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Lan networks


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Lan networks

  1. 1. Networking
  2. 2. WALT: Networking Fundamentals Know about: What a network is Network standards Different types of networks What’s required to connect to a network Advantages and disadvantages of being connected to a network© CCI Learning Solutions Inc. 2
  3. 3. What is a Network? Two or more computers connected together to share resources and information© CCI Learning Solutions Inc. 3
  4. 4. What is a Network? Computers connected to network can be any type of computer – Each computer could be configured with different operating system – No restrictions other than having network software understand rules and language needed to recognize computer type and operating system© CCI Learning Solutions Inc. 4
  5. 5. Where the Personal Computer Fits PC most commonly used tool to connect to network – Microprocessor chip is “brains” of PC – Communicates with other components of PC via internal connecting device called “bus” – To communicate with external devices, PC needs interface card To connect PC to network, need interface card for type of network, suitable cable, and appropriate software © CCI Learning Solutions Inc. 5
  6. 6. Networking Standards When two or more computers interconnected to communicate and share resources, you have a network Protocols are rules governing type of cables, interface cards, and electrical signal format Also govern how information flows between computers on network called transport protocols: – indicates how computer needs to send information over network – how receiving computer checks that information was received correctly – how sending computer must address information so it goes to correct destination computer Application level protocols determine how program on one computer communicates with program on another computer © CCI Learning Solutions Inc. 6
  7. 7. Peer-to-Peer Networks Inexpensive and easy to put together Ideal for home and small office networks Called peer-to-peer because all computers have equal authority Protocols included in Microsoft Windows 95/98/ME but several proprietary peer-to-peer network systems available also Windows NT (or higher) has network component built in with more complex protocols to connect computers © CCI Learning Solutions Inc. 7
  8. 8. Client - Server Networks Typical on large networks where one computer (network server) dedicated to controlling network traffic and managing resources Provides better performance and security as server controls who can access what resources and when Also called central server as all files stored here Server can be any type of computer with server software installed, and users clearly identified with access rights Client computer can be any type of computer with network card and appropriate software to connect to server © CCI Learning Solutions Inc. 8
  9. 9. Topologies - Structure Star – All the network devices connected to a central computer which is often used as the file server Ring – Each of the devices on the network is connected in a ring or a loop. (Each machine has a connection to the one previous and the one after it in the loop) Bus – Each of the devices is connected directly to a main communications line, called a bus MESH – All the computers connected to each other Click here to view animations on topologies CJR 2008 9
  10. 10. Star Network Topology Figure 8- 5 CJR 2008 10
  11. 11. Star: Advantages and Disadvantages Advantages of a Star – If one cable fails the other stations are not affected – Consistent performance even under heavy use – Reliable market proven system – No problems with collisions of data since each station has its own cable to the server – Easy to add new stations without disrupting the network Disadvantages of a Star – May be costly to install because of the cable lengths required CJR 2008 11
  12. 12. Bus Network Topology 12 CJR 2008 Figure 8-6
  13. 13. Bus: Advantages and Disadvantages  Advantages of a Bus – Easy and inexpensive to install as it requires the least amount of cable of the network types – Easy to add more stations without disrupting the network  Disadvantages of a Bus – The whole network goes down if the main cable fails at any point – Cable failure is difficult to isolate – Network performance degrades under a heavy load – Information can be transmitted in either CJR 2008 direction and occasionally there is data collision. 13
  14. 14. Ring Network Topology CJR 2008 14 Figure 8-7
  15. 15. Ring: Advantages and Disadvantages Advantages of a Ring – No dependence on a central computer or file server and each node controls communication to and from itself – Transmission around the network is one way only – High data transmission rates are possible Disadvantages of a Ring – If one node breaks down transmission is disrupted CJR 2008 15
  16. 16. Mesh Network Topology CJR 2008 16
  17. 17. Mesh: Advantages and Disadvantages Advantages of a MESH – Communication is not disrupted – Alternative routes to node points/machines – Security – packages can arrive/be sent via many different routes – Backup – with multiple connections it is easier to distribute the data in case of disaster Disadvantages of a MESH – Cost • of cables required to link machines together • Of machines – similar spec machines required at each location to be able to take over – Difficult to install and reconfigure CJR 2008 17
  18. 18. LANs and WANs Difference lies in who is responsible for cabling – LAN network stays within building – WAN if network crosses public street and uses publicly-supplied cabling for part of network When computer or LAN connected to another computer or LAN in another city or country, public portion of WAN represented schematically by “cloud” © CCI Learning Solutions Inc. 18
  19. 19. Connecting to a Network Standard network devices facilitate putting network together Cabling comes in standard lengths complete with appropriate connectors Which options, devices, or software you use depends on needs and requirements for network Variety of connection or cabling options available to access information to or from network – Newer connection types allow the data to be transferred between computer and network to flow much faster© CCI Learning Solutions Inc. 19
  20. 20. Connection/Cabling OptionsCoaxial Wire with center wire surrounded with insulation and then grounded cover of braided wire.Fiber Optics Made up of bundled glass or plastic fibers (threads) to transmit data.Broadband Single wire that can handle multiple paths or channelsWireless Work with radio frequencies for data transmission.Infrared Wireless option works with infrared light waves to transmit data.© CCI Learning Solutions Inc. 20
  21. 21. The Network Interface Card (NIC) To connect to network, PC must have network interface card (NIC) Each NIC has unique number or address and connector appropriate for type of cabling chosen Come in variety of styles and models appropriate for computer type being connected to network© CCI Learning Solutions Inc. 21
  22. 22. The Hub Connect PCs together to form network – Cable from NIC in each PC connects to port on hub – Cable from hub required to connect to network Relatively inexpensive to purchase and install Main disadvantage of hub is all users connected to hub share equal maximum transfer speed © CCI Learning Solutions Inc. 22
  23. 23. Network Segments If network has two or more network interface cards, each card considered a segment Segments allow network traffic to flow faster, depending on which devices are used to manage amount of requests at network© CCI Learning Solutions Inc. 23
  24. 24. The Bridge Connects network segments to handle network requests Do not analyze or re-route messages which makes receiving information faster Will not re-route or re- transmit information if anything is wrong with connection at either end until first transmission received completely © CCI Learning Solutions Inc. 24
  25. 25. The Router Work similar to bridges except examine destination address of information and pass it on appropriate segments only Bridges may be faster than routers but will not check information coming in When installing wireless router to network, be sure to set up encryption security options to prevent unauthorized access from external sources using connection © CCI Learning Solutions Inc. 25
  26. 26. The Switch Works similar to hub except that each user connected to switch has access to full bandwidth Can also be used to join network segments© CCI Learning Solutions Inc. 26
  27. 27. The Firewall Can be physical device or specialized software installed to prevent any unauthorized external access into any network connected to Internet Designed to check any messages that travel through network and ensure it matches specified security requirements set up by company © CCI Learning Solutions Inc. 27
  28. 28. Benefits of Networking Networking does not make individual workstations faster or more powerful! Benefits of networking fall into two main categories: – Communication – Sharing of resources© CCI Learning Solutions Inc. 28
  29. 29. Communicating To send information generated on stand-alone PC requires manual process whereas users on network send information electronically Messages can be stored on network and are not lost if recipient isn’t available when messages sent or received Many communication software allows users to instantly message someone else without using e‑mail – “Real time interaction” – Multiple users can participate in same conversation – Some limitations but can be minor issues in exchange for ability to communicate with each other in real time © CCI Learning Solutions Inc. 29
  30. 30. Sharing Devices Some devices can be expensive to set up on every PC and networking allows devices to be shared – Can be cost savings for capital expenditures as well as productivity time for technical support or maintenance Connecting devices shared by multiple users via network allows Network Administrator to perform updates or troubleshoot problems from server location© CCI Learning Solutions Inc. 30
  31. 31. Sharing Information In network environment, files or folders on any disk can be set up to be shared Whenever group of people want to share information, referred to as workgroup – Group of users who share business documents transfer or save files to common network – Common network becomes centralized server wherein server has control over which files are accessed and which users can use those files Extremely helpful to network administrator for setting up rights or performing maintenance for workgroups© CCI Learning Solutions Inc. 31
  32. 32. Using Dedicated Servers Network – Control network traffic and security – May perform same tasks and contain same information as file or database server File – High speed, high capacity hard drive, usually to handle back-up needs Web – Stores information in web format and information accessed with browser for company intranets Mail – Manages high volume of internal and external e-mail Database – Generally used in complex database applications where many users need to access data at same time © CCI Learning Solutions Inc. 32
  33. 33. Disadvantages of NetworkingDependency Big disadvantage in that organization’s activities depend on network to be up and running – If network fails, users lose access to information and ability to communicate electronically – In some instances can work from local drive, but if company’s information stored and shared from server, cost of downtime may be more expensive in long term© CCI Learning Solutions Inc. 33
  34. 34. Disadvantages of NetworkingExpensive For installation and maintenance If network complex with many users, additional need and expense to employ network administrator Need “disaster and recovery” plan, not just for theft or security breach, but also power outages or potential hardware failure Setting up or upgrading a network server should always be discussed with network administrator or consultant who specializes in networks prior to making any decisions© CCI Learning Solutions Inc. 34
  35. 35. Disadvantages of NetworkingSecurity Risk Every person who logs into server has valid login id, and set up according to company’s standards Every person who logs into server has valid password When setting up new user, ensure name and information about user entered correctly Audit each user to ensure access rights to programs and files are same Requests received for access rights must have signature from corresponding manager Delete users who no longer work for company Do not ever give out passwords © CCI Learning Solutions Inc. 35
  36. 36. Disadvantages of Networking Staff who work with network administrator should have own login id and password set up Firewall set up for Internet connection that has been set up to check user id when sending or receiving messages If access authorized for users outside network, ensure firewall checks these user ids when request received to access network from remote location Restrict any users from being able to delete files from any folder on any network drives Antivirus program installed on server is current and has latest protection files Perform maintenance checks periodically as well to see what activities may have occurred Encourage users to have latest updates of Windows on local computers © CCI Learning Solutions Inc. 36
  37. 37. Disadvantages of NetworkingLoss of Autonomy or Privacy Obliged to work in network environment Privacy may be concern for confidential material “Private” drive set up on network for personal or confidential files but network administrator can still see these files If share computer, even though they log in with their own id, they can still see files on local General business rules dictate that anything you work on a company computer belongs to the company, even though you may work on it on your own time© CCI Learning Solutions Inc. 37
  38. 38. Disadvantages of NetworkingViruses Vulnerable to virus attacks Some viruses, called worm viruses, specifically target servers New viruses being created every day and it becomes more prudent to read screen carefully before automatically opening message or clicking highlighted button on screen All antivirus programs provide a feature to automatically detect in “real time” Remember to run scan of computer on frequent basis and check for updates© CCI Learning Solutions Inc. 38