (printers, application services) and information sharing (file sharing)

Disadvantages of Computer Networks

  • Risks of data hacking and potential data leakage

  • Technical and operational issues may arise

  • Increased likelihood of exposure to viruses and malware

  • Potential decrease in privacy

Hardware & Software Components of a Computer Network

  • Key Components:

    • The hardware includes:

    • Internet

    • Router

    • Transmission Media

    • Server

    • Bridge

    • Hub

    • Printer

    • Repeater

    • Workstation

  • Computer Network Hardware Components consist of servers, clients, peers, transmission mediums, and connecting devices.

Details of Computer Network Hardware Components

  • Servers:

    • High-configuration computers managing network resources. Network Operating Systems (NOS) are installed on servers. Different types include file servers, database servers, and print servers.

  • Clients:

    • Computers that request and receive services from servers to utilize network resources.

  • Peers:

    • Computers that provide and receive services within a workgroup environment.

  • Transmission Media:

    • Channels for data transfer from one device to another, categorized into guided media (e.g., coaxial cables, fiber optic cables) and unguided media (e.g., microwaves, infrared waves).

  • Connecting Devices:

    • Middleware that binds network media, including Routers, Bridges, Hubs, Repeaters, Gateways, and Switches.

Uses of Computer Networks

For Companies

  1. Internal Communication

  2. Data Sharing and Collaboration

  3. Resource Sharing

  4. Access to External Resources

  5. Security and Data Protection

  6. Business Applications and Services (e.g., ERP)

  7. Cloud Services

  8. Scalability and Growth

For Social Issues

  1. Promoting Social Awareness and Advocacy:

    • Includes raising awareness and running campaigns or crowd-sourcing support.

  2. Improving Education and Awareness:

    • Supports online learning platforms and public service campaigns.

  3. Enabling Access to Essential Services:

    • Facilitates healthcare access.

  4. Connecting and Empowering Marginalized Communities

  5. Disaster Relief and Crisis Management

  6. Enhancing Political Participation and Civic Engagement

Examples of Networks

  1. The World Wide Web:

    • A directed network with nodes representing web pages and edges as hyperlinks.

  2. Power Line and Airline Networks

  3. Citation Networks:

    • Links scholarly papers through bibliographic references.

  4. Social Networks

  5. Economic Networks

Classification of Computer Networks

  • Networks can be classified based on different criteria including:

    • Geographical spread

    • Topology

    • Ownership

Types of Computer Networks by Geographical Spread

  1. LAN (Local Area Network):

    • Connects computers within a small area (buildings, offices).

    • Covers distances of 1-5 km and typically less costly.

    • Utilizes inexpensive hardware like hubs, network adapters, and Ethernet cables.

    • Transfers data at high speed, supporting 20-50 devices with higher security, commonly using star topology.

  2. MAN (Metropolitan Area Network):

    • Connects different LANs covering larger areas.

    • Distance can be up to 50 km, supporting about 1000 devices.

    • Uses various topologies (mesh, star) and protocols (RS-232, Frame Relay, ATM, ISDN, ADSL).

  3. WAN (Wide Area Network):

    • Extends across large geographical areas like countries or continents.

    • Allows millions of devices to be connected, not limited to a location.

    • Utilizes telephone lines, fiber optic cables, or satellite links, with the Internet being the largest WAN.

  4. PAN (Personal Area Network):

    • Arranged within the individual's personal range (about 10 meters).

    • Connects personal devices, supporting up to 10 devices within a 30-foot range, typically using star topology.

  5. CAN (Campus Area Network):

    • Connects multiple buildings in limited geographical areas like a university.

    • Larger than LAN but smaller than MAN, often using various topologies (star, bus, ring, mesh).

Wireless Networks

  • Defined as networks using wireless data connections between nodes.

  • Communication typically occurs via radio waves, allowing devices to connect while roaming within network coverage.

Types of Network Component Roles

  1. Peer to Peer (P2P):

    • No dedicated servers; workstations connected for device and information sharing.

    • Each computer acts as both client and server, suitable for small networks (home, small businesses).

  2. Client/Server Network:

    • Model where clients access resources from a central server.

    • Server manages resources and operates security and network management functions.

Advantages and Disadvantages of Peer-To-Peer Network

Advantages

  • Cost-effective due to lack of dedicated server

  • Reliability; if one computer fails, others continue functioning

  • Easy setup and management

Disadvantages

  • No centralized management for data backup

  • Security concerns; each device manages itself

Advantages and Disadvantages of Client/Server Architecture

Advantages

  • Centralized data management simplifies backups

  • Dedicated servers enhance performance

  • Greater security under a single server management

  • Improved speed in resource sharing

Disadvantages

  • High costs associated with server maintenance and operating systems

  • Requirement for dedicated network administrators

Comparison Between Client-Server and Peer-to-Peer Network

  • Basic Service Focus:

    • Client-Server: Specific server and clients with defined roles.

    • Peer-to-Peer: Nodes function interchangeably as clients and servers.

  • Data Management:

    • Client-Server: Data centralized, leading to potential bottlenecks.

    • Peer-to-Peer: Data distributed across peers, reducing bottleneck risks.

  • Usability and Scale:

    • Client-Server: Generally more stable and scalable, yet more expensive.

    • Peer-to-Peer: Less costly, but performance may decline as more peers connect.

Comparison of LAN, MAN, and WAN

LAN (Local Area Network)

  • Coverage: Limited to a small geographical area.

  • Use Cases: Colleges, schools, hospitals

  • Expense: Easy to manage with short propagation delay, high speed, and more fault tolerance.

MAN (Metropolitan Area Network)

  • Coverage: Larger than LAN, spans cities and towns.

  • Use Cases: Multiple computers interact simultaneously.

  • Expense: More difficult to manage with moderate propagation delay.

WAN (Wide Area Network)

  • Coverage: Encompasses countries/continents, connecting a vast number of computers simultaneously.

  • Expense: Difficult to manage with longer propagation delay and lower speeds, less fault tolerance.