Data Communication Fundamentals

Data Communications Introduction

• Telecommunication means communication at a distance
• Data refers to information agreed upon by parties using it
• Data communications is the exchange of data between two devices via a transmission medium like a wire cable

Fundamental Characteristics

• The effectiveness of a data communication system depends on these four characteristics:
  • Delivery: The system must deliver data to the correct destination
  • Accuracy: It should deliver data accurately
  • Timeliness: Data should be delivered in a timely manner
  • Jitter: Jitter refers to the variation in delay

Components of Data Communication

• A data communication system consists of five key components:
  • Message: The information to be communicated
  • Sender: The device that sends the data message
  • Receiver: The device that receives the message
  • Medium: The physical path through which the message travels
  • Protocol: A set of rules governing data communication

Direction of Data Flow

• Simplex: Communication occurs in one direction only
• Half-Duplex: Both stations can transmit, but only one at a time
• Full-Duplex: Both stations can transmit simultaneously

Network Key Issues

• Network criteria includes performance, reliability and security
• Performance: measured by throughput and delay
• Reliability: Data transmitted exactly matches data received, measured by the frequency of failure and recovery time
• Security: Protecting data from unauthorized access

Terminology

• Throughput or Bandwidth: The number of bits a channel can transfer per second
• Latency or Delay: The time it takes for information to travel from sender to receiver

Network Topologies Introduction

• Topology defines how hosts are connected in a network
• A goal of any topology is high throughput (bandwidth) and low latency

Bandwidth and Latency Deep Dive

• Bandwidth in Telecommunications: The range of radio frequencies used in radio or telecommunications transmission and reception

• Bandwidth in Computing: Communication capacity of a channel, like an internet connection, measured in bits per second

• Bandwidth as Data Transmission Rate: The maximum amount of information (bits/second) that can be transmitted along a channel

• Latency: A synonym for delay, is the measure of time it takes for transmission from one point to another

Topology Categories

• Mesh Topology
• Star Topology
• Bus Topology
• Ring Topology

Mostly Used Network Topologies

• Mesh: Each device is connected to every other device for redundancy and high bandwidth
• Bus: All devices connect to a central cable, simple but can have collisions
• Ring: Each device connects to two neighbors, data travels in a circle
• Star: Each device connects to a central hub or switch, easy to manage

Hybrid Topology

• Hybrid topology is a combination of different topologies like: a Star backbone with three bus networks

Internet Hierarchy

• The Internet has a hierarchical organization
  • From national ISPs down to regional ISPs and individual users

Layering and Protocol Stacks Introduction

• Layering & Protocol Stacks facilitate efficient data communication.

Protocols Detailed

• Protocols define the format, order, and actions taken during message transmission and receipt among network entities

Standards Importance

• Standards are essential for creating a competitive equipment market and ensuring interoperability of data and telecommunication technology

Layered Tasks

• Layered tasks mirrors the everyday life of physical mail delivery.

Why Layered Communication

• Layered communication reduces complexity by dividing tasks
• Functionality can be changed without affecting upper layers
• Each Layer has its own task and protocol

Reference Models

• OSI reference model
• TCP/IP

OSI Reference Model Explained

• OSI stands for Open Systems Interconnection model
• The model has 7 layers

OSI Design Principles

• Design involves these abstract principles:
  • Create a layer when a different level of abstraction is needed
  • Ensures each layer performs a well-defined function
  • Standardized protocols selected
  • The number of layers is large enough to avoid complexity

OSI Model Diagram

• The seven layers of the OSI model from top to bottom:
• Application
• Presentation
• Session
• Transport
• Network
• Data Link
• Physical

TCP/IP Model Explained

• The TCP/IP model is a fundamental framework for computer networking
• TCP/IP Stands for Transmission Control Protocol/Internet Protocol and include core protocols of the Internet.
• The TCP/IP model structure consists of this layered model:
  • Application Layer
  • Transport Layer (TCP/UDP)
  • Network/Internet Layer (IP)
  • Network Access Layer

TCP/IP Model vs OSI

• Comparison:
  • The OSI model has 7 layers
  • The TCP/IP model compresses this into 4 layers