This document provides an overview of key concepts in data communication including: 1. The five components of a data communication system are the sender, receiver, message, transmission medium, and protocol. 2. Data flow can be simplex, half-duplex, or full-duplex depending on whether transmission is unidirectional or bidirectional. 3. Signals can be analog or digital, with digital signals taking on discrete values like 0 and 1. 4. Common networking devices include modems, hubs, switches, and routers which facilitate data transmission and routing. 5. Network addressing identifies nodes and is implemented through physical MAC addresses and logical IP addresses which are organized into classes.

1. Assignment on
Data flow, Signals, Networking addressing, Devices
Course Title : Data Communication
Course Code : CSE-313
Submitted To Submitted By
Pranab Bandhu Nath Al-hasib sarker
Lecturer ID: 1834902133
City University Batch:49(B)
B.Sc. in CSE

2. Data Communications
Data communication is defined as exchanges of data between two devices via some form of transmission media such as cable,
wire or it can be air or vacuum also. There are mainly five components of a data communication system. They are:
1. Sender: Sender or source transform message to destination.
2. Receiver: Receiver or destination receives message from source.
3. Message: It refers to data or piece of information which is to be communicated
4. Transmission medium: It is physical path by which data or message travels from sender to receiver. Transmission medium
could be with wires or without wires. For example twisted pair cable, fiber optic cable, radio waves, microwaves, etc.
5. Protocol: The protocol is a set of rules that govern data communication.

3. Data Flow
Communication between any two devices can be simplex, half-duplex, or full-duplex.
 Simplex: The communication is unidirectional. Only one of the two devices on a link can transmit; the other can only
receive.
 Half-duplex: Only one of the two devices on a link can transmit; the other can only receive.
 Full-duplex: In full-duplex mode both devices can transmit and receive.

4. Signals
There are two types of signals in data transfer:
 Analog signal: Analog signal are continuous and passes through or includes an infinite number of continuous values along
its path.
 Digital signal: Digital signal can have only a limited number of defined values. Each value can be any number, it is as
simple as 0 and 1.

5. Networking Devices
Mainly four devices are used in networking:
• Modem: Modem is a device that enables a computer to send or receive data over telephone or cable lines. The main
function of the modem is to convert digital signal into analog and vice versa.
• Hub: A common connection point for devices in a network. It contains multiple ports.
• Switch: It is a small hardware device that joins multiple computers together within one local area network.
• Router: It is a device that forwards data packets between computer networks, creating an overlay internetwork.

6. Network addressing or Data addressing
A network address is an identifier for a node or host on a telecommunications network. Network addresses are designed to be
unique identifiers across the network, although some networks allow for local, private addresses, or locally administered
addresses that may not be unique. Network addressing are two types:
Physical: MAC address is called physical address, which is 48 bit.
Logical: IP address is called logical address, which is 32 bit. The range of IP address is 0-255. Range are classified in five
classes.
 Class a: 1-126
 Class b: 128-191
 Class c: 192-223
 Class d: 224-239
 Class e: 240-255
127 is called loop back address.