Lecture 6: Networking J. S. Chou, P.E., Ph.D. National Chung Cheng University

1. Lecture 6: Networking J. S. Chou, P.E., Ph.D. National Chung Cheng University

2. Human Communication Messages Human communication involves the sharing of information between senders and receivers. The information is shared in the form of a message Sender Initiates the message by formulating the message content in the brain and coding the message in a form that can be communicated to the receiver (e.g. voice) Receiver Uses their receiving mechanism (e.g. eyes, ears) to receive the encoded message and then attempts to decode its content or requests the message be resent Communication Pathway

3. Human Communication Example

4. Requirements for Communication (Computer) Senders and Receivers There must a be a sender and a receiver with something to share via a message to facilitate communication Communication Medium A medium must exist between the sender and receiver over which the message travels (e.g., a cable) Protocols Procedures, rules, or standards must be followed by computers when sending or receiving data

5. Communication (Human versus Computer)

6. Computer Networks Centralized Computing (1970s) The centralized computing model utilizes a central computer (mainframe) connected to terminals with all processing being done on the central computer Distributed Computing(1980s) The use of small computers networked together allowing users to perform a subset of tasks that in aggregate are equal to that of a centralized computer while also being able to share information between those computers Collaborative Computing(1990s) A synergistic form of distributed computing in which two or more networked computers are used to accomplish a common processing task where they are not only sharing data but also sharing processing responsibilities

7. Types of Computing Distributed Computing Centralized Computing Collaborative Computing

8. Types of Networks • Networks • Most networks utilize a combination of computing models that have evolved over time and are connected by one or more of the following network types: • Private Branch Exchange (PBX) • Local Area Network (LAN) • Wide Area Network (WAN) • Global Networks • Enterprise Network • Value-added Network (VAN) • Metropolitan Network (MAN) • Personal Area Network (PAN)

9. Private Branch Exchange PBX A telephone system serving a location by connecting one telephone line to another then to an outside telephone network. Can also connect PCs, fax, but at low phone- cable speeds

10. Network Types – Local Area Network Local Area Network A computer network that spans a relatively small area allowing all computer users to connect with each other to share information and peripheral devices (e.g., printers)

11. Types of Networks – Wide Area Networks (WAN) Wide Area Networks (WANs) A computer network that spans a relatively large area and is typically used to connect two or more LANs using different kinds of hardware and transmission media to cover large distances efficiently Global A WAN that spans multiple countries and may include the networks of several organizations (e.g. the Internet) Value-added Network (VAN) A medium-speed, third-party-managednetwork that is economical as it is shared by multiple customerorganizations that lease lines rather than investing in dedicated network equipment

12. Types of Networks – Wide Area Networks (WAN) Enterprise Network & MAN Enterprise A WAN that is the result of connecting the disparate networks of a single organization Metropolitan Area (MAN) A WAN network of limited geographic scope, typically in a city-wide area that combines both LAN and high-speed fiber-optic technologies

13. Types of Networks – Personal Area Network (PAN) Personal Area Network An emerging technology that uses wireless communication to exchange data between commuting devices using short-range radio communication (Bluetooth), typically within an area of ten meters Bluetooth Is the enabling technology of the Personal Area Network and is a specification for personal networking of desktop computers, mobile phones, pagers, portable stereos, and other handheld devices developed by its founders Ericsson, IBM, Intel, Nokia, and Toshiba

14. Networking Fundamentals – Servers and Clients Network A network consists of three separate components: servers, clients and peers Server Any computer on a network that makes access to files, printing, communication, and other services available to users on the network Client Any computer, such as a user’s workstation or a PC on the network, or software application such as word processing program that uses services provided by the server. A client only requests service and usually has only one user

15. Networking Fundamentals – Peers Peer A computer that may both request and provide services Peer-to-Peer Networks (P2P) Enables any computer or device on the network to provide or request services with all peers having equivalent capabilities and responsibilities (e.g., Napster)

16. Networking Fundamentals - Network Services Network Services The capabilities that networked computers share through the multiple combinations of hardware and software File Services (a) The capabilities that networked computers share through the multiple combinations of hardware and software Print Services (b) The capabilities used to control and manage user’s access to network printers, plotters, fax equipment, etc.

17. Networking Fundamentals - Network Services Message Services (c) The capabilities that include storing, accessing, and delivering of text, binary, graphic, digitized video and audio data Application Services (d) The capabilities that run software for network clients and enable computers to share processing power Network Operating System (NOS) Is software that controls the network enabling computers to communicate by enabling network services

18. Networking Fundamentals – Media (Wireless) • Wireless • A communication mechanism that has no physical transmission media, hence the name wireless, that works by transmitting electromagnetic signals through the air. Types of wireless media include: • Infrared line of sight • High-frequency radio • Microwave methods Infrared Line of Sight Uses high-frequency light waves to transmit data on an unobstructed path between nodes – computers or some other device such as a printer – on a network up to 24.4 meters (i.e. most electronics remotes use this infrared light) and are susceptible to attenuation, EMI, eavesdropping, high-intensity light, and smoke

19. Networking Fundamentals – Media (Wireless) High-Frequency Radio A fast transmission medium for distances up to 40 kilometers, depending on obstructions. Attenuation is very low but is susceptible to EMI and eavesdropping. Applications of this technology include pagers, cellular phones, and Wi-Fi Pagers A one way, wireless messaging system in multiple types

20. Networking Fundamentals – Media (Wireless) Cellular Phone A two-way wireless communication that assigns unique frequencies to calls and can transmit in analog or digital

21. Networking Fundamentals – Media (Wireless) Wireless LANs or Wireless Fidelity (Wi-Fi) Based on a standard called 802.11, this technology enables multiple computers to share Internet access, files, and peripheral devices

22. Networking Fundamentals – Media (Wireless) Wireless Media Benefits and Drawbacks Comparisons of Wireless Media

23. Network Hardware and Software (Hardware) Modem (Modulator/Demodulator) Enables computers to connect and transmit data over phone lines by converting the sending computer’s digital signals to analog and back again for the receiving computer

24. Network Hardware and Software (Hardware) Router An intelligent device used to connect two or more individual networks. When it receives a signal, it looks up the address and passes it to the appropriate network Brouter Short for bridge router and provides the functions of both Channel Service Unit A device that acts as a buffer between a LAN and a public carriers WAN to ensure signals placed on the public lines are appropriately timed and formed for the network Gateways This device performs a protocol conversion so that different networks can communicate even though they speak different languages