Data Communications: Network Topologies and Categories, Lecture notes of Data Communication Systems and Computer Networks

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Introduction

Week 01

Introduction

• Network Topologies and Categories
• The Internet, Protocols and Standards

Data Communications

• Data: the information presented in whatever form is agreed

upon by the parties creating and using the data.

• Data Representation (text, numbers, images, audio, videos).
• Communications: the exchange of data between two devices

via some form of transmission medium.

• Telecommunication: communication at a distance, e.g.

telephony, television and telegraphy.

Data Communication System

• Communication devices must be part of a system, know

as data communication systems.

• Communication systems are made up of a combination:

1. Hardware (physical equipment)

2. Software (programs)

Characteristics of Data Communication Systems

• Fundamental characteristics required in data communication system for an effective communication: 1. Delivery: system must deliver data to the correct destination. 2. Accuracy: system must deliver data without alteration. 3. Timeliness: system must deliver data in a timely manner. 4. Jitter: system should have a proper variation in packets inter- arrival time to their destination.

*Jitter: usually referred for the uneven delay in delivery of packets.

Characteristics of Data

Communication Systems (Cont.)

Hi, how are you?

01010001

Hi, how are you?

Computer User

you?

how are

Hi,

you?

how are

Hi,

01010001

Networks

Networks

• Network: is a set of devices (often

referred to as nodes ) connected by

communication links.

• Internetwork (Internet): the inter-

connection of networks.

Networks (Cont.)

• Link: a communication

channel that transfers data from one device to another.

• A link can be a cable, air,

optical fiber, or any medium which can transport a signal carrying information.

Physical Structures &

Network Topologies

Physical Structures (Cont.)

Physical Structures (Cont.)

• Network Topology: the way the network is physically laid out.
• Network Topology: the geometric representation of the relationship of all links and linking devices to one another.
• Four basic topologies:

Star Topology

• Every device has dedicated point-to-point link to a central controller.
• Centrally controlled setup implies that devices are not directly connected to each other.
• One link and one I/O is required at each device.
• Advantages: less expensive and less resources required than mesh, easy fault isolation.
• Disadvantages: controller loss.
• Applications: Local Area Networks (LANs).

Bus Topology

• Bus topology is a multipoint connection example.
• Nodes connected to bus cable by drop lines and taps.
• There are limitations on number of taps and distance between taps.
• Advantages: easy to install, less resources than star.
• Disadvantages: difficult reconnection, addition & fault isolation. Any break stops all transmission due to signal reflection.
• Applications: traditional LANs, i.e. less popular nowadays.