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Chapter 1- Overview of Network �and Data Communication

  • Fundamentals of DCN & CN
    • To communicate & provide connections
  • Data communication
  • Computer Networking
  • Protocols and Standards
  • Types of networks
  • Network topology
  • Protocol hierarchies
  • Design issues for the layers
  • Interfaces and services

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Computer Networks

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Communication�?

Computer Networks

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Computer Networks

Electronic way (Analog/Digital)

Communication�?

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Data Communication System Components

Computer Networks

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Data Communication

  • Exchange of data (transfer) between two devices via transmission medium with some protocol.
  • Transmission mode:
          • Simplex, Half duplex, Full Duplex
          • Serial transmission & Parallel Transmission

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Computer Networks

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Simplex

Computer Networks

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Computer Networks

Image reference:

https://afteracademy.com/blog/what-are-the-data-transmission-modes-in-a-network

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Computer Networks

Image reference:

https://afteracademy.com/blog/what-are-the-data-transmission-modes-in-a-network

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Computer Networks

Image reference:

https://afteracademy.com/blog/what-are-the-data-transmission-modes-in-a-network

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Criteria for effective and efficient communication

Computer Networks

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Protocols and Standards

Computer Networks

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Computer Networking

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Computer Networks

Define Network:

A Network is a set of devices (nodes) connected by media links.

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A node can be a computer, printer, or any other device capable of sending and / or receiving data generated by other nodes on the network.

  • Network
  • Networking
  • Computer Networking

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Types of Network

Computer Networks

  • LAN, MAN, WAN
  • Intranet & internet (internetwork)
  • Internet – Worldwide network.

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Categories of Network

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Local Area Network

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Local Area Network

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Metropolitan Area Network

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Figure 2-18

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Wide Area Network

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Figure 2-19

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Internetwork

(Internet)

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Figure 2-4

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Categories of Topology

Network Topology

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Figure 2-5

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Mesh Topology

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Mesh

  • Dedicated point to point links.
  • If n nodes then n(n-1) physical links. (simplex)

& n(n-1)/2 for duplex link

  • Robust topology – about failure of link
  • Advantage
    • privacy & security
  • Disadvantages.
    • Nr. of I/O port & cables require
    • Installation & reconnection are difficult
    • Expensive system

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Figure 2-6

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Star Topology

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Star

  • Central controller device

Hub / Switch

  • Advantage
    • Less expensive than mesh
    • Easy installation & reconfiguration
    • System is robustness.
  • Disadvantages.
    • If Central device goes down then whole system down
    • More cable in star than (ring, bus)

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Figure 2-7

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Tree Topology

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Figure 2-8

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Bus Topology

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Bus

  • Point to point, multipoint connection
  • Cable – Backbone (coaxial)

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  • Advantage
    • Bus uses less cable than ( mesh, star )
    • Easy installation
  • Disadvantages.
    • Difficult to reconnect & fault isolation
    • Signal reflection at Tap can make poor quality
    • Limiting the Nr. of devices

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Figure 2-9

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Ring Topology

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Ring

  • Signal in ring (one direction)
  • Every device work as a Repeater

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  • Advantage
    • Easy installation & configuration.
    • If device does not receive signal then it issue Alarm
  • Disadvantages.
    • Unidirectional Traffic
    • Break line can disable the network

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Protocol Hierarchies

  • Protocol is an agreement between communicating parties on how communication is to proceed
  • Layers (Levels) provide service to above layers

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  • Layer translator…

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Design Issues for the Layers

  • Identify sender and receiver (addressing)
  • rule for data transfer- direction, logical channel conn
  • Reliability- operate correctly
    • Error detection (retransmission)
    • error correction
    • Routing
  • Protocol layering (hiding implementation details)
    • addressing or naming (high level)
    • size of a message
    • Scalable- when the network gets large

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Design Issues for the Layers

  • Resource allocation.
    • capacity of transmission lines (Flow Control)
    • Congestion (overloading of the network)
    • networks must provide service to applications that want real-time delivery (quality of service)
  • secure the network
    • eavesdropping on communications by threat (Confidentiality)
    • Authentication (prevent unauthorized access)
    • Integrity (prevent surreptitious changes to messages)

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Connection-Oriented Versus Connectionless Service

  • Reliable, virtual circuit, sequence of pkt
  • Unreliable datagram
  • Request-reply (e.g. location wise map)

Service primitives

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OSI Reference Model

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ISO has developed a standard. ISO stands for International organization of Standardization.

This is called a model for Open System Interconnection (OSI) and is commonly known as OSI model.

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Network Architecture

  • Peer to Peer
  • Client – Server

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Point-to-Point Line Configuration

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Network Architecture

  • Client – Server

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Compare: peer to peer Vs client-server

Setup n/w, Cost, OS, Manage, Security,

Systems: PC/Server, Admin skill, etc..

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Example Networks.

-Internet: - internetworking

not planned by any one

not controlled by any one

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ARPANET: Advance Research Project Agency

1950-1960

command & control network

military application

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NSFNET: National Science Foundation Network

1970

Back bone connection

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ARPANET

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Example Networks. Cont..

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Ethernet LAN

-Co-axial cable- up to 2.5 km

repeater at every 500 meters

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-max. 256 machines connected via Transceiver

-multi drop cable used

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- speed 2.94 Mbps

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Ethernet card, cable, connector, & network

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Example Networks. Cont..

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Example Networks using Repeater. Cont..

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Example Networks. Cont..

Ethernet card, cable, connector, & network

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Example Networks. Cont..

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Addresses at layer

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End of Part-1

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Wired Network (Twisted pair, RJ-45)

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End of Part-1

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Thanks.

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