1. NETWORKING FUNDAMENTALS

2. Network+ Guide to Networks, 4e2

3. 3 Why Use Networks? Network: group of computers and other devices that are connected by some type of transmission media Advantages of using networks over standalone computers: –Networks enable multiple users to share the network’s resources (devices and data) –Networks allow you to manage, or administer, resources on multiple computers from a central location

4. Network+ Guide to Networks, 4e4 NETWORK ARCHITECTURE Peer-to-peer Networks Every computer can communicate directly with every other computer By default, no computer has more authority than another Every computer is capable of sending and receiving information to and from every other computer

5. Network+ Guide to Networks, 4e5 Peer-to-peer Networks Figure 1-1: Resource sharing on a simple peer-to-peer network

6. Network+ Guide to Networks, 4e6 Client/Server Networks Server: central computer used to facilitate communication and resource sharing between other computers on the network (called clients) Client/server network: uses a server to enable clients to share data, data storage space, and devices To function as a server, a computer must be running a network operating system (NOS)

7. Network+ Guide to Networks, 4e7 Client/Server Networks (continued) Figure 1-2: Resource sharing on a client/server network

8. Network+ Guide to Networks, 4e8 Client/Server Networks (continued) Advantages of using client/server networks over peer-to-peer networks: –User logon accounts and passwords can be assigned in one place –Access to multiple shared resources can be centrally granted to a single user or groups of users –Problems can be tracked, diagnosed, and often fixed from one location

9. Network+ Guide to Networks, 4e9 Client/Server Networks (continued) Advantages of using client/server networks over peer-to-peer networks (continued): –Servers are optimized to handle heavy processing loads and dedicated to handling requests from clients, enabling faster response time –Because of their efficient processing and larger disk storage, servers can connect more than a handful of computers on a network

10. Network+ Guide to Networks, 4e10 TYPES OF NETWORKS Local area network (LAN): confined to a relatively small space, such as a building or an office Metropolitan area network (MAN): larger than a LAN; connects clients and servers from multiple buildings Wide area network (WAN): connects two or more geographically distinct LANs or MANs

11. Network+ Guide to Networks, 4e11 LANs, MANs, and WANs (continued) Figure 1-4: A simple WAN

12. BENEFITS OF A NETWORK Information sharing: Authorized users can use other computers on the network to access and share information and data. This could include special group projects, databases, etc. Hardware sharing: One device connected to a network, such as a printer or scanner, can be shared by many users. Software sharing: Instead of purchasing and installing a software program on each computer, it can be installed on the server. All of the users can then access the program from a single location. Collaborative environment: Users can work together on group projects by combining the power and capabilities of diverse equipment. Network+ Guide to Networks, 4e12

13. HOW ARE NETWORKS CATEGORIZED? Networks are usually classified using three properties: Topology Protocol Architecture Network+ Guide to Networks, 4e13

14. NETWORK TOPOLOGIES Network Topology (or layout) – refers to the way computers and peripherals are configured to form networks –Bus topology – all computers are linked by a single line of cable –Star topology – multiple computers and peripheral devices are linked to a central computer, called a host –Ring topology – each computer or workstation is connected to two other computers, with the entire network forming a circle –Hybrid topology – combine network layout types to meet their needs Network+ Guide to Networks, 4e14

15. NETWORK/COMMUNICATION PROTOCOLS A protocol is simply an agreed-on set of rules and procedures for transmitting data between two or more devices. Features determined by the protocol are: –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. Network+ Guide to Networks, 4e15

16. Signals and Protocols A data network is a group of computers connected by a network medium. The network medium carries signals between computers. Signals reduce complex information to the simplest possible form. Computers communicate by using a language called a protocol. Network+ Guide to Networks, 4e16

17. Protocol Services Packet acknowledgment Segmentation Flow control Error detection Error correction Data compression Data encryption Network+ Guide to Networks, 4e17

18. The OSI Reference Model Network+ Guide to Networks, 4e18

19. Data Encapsulation Network+ Guide to Networks, 4e19

20. The OSI Reference Model Network+ Guide to Networks, 4e20

21. NETWORKING HARDWARE AND SOFTWARE Hub – electronic device (with a number of ports) used in a LAN to link groups of computers Repeaters (also called amplifiers) – electronic devices that receive signals and amplify and send them along the network Routers - electronic devices used to ensure messages are sent to their intended destinations Gateway – consists of hardware and/or software that allows communications between dissimilar networks Bridge – consists of hardware and/or software that allows communication between two similar networks Network+ Guide to Networks, 4e21

22. REPEATERS A common problem in the networking world is that of weakening electrical signals. Electrical signals traveling through wires (such as copper wires used in most networks) This effect limits the lengths of the cable that can be used. when there is a need to connect two computers at a larger distance. A repeater is connected to two cable segments. Any electrical signal reaching the repeater from one segment, will be amplified and retransmitted to the other segment. An illustration of a repeater at work The electrical signal entering the repeater at one end is weakened.The repeater amplifies the electrical signals and resends the data. 22

23. ROUTERS Network+ Guide to Networks, 4e23 Routers connect two or more networks and forward data packets between them. When data arrives from one of the segments, the router decides, according to it's routing table, to which segment to forward that data.

24. MODEMS 24 A modem is a device that converts digital data originating from a terminal or computer, to analog signals used by voice communication networks such as the telephone system. At one end, modems convert the digital pulses to audible tones and convert audio tones back to digital pulses at the other. An illustration of data sent using a modem and a regular telephone line. A modem is a device that converts digital data originating from a terminal or computer, to analog signals used by voice communication networks such as the telephone system. At one end, modems convert the digital pulses to audible tones and convert audio tones back to digital pulses at the other.

25. EXAMPLE OF FIREWALL Firewalls are systems that establish access control policies among networks. They can block information from entering a network or from getting out of that network, they can permit different users to perform different kinds of operations, according to the user's authorizations. Network+ Guide to Networks, 4e25

26. Network+ Guide to Networks, 4e26 Elements Common to Client/Server Networks

27. Network+ Guide to Networks, 4e27 Elements Common to Client/Server Networks Figure 1-8: Examples of network transmission media

28. Network+ Guide to Networks, 4e28 How Networks Are Used Network services: functions provided by a network File services –Capability of a server to share data files, applications, and disk storage space –File server Print services: used to share printers across a network

29. Network+ Guide to Networks, 4e29 How Networks Are Used Communications services –Allow remote users to connect to the network –Remote access server (also known as communications server or access server) Mail services –Coordinate the storage and transfer of e-mail between users on a network –Mail server

30. Network+ Guide to Networks, 4e30 How Networks Are Used Internet services –Supplying Web pages, file transfer capabilities, Internet addressing schemes, security filters, and a means for directly logging on to other computers on the Internet –Web server Management services: centrally administer management tasks on the network –Traffic monitoring and control –Load balancing