1. Introduction and Overview
Chapter 1
Introduction and Overview
© Bobby Hoggard, Department of Computer Science, East Carolina University
These slides may not be used or duplicated without permission

2. Creation of the Internet
1980: Birth of the Internet
Started as a small research project with a few sites a few universities and the US Dept. of Defense
Two major goals of the project:
Create communication between different types of systems
Create a system to allow parts of it to communicate, even when other parts fail

3. Why is Networking Complex?
Must have ways to manage network traffic
Must have ways to manage interference from outside sources
Being able to recognize different parts
Many technologies exists
Many ways to combine and connect the parts
Differing communication means (some standards incompatible with others)
Lack of consistency
Technical terms are often confused with names of products
Misuse of terms (ex: server)

4. 5 Key Aspects of Networking
Network Applications and Programming
Data Communications
Packet Switching and Networking Technologies
Internetworking with TCP/IP
Additional Concepts and Technologies

5. Network Apps & Programming
Network Application: application software that provides network services
Applications include: , file transfer, web browsing, voice telephone calls, distributed databases, teleconferencing
An application program on one device communicates with an application program on another device
Application
Data
Application
Data

6. Network Apps & Programming
Applications offer a specific service and interface, but share a single communication network
Programmers only need to learn the network interface and some basic functions
The same functions are used in all networking applications
Application programs can be written without understanding the hardware/software that transfers the data however…
Understanding the underlying network can help you write applications that are more reliable, correct and efficient

7. Data Communications
The study of low-level technologies used to send data over a physical network
How to use physical phenomena to transfer information
Three major communication methods:
Wires (uses electricity)
Fiber optics (uses light)
Wireless (uses radio waves)

8. Packet Switching
Breaking data into smaller units for easier, and more reliable transmission, and more efficient use of the network
Packet switching evolved from traditional telephone switching circuits
Understanding how they work is vital to understanding how packet switching helps

9. Traditional Switching
Telephones have a dedicated connection line to the telephone company central office
Central offices are connected to each other through multiple connections and to bigger offices

10. Traditional Switching
Each telephone co. office finds the best available circuit
A dedicated connection is made between sender and receiver
Once those connections have been made, they can’t be used to make other connections until this communication has finished

11. Packet Switching
Data is divided into small packets and sent individually
Packets can take various routes to get to the destination, and may arrive out of order H E L L O

12. Packet Switching Connections are not held for long periods of time
As such, this frees the circuits so other devices can use them, making more efficient use of the circuits H E L L O J A V A

13. Internetworking with TCP/IP
A set of protocols that govern communication across the Internet
Adapts as it travels across different types of network
Creates a “virtual” networking system
Defines network independent packets and addressing
Allows new technologies to be incorporated, without requiring the replacement of old technologies

14. Public vs. Private Networks
The Internet consists of both
Public networks
A service available to subscribers
Anyone paying for the service can have access
A service provider provides access
Private networks
Controlled by one group of people
Network use is restricted
Private networks can include circuits leased from a public provider

15. Types of Private Networks
Consumer
Could be as simple as connecting a printer to a computer
Small Office / Small Home (SOHO)
Involves several devices usually confined to one small area/room
Small-to-Medium Size Business (SMB)
Several networks connected together throughout a building
Large Enterprise
Several buildings connected (each being a small/med business)
Buildings can be geographically separated

16. Interoperability & Standards
The ability of two devices to communicate without misunderstanding
Standards (protocols) specify details of how to communicate
How electrical signals are used to represent data
How to initiate communication
Format of the message
What to do when an error occurs

17. Protocol Suites and Layers
Protocols must be developed to ensure that the system is complete and works efficiently
Protocols are designed in sets called families or suites
Each protocol in a suite handles one aspect of communication

18. TCP/IP Protocol Suite Application Transport Internet Network Interface
Layer 5
Application
Layer 4
Transport
Layer 3
Internet
Layer 2
Network Interface
Layer 1
Physical
“All Time Is Nearly Passing”

19. TCP/IP Protocol Suite
Data originates at the application level because one application wants to communicate with another
Data is passed down through the layers
Each layer adds a header to help the opposing layer identify and process the data
Once data reaches the bottom, it is physically transmitted to the receiving device
The received packet is passed back up through the layers, with each layer stripping off it’s header

20. Goal: Get the data from the sender application to the receiver application
Transport
Internet
Network Interface
Physical
Application
Transport
Internet
Network Interface
Physical
data
data

21. Goal: Get the data from the sender application to the receiver application
Transport
Internet
Network Interface
Physical
Application
Transport
Internet
Network Interface
Physical
data
data

22. Application Transport Internet Network Interface Physical
Format of the message
How applications interact with each other
Transport
How fast can the receiver receive data
How to avoid network congestion
Make sure packets arrive in correct order
Internet
Internet addressing structure
Format of Internet packets
Dividing large packets into smaller ones Error reporting
Network Interface
Hardware addressing
Packet size for the specific physical network
Protocols for the specific physical network
Physical
Electrical properties, Radio frequencies, etc.
Signaling

23. 7-Layer OSI Model Application Presentation Session Transport Network
Data Link
Layer 1
Physical
“All People Seem To Need Data Processing”