chapter 1

Data Communications

The process of sharing information (data) between two devices over a physical connection.

What are the four key characteristics of data communications?

Delivery, Accuracy, Timeliness, Jitter.

What is Delivery, as a characteristic of data communications?

Data must reach the correct destination (only the intended device/user).

What is Accuracy, as a characteristic of data communications?

Data must be sent without errors; any change during transmission can make it unusable.

What is Timeliness, as a characteristic of data communications?

Data needs to arrive on time; delays can render it useless.

What is Jitter, as a characteristic of data communications?

Variation in packet arrival times that can cause uneven quality.

Main Components of a Data Communications System

Message, Sender, Receiver, Transmission Medium, Protocol.

What is Message, as a component of a Data Communication System?

The actual data (text, numbers, images, audio, video) being communicated.

What is Sender, as a component of a Data Communication System?

The device that sends the data (e.g., computer, phone).

What is Reciever, as a component of a Data Communication System?

The device that receives the data.

What is Transmission Medium, as a component of a Data Communication System?

The physical path (like wires or radio waves) that data travels on.

What is Protocol, as a component of a Data Communication System?

A set of rules that allows the sender and receiver to understand each other.

What are the data flow types?

Simplex, Half-Duplex, Full-Duplex.

Explain Simplex

One-way communication (e.g., keyboard to monitor).

Explain Half-Duplex

Two-way communication but not at the same time (e.g., walkie-talkies).

Explain Full-Duplex

Simultaneous two-way communication (e.g., telephone calls).

What is a network?

A connection that allows devices (like computers, phones, routers) to communicate.

Key criteria for a network

Performance, Reliability, Security.

Performance (in networking context)

Measured by how fast data travels and how quickly a device responds.

Reliability (in networking context)

How often the network fails and how quickly it recovers.

What is a point-to-point connection?

A dedicated link between two devices.

What distinguishes local area network (LAN) from wide area network (WAN)?

LAN covers a small area while WAN covers larger areas, like cities or countries.

What is an internetwork?

When two or more networks are connected.

TCP/IP Protocol Suite

A collection of protocols used on the Internet, organized into layers.

What are the layers of the TCP/IP model?

Application, Transport, Network, Data-Link, Physical.

What role does the Physical Layer have in TCP/IP?

Carries individual bits across the physical medium.

OSI Model

A framework defined by ISO to help design and understand network systems.

What are the layers in the OSI Model?

Physical, Data-Link, Network, Transport, Session, Presentation, Application.

Key difference between OSI and TCP/IP

TCP/IP has 5 layers as it combines or omits some of the OSI layers.

What role does the Application Layer have in TCP/IP?

responsible for providing network services directly to the end user and supports application-level protocols such as HTTP, FTP, and SMTP.

What role does the Transport Layer have in TCP/IP?

is responsible for ensuring that data is transmitted between hosts reliably and accurately, managing error detection and correction, and providing flow control.

What role does the Data-Link Layer have in TCP/IP?

responsible for node-to-node data transfer and error detection in the physical layer, ensuring reliable communication between directly connected devices.

What role does the Network Layer have in TCP/IP?

responsible for routing data packets between devices across different networks, managing logical addressing through IP addresses, and determining the optimal path for data transmission.