Network Topologies Quiz

Data Communications

• Data communications is the exchange of data between two or more connected devices.

Introduction to Data Communications

• Data can include text, images, audio, video, and multimedia files.
• Communication is the act of sending or receiving data.
• Data communication refers to the exchange of data between two or more networked devices.
• These devices must be able to send and receive data via a communication medium.

Examples of Devices

• Personal computers
• Mobile phones
• Laptops

Simple Network

• A simple network comprises four types of devices: computer, printer, server, and switch.
• These devices are interconnected through a medium to carry information from one end to the other.

Forces Driving Communication

• The continual growth in data traffic
• Development of new services
• Advancements in technology

Intended Learning Outcomes

• Define terms related to data, data communications, and data communication networks.
• Describe the evolution of data communications.
• Define data communications networks architecture.
• Describe data communications protocols.
• Explain the basic concepts of connection-oriented and connectionless protocols.
• Describe syntax and semantics and how they relate to data communications.
• Define data communication standards and explain their necessity.

Data vs Information

• Data: Raw, unorganized facts and figures
• Information: Data that is organized, structured, and processed to be meaningful.

Data Communications Model

• Source: Generates data to be transmitted.
• Transmitter: Converts data into transmittable signals.
• Transmission system: Carries data from the source to the destination.
• Receiver: Converts the received signal into data.
• Destination: Takes incoming data.

Data Communications Do

• Enables information systems to deliver information.
• Improves the flexibility of data collections and transmission.
• Forms the basis for virtual organizations.
• Provides e-collaboration.

Basic Concepts of Data Communication

• Bandwidth: Amount of data transferrable in a specific time period.
• Attenuation: Loss of power in a signal as it travels.
• Broadband: Simultaneous transmission of multiple data pieces to increase rate.
• Narrowband: Limited transmission rate (e.g., voice-grade).
• Protocols: Rules that govern data communication, including error detection, message length, and transmission speed.

5 Components of Data Communication

• Sender
• Protocol
• Message
• Medium
• Receiver

Data Representation

• Text: ASCII (7-bit) and Extended ASCII (8-bit), Unicode (32-bit).
• Numbers: Binary numbers.
• Images: Matrix of pixels.
• Audio: Continuous analog signal.
• Video: Can be analog or digital.

Data Flow

• Simplex: One-way communication.
• Half-duplex: Two-way communication, but not simultaneous.
• Full-duplex: Two-way communication, simultaneous.

Networks

• Growth of computers and their power created the need for interconnection.
• Data, voice, and video technologies are rapidly integrating.
• Two broad categories of networks: LANs and WANs

Network Components

• Network: A collection of interconnected devices.
• Node: A device capable of sending and receiving data.
• Link: The path between nodes over which data travels.

Communication Media

• Selection depends on internal or long-distance use.
• Technology changes the mix of media (e.g., fiber optic, wireless).
• Transmission costs are still high, necessitating efficiency improvements.
• Types of media include: twisted pair wire, coaxial cable, fiber optic cable, radio, infrared, satellites.

Physical Structure

• Type of connection: point-to-point (single transmitter/receiver); multipoint (multiple recipients of a single transmission).
• Physical topology: Connection of devices (e.g., bus, star, ring, mesh, tree, hybrid)
• Transmission type: unicast, multicast, broadcast.

Types of Connection

• Point-to-Point Protocol (PPP): Defines the communication between two devices.
• Multipoint Connection: A connection in which multiple devices share a single communications link.

Types of Network Topologies

• Star Topology
• Ring Topology
• Bus Topology
• Tree Topology
• Hybrid Topology
• Mesh Topology

Circuit Switching

• A dedicated communication path is established for the duration of the conversation.
• The path comprises a sequence of physical links, creating a dedicated logical channel.
• Resources are dedicated throughout the call duration.
• Example: Telephone network.

Packet Switching

• Data is divided into small chunks called 'packets'.
• Packets are sent along different paths, potentially out of sequence.
• The network shares resources between packets.

Why Resource Sharing

• Packet switching is more efficient compared to circuit switching when users are 'bursty', meaning they send and receive data in bursts interspersed with periods of inactivity.

Protocols

• Rules that govern data communication between network elements.
• Defines message formats, timing, and actions.

Standard Bodies

• Organizations that define and standardize data communications.
• Examples include: ISO, ITU, ANSI, IEEE, Telcordia, ETSI, IAB, IETF, IRTF, OMG, WWW consortium.

The Internet

• Evolved from ARPANET.
• First operational packet network.

Networking Today

• Growth and interconnection of computers.

The Changing Environment

• Devices accessing data & content via various networks (BYOD).

Network Trends; Online Collaboration; Cloud Computing

• Cloud computing benefits (organizational flexibility, agility, reduced cost).

OSI Layer - Physical Layer

• Controls how data is placed on physical media (copper wires, fiber optics, wireless).
• Encodes binary digits into signals.
• Transmits and receives signals across the media.

OSI Layer - Data Link Layer

• Provides error-free communication across physical links.
• Frames data into blocks to be transmitted.
• Handles physical addressing and error detection.

OSI Layer - Network Layer

• Enables routing data between different networks/subnetworks.
• Includes routers and their software for data routing.

OSI Layer - Transport Layer

• Controls the end-to-end integrity of data transmission.
• Handles message routing, segmentation, error recovery.
• Provides connection-oriented and connectionless services to upper-layer protocols.
• The transport layer is the highest layer in the OSI hierarchy in terms of communications, and may provide data tracking, connection flow control, sequencing of data, error checking, and application addressing and identification.

OSI Layer - Session Layer

• Responsible for network availability (data storage and processor capacity).
• Provides logical connection entities for applications.
• Includes network log-on/log-off and user authentication procedures.

OSI Layer - Presentation Layer

• Ensures data independence for application processes.
• Addresses code and syntax conversion for data presentation in a standard communication format.
• Supports encryption, compression, and virtual terminals.

OSI Layer - Application Layer

• Highest layer in the hierarchy, akin to the general manager of the network.
• Provides access to the OSI environment.
• Distributes information services, controlling interactions between applications and users.

Transmission Modes (Two-wire and Four-wire Circuits)

• Two-wire circuits:
  • Used for short distances.
  • Generally analog.
  • Lower quality/performance due to analog transmission.
• Four-wire circuits:
  • Facilitate multiple simultaneous communications in full duplex mode.
  • Improve error performance due to digital transmission.

Transmission Media

• Guided Media:
  • Twisted-pair cable
  • Coaxial cable
  • Fiber-optic cable
• Unguided Media:
  • Radio waves
  • Microwaves
  • Infrared