Introduction to Computer Networks

Introduction to Computer Networks

Definition of Computer Network

• A group of computers and devices connected together via communication devices and transmission media to share resources.
• Computers can be geographically located anywhere.

Advantages of Networks

• Sharing information between devices
• Transfer data from one computer to another
• Share peripheral devices such as printers
• Share storage devices to store data for backup
• Use programs to communicate with other users
• Access the Internet
• No wasting time in transferring data (real-time)
• Decreasing cost by using minimum devices and resources
• More guarantee and security exist when information is sent from source to destination
• No loss of data by putting redundancy backup

Data Communication

• Exchange of data (in the form of 0s and 1s) between two devices via some form of transmission medium (wire or wireless)
• Communicating devices must be part of a communication system
• Effectiveness of a data communication system depends on three fundamental characteristics:
  • Delivery: system must deliver data to the correct destination
  • Accuracy: system must deliver data accurately
  • Timeliness: system must deliver data in a timely manner

Data Communication Components

• Message: information (data) to be communicated
• Sender: device that sends the data message
• Receiver: device that receives the data message
• Medium: transmission medium is the physical path by which a message travels from sender to receiver
• Protocol: set of rules that govern data communication

Network Criteria's

• Performance: measured by transit time and response time
• Number of users: having a large number of concurrent users can slow response time
• Type of transmission medium: defines the speed at which data can travel through a connection
• Hardware: types of hardware included in a network affect both the speed and capacity of transmission
• Software: software used to process data at the sender, receiver, and intermediate nodes also affects network performance

Network Components

• Devices (Interconnecting Devices, End-user devices)
• Physical Media (Wire or Wireless)
• Networking Protocol
• Applications (Services)

Networking Devices

• Network devices are electronic devices that connect computers and various other electronic devices together
• Common devices: HUB, Switches, Routers, Wireless Access Points, Modems etc.

End-User Devices (Computers)

• Clients and Servers
• Client/Server Model: a network structure in which individual computers and devices interact with each other through a central server
• Clients: computers and mobile devices on the network that rely on the server for its resources
• Server: controls access to the hardware, software, and other resources on the network and provides a centralized storage area for programs, data, and information

PEER-TO-PEER

• Each computer, called a peer, has equal responsibilities and capabilities, sharing hardware, data and information with other computers

Networking Media

• Defined as the means by which signals (data) are sent from one computer to another (either by cable or wireless means)

Networking Protocol: TCP/IP

• Protocol: a set of rules that make communication more efficient
• TCP/IP is the most widely used protocol suite

Network Applications (Services)

• E-mail
• Searchable Data (Web Sites)
• E-Commerce
• Internet Telephony (VoIP)
• Video Conferencing
• Chat Groups
• Instant Messengers
• Marketing and sales (booking hotel)
• Financial services (Auto Teller Machine (ATM))
• Manufacturing (multi-user work on project simultaneously)