COMPUTER NETWORKS & SECURITY
CONTENTS:
1. Introduction to Computer Networks
2. Components of Computer Networks
3. Computer Network Architecture:
4. Uses of Computer Networks
5. Network Hardware
6. Reference Models
7. Design Issues for The Layers
8. Connection-oriented Vs Connectionless Service:
9. Service Primitives
10. Reference Models
11. Design Issues of Datalink Layer
12. Error Detection and Correction
13. Sliding Window Protocol
1|Page
, Introduction to Computer Networks
Computer Network: A collection of autonomous computers interconnected by asingle
technology.
• Two computers are said to be interconnected if they are able to exchange
information.
• The aim of the computer network is the sharing of information andresources
among various devices.
• In the case of computer network technology, there are several types ofnetworks
that vary from simple to complex level.
Components of Computer networks:
A computer network comprises the following components:
➢ A minimum of at least 2 computers.
➢ Cables that connect the computers to each other, although wireless
communication is becoming more common.
➢ A network interface device on each computer (this is called a network
interface card or NIC).
➢ A switch used to switch the data from one point to another. Hubs are
outdated and are little used for new installations.
➢ A router that connects two or more networks or subnetworks.
➢ A modem that is used especially to transmit and receive informationbetween
computers via landlines
2|Page
,NIC (National interface card):
NIC is a device that helps the computer to communicate with another device. The
network interface card contains the hardware addresses. The data-link layer
protocol use this address to identify the system on the network so that it
transfers the data to the correct destination.
There are two types of NIC:
➢ Wireless NIC: All the modern laptops use the wireless NIC. In Wireless
NIC, a connection is made using the antenna that employs the radio wave
technology.
➢ Wired NIC: Cables use the wired NIC to transfer the data over the
medium.
3|Page
, Hub:
➢ Hub is a central device that splits the network connection into multiple
devices.
➢ When computer requests for information from a computer, it sends the
request to the Hub.
➢ Hub distributes this request to all the interconnected computers.
Switch:
➢ Switch is a networking device that groups all the devices over the network
to transfer the data to another device.
➢ A switch is better than Hub as it does not broadcast the message over the
network, i.e., it sends the message to the device for which it belongs to.
➢ Therefore, we can say that switch sends the message directly from source
to the destination.
Cables and connectors:
Cable is a transmission media that transmits the communication signals.
4|Page
CONTENTS:
1. Introduction to Computer Networks
2. Components of Computer Networks
3. Computer Network Architecture:
4. Uses of Computer Networks
5. Network Hardware
6. Reference Models
7. Design Issues for The Layers
8. Connection-oriented Vs Connectionless Service:
9. Service Primitives
10. Reference Models
11. Design Issues of Datalink Layer
12. Error Detection and Correction
13. Sliding Window Protocol
1|Page
, Introduction to Computer Networks
Computer Network: A collection of autonomous computers interconnected by asingle
technology.
• Two computers are said to be interconnected if they are able to exchange
information.
• The aim of the computer network is the sharing of information andresources
among various devices.
• In the case of computer network technology, there are several types ofnetworks
that vary from simple to complex level.
Components of Computer networks:
A computer network comprises the following components:
➢ A minimum of at least 2 computers.
➢ Cables that connect the computers to each other, although wireless
communication is becoming more common.
➢ A network interface device on each computer (this is called a network
interface card or NIC).
➢ A switch used to switch the data from one point to another. Hubs are
outdated and are little used for new installations.
➢ A router that connects two or more networks or subnetworks.
➢ A modem that is used especially to transmit and receive informationbetween
computers via landlines
2|Page
,NIC (National interface card):
NIC is a device that helps the computer to communicate with another device. The
network interface card contains the hardware addresses. The data-link layer
protocol use this address to identify the system on the network so that it
transfers the data to the correct destination.
There are two types of NIC:
➢ Wireless NIC: All the modern laptops use the wireless NIC. In Wireless
NIC, a connection is made using the antenna that employs the radio wave
technology.
➢ Wired NIC: Cables use the wired NIC to transfer the data over the
medium.
3|Page
, Hub:
➢ Hub is a central device that splits the network connection into multiple
devices.
➢ When computer requests for information from a computer, it sends the
request to the Hub.
➢ Hub distributes this request to all the interconnected computers.
Switch:
➢ Switch is a networking device that groups all the devices over the network
to transfer the data to another device.
➢ A switch is better than Hub as it does not broadcast the message over the
network, i.e., it sends the message to the device for which it belongs to.
➢ Therefore, we can say that switch sends the message directly from source
to the destination.
Cables and connectors:
Cable is a transmission media that transmits the communication signals.
4|Page
