1. What is a Network? Living Online Lesson 1 Mrs. Elzey

2. Objectives Describe a network. Explain the benefits of a network. List and describe the types of networks. List and describe communications media. Describe communications hardware. Describe communications software. Describe the different network topologies. Describe network architecture. Describe network protocols.

3. Introducing Networks 2 or more computers linked together LAN  Local Area Network  Confined to a limited area WAN  Wide Area Network  Covers a large area

4. Data communication Transferring data from one location to another Components needed:  A sending device; usually a computer  A communication device; usually a modem which converts the data signal into signals supported by the channel (wiring)  A communication channel or path; telephone wire or cables; device used to carry the signal  A receiving device; usually a computer  Communications software

5. Communication components

6. Networks and the Benefits Most have at least 1 server  Manages network resources Many clients  Relies on the server for the resources Benefits  Information sharing – authorized users can use other computers on the network to access and share information and data.  Hardware sharing – one device connected to a network can serve the needs of many users.  Software sharing – all users on the network can access a program from one central location.  Collaborative environment – enables users to work together on group projects

7. Communication Media (wiring or wireless) Used to transfer the data from 1 computer to another Commonly known as the communication channel Physical media  Twisted pair Least expensive Same type used for telephone systems 2 Copper wires twisted around one another One carries the signal the other is grounded to absorb interference  Coaxial Primary type used by cable television now widely used for networks More expensive than twisted pair

8. Wiring or Wireless Fiber optic  Glass tubing  Carries more data  Lighter  Less susceptible to interference  Very fragile and expensive Radio  Must be sent in a straight line Microwaves  Must be sent in a straight line Satellites

9. Network Hardware Modem – acronym for Modulate-Demodulate  Means to convert analog signals to digital and vise- versa  Allows data to be sent over telephone lines Cable modem Network Interface Card (NIC) – controls the sending and receiving of data between PCs and LANs Hub – a junction where data arrives from 1 or more directions and forwarded out in 1 or more directions

10. Network Hardware (cont’d) Bridge – a computer that connects 1 LAN to another LAN Gateway – software and hardware that links 2 different types of networks that use different protocols Router – directs the path to send data

11. LAN Confined to a limited geographical area 2 types:  Client/Server: 1 or more computers on the network acts as a server The server manages network resources  Printer: manages the printing  Database: manages the database files High speed computer with lots of storage space Network O/S and applications are stored on the server All other computers connected are clients. They share the resources on the server.  Peer-to-Peer All computers are equal People determine which files they want to share on their computer with others. Easy to setup and manage

12. Client/Server  Client/Server: 1 or more computers on the network acts as a server The server manages network resources  Printer: manages the printing  Database: manages the database files High speed computer with lots of storage space Network O/S and applications are stored on the server All other computers connected are clients. They share the resources on the server.

13. Peer to Peer  Peer-to-Peer All computers are equal People determine which files they want to share on their computer with others. Easy to setup and manage

14. WAN Usually consists of 2 or more LANs and are connected by routers. Largest WAN known is the Internet.

15. Network Topologies

16. Network Topologies:Linear Bus All devices are connected to and share a master cable  There is no host computer  Data is transmitted in both directions  Easy to install and inexpensive

17. Network Topologies:Ring Devices are connected in a circle.  Each computer is connected to an adjoining device on either side  Data travels around the ring from device to device.  More difficult to install and manage and more expensive.  Provides faster transmission speeds and can span large distances.

18. Network Topologies: Tree A tree topology combines characteristics of linear bus and star topologies. It consists of groups of star- configured workstations connected to a linear bus backbone cable Tree topologies allow for the expansion of an existing network, and enable schools to configure a network to meet their needs.

19. Network Topologies: Star All devices are connected to a central hub or computer.  All data from a computer goes to the hub then back out.  Easy to install and manage  Can cause bottleneck because data must pass through the hub  Requires more cabling

20. Communication Protocols

21. A protocol is… An agreed-on set of rules and procedures  Example: Procedure for coming into class Procedure for leaving class Rules for driving  Staying on the right-hand side of the road  Stopping at a red light

22. Communication protocol An agreed-on set of rules and procedures for transmitting data between 2 or more devices.  How the sending device indicates it has finished sending the message  How the receiving device indicates it has received the message  The type of error checking to be used

23. Communication Protocol Many have been developed, but with networking and LANs, the 2 most popular are:  Ethernet  Token Ring Internet Protocol  TCP/IP

24. Communication Protocols Ethernet: 1 st approved industry standard  Most popular  Based on the bus topology  Can work with star  Supports data transfer rates of up to 10 megabytes per second (Mbps)  2 versions Fast Ethernet Gigabit Ethernet

25. Communication Protocols Token ring: 2 nd most widely used  Computers are arranged in a circle  A special signal travels around the ring  A computer on the ring catches the “token” to send a message  Attaches a message to it and then lets it travel around the network

26. Communication Protocol TCP/IP: acronym for Transmission Control Protocol/Internet Protocol  Used by LANs and WANs  Adopted as a standard to connect hosts (servers or computers) on the Internet.

27. LAN Topologies Summary Physical Topology Common CableCommon Protocol Linear BusTwisted Pair Coaxial Fiber Ethernet (PC) LocalTalk(Apple) StarTwisted Pair Fiber Ethernet LocalTalk Star-Wired RingTwisted PairToken Ring RingTwisted Pair Coaxial Fiber Ethernet

28. Network Operating Systems 2 types are needed  Desktop Windows OS Mac OS  Network Windows Unix Novell