1. Copyright©2008 N.AlJaffan®KSU1 Chapter 8 Communications and Networks

2. Copyright©2008 N.AlJaffan®KSU2 Chapter 8 Communications and Networks Five general concepts provide the basis for the relationship between the communicating devices:  line configuration.  Topology.  Network Architectures  Internetworks.

3. Copyright©2008 N.AlJaffan®KSU3 Chapter 8 Communications and Networks Line configuration Its refers to the way two or more communication devices attach to a link. Link is the physical communication pathway that transfers data from one device to another. There are two possible line configurations  point-to-point  multipoint

4. Copyright©2008 N.AlJaffan®KSU4 Chapter 8 Communications and Networks

5. Copyright©2008 N.AlJaffan®KSU5 Chapter 8 Communications and Networks Point-to-Point  It is provides a dedicated link between two devices.  The entire capacity of the channel is reserved for transmission between those two devices.

6. Copyright©2008 N.AlJaffan®KSU6 Chapter 8 Communications and Networks Multipoint

7. Copyright©2008 N.AlJaffan®KSU7 Chapter 8 Communications and Networks Multipoint also called multidrop  It is one in which more than two specific devices share a single link.  The capacity of the channel is shared, either spatially or temporally.  If several devices can use the link simultaneously, it is spatially line configuration.  If users must take turns, it is a time-shared line configuration.

8. Copyright©2008 N.AlJaffan®KSU8 Chapter 8 Communications and Networks Topology The term topology refers to the way a network is laid out. There are 5 basic topologies possible:  Mesh  Star  Tree  Bus  Ring

9. Copyright©2008 N.AlJaffan®KSU9 Chapter 8 Communications and Networks Mesh

10. Copyright©2008 N.AlJaffan®KSU10 Chapter 8 Communications and Networks Mesh Every device has a dedicated point –to-point link to every other device.  A fully connected mesh network therefore has n(n-1)/2 physical channels to link n devices.  Every device on the network must have n-1 input/output (I/O) ports.

11. Copyright©2008 N.AlJaffan®KSU11 Chapter 8 Communications and Networks MeshAdvantages 1.Eliminating the traffic problems that can occur when links must be shared by multiple devices. 2.It is robust. it one link becomes unusable, it does not incapacitate the entire system. 3.It is privacy or security. 4.Point-to-point links make fault identification and fault isolation easy.

12. Copyright©2008 N.AlJaffan®KSU12 Chapter 8 Communications and Networks Meshdisadvantages 1.Installation and reconfiguration are difficult. 2.The sheer bulk of the wiring can be greater than the available space can accommodate. 3.The hardware required to connect each link ( I/O ports a cable) can be expensive.

13. Copyright©2008 N.AlJaffan®KSU13 Chapter 8 Communications and Networks Star

14. Copyright©2008 N.AlJaffan®KSU14 Chapter 8 Communications and Networks Star Each device (node) has a dedicated point-to-point link only to a central controller, usually called Hub. Advantages 1.It is less expensive than a mesh topology. 2.It is easy to install and maintain. 3.It is robustness. If one node fails, only that node is affected. 4.Easy fault identification and fault isolation. It has one disadvantage if the hub fails, the entire network is inoperable until the hub is repaired.

15. Copyright©2008 N.AlJaffan®KSU15 Chapter 8 Communications and Networks Tree

16. Copyright©2008 N.AlJaffan®KSU16 Chapter 8 Communications and Networks Tree  Is a variation of a star.  nodes in a tree are linked to a central hub that controls the traffic to the network.  Not every device plugs directly into the central hub.  The majority of devices connect to a secondary hub that in turn is connected to the central hub.

17. Copyright©2008 N.AlJaffan®KSU17 Chapter 8 Communications and Networks Tree  The central hub in the tree is an active hub, which contains a repeater.  The secondary hubs may be active or passive hubs.  A passive hub provides a simple physical connection between the attached devices.

18. Copyright©2008 N.AlJaffan®KSU18 Chapter 8 Communications and Networks Tree  It allows more devices to be attached to a single central hub and can increase the distance a signal can travel between devices.  It allow the network to isolate and prioritize communications from different computers.

19. Copyright©2008 N.AlJaffan®KSU19 Chapter 8 Communications and Networks Bus

20. Copyright©2008 N.AlJaffan®KSU20 Chapter 8 Communications and Networks Bus  Consists of a single central cable, to which all computers and other devices connect.  The bus in a bus network transmits data, instruction and information in both directions.  Bus network are popular on LANs because they are inexpensive and easy to install.

21. Copyright©2008 N.AlJaffan®KSU21 Chapter 8 Communications and Networks Bus  That failure of one device usually does not affect the rest of the bus network.  Difficult reconfiguration and fault isolation.  A fault or break in the bus cable stops all transmission, even between devices on the same side of the problem.

22. Copyright©2008 N.AlJaffan®KSU22 Chapter 8 Communications and Networks Ring

23. Copyright©2008 N.AlJaffan®KSU23 Chapter 8 Communications and Networks Ring A cable forms a closed loop (ring) with all computers and devices arranged along the ring.  Data transmitted on a ring network travels from device to device around the entire ring, in one direction.  If a computer or device on a ring network fails, all devices before the failed device are unaffected, but those after the failed device cannot function.  It can span a larger distance than a bus network, but it is more difficult to install.

24. Copyright©2008 N.AlJaffan®KSU24 Chapter 8 Communications and Networks Hybrid topologies It is a network combines several topologies as subnetworks linked together in a larger topology.

25. Copyright©2008 N.AlJaffan®KSU25 Chapter 8 Communications and Networks Network Architectures Network Architectures  CLINET/SERVER  PEER TO PEER  INTERNET PEER TO PEER (P2P)

26. Copyright©2008 N.AlJaffan®KSU26 Chapter 8 Communications and Networks Network Architectures Network Architectures  CLINET/SERVER one or more computer as a server; the other computers on the network request services from the server. Its provides an efficient means to connect 10 or more computers. Most client/server networks require a person to serve as a network administrator because of the large size of the network

27. Copyright©2008 N.AlJaffan®KSU27 Chapter 8 Communications and Networks Network Architectures Network Architectures  PEER-TO-PEER One type of peer-to-peer network is a simple, inexpensive network that typically connects fewer than10 computer. 1.Each computer, called a peer, has equal responsibilities and capabilities. 2.Sharing hardware as a printer, data, or information with other computers on the peer-to-peer network. 3.Each computer on the network contains both the network operating system and application software. 4.Each computer stores files on its own storage devices.

28. Copyright©2008 N.AlJaffan®KSU28 Chapter 8 Communications and Networks Network Architectures Network Architectures  Internet PEER-TO-PEER ( P2P ) Another type of peer-to-peer. Describe an Internet network. sometimes is called a file sharing network because users with compatible SW and an internet connection copy files from someone else’s HD to their HD. example of networking SW that support P2P are BitTorrent, Grokster, Gunutella and Kazaa, which allow users to swap MP3 music and other files via the web

29. Copyright©2008 N.AlJaffan®KSU29 Chapter 8 Communications and Networks Categories of networks Into which category a network falls is determined its size, ownership, the distance it covers and its physical architecture.  LAN a Local area network  MAN  WAN

30. Copyright©2008 N.AlJaffan®KSU30 Chapter 8 Communications and Networks LAN a Local area network LAN a Local area network  Is a network that connects computers and devices in a limited geographical area such as a home, school computer laboratory, office building, or closely positioned group of buildings.  Is usually privately owned.  It use only one type of transmission media (often are connected via cable ) and topology.  Wireless LAN ( WLAN ) is a LAN that uses no physical wires.

31. Copyright©2008 N.AlJaffan®KSU31 Chapter 8 Communications and Networks

32. Copyright©2008 N.AlJaffan®KSU32 Chapter 8 Communications and Networks MAN a metropolitan area network MAN a metropolitan area network Is a high-speed network that connects local area network in a metropolitan area such as a city or town and handles the bulk of communications activity across that region.  MAN typically includes one or more LANs, but covers a smaller geographic area than a WAN.  Its usually is managed by consortium of users or by single network provider that sell the service to the users.

33. Copyright©2008 N.AlJaffan®KSU33 Chapter 8 Communications and Networks

34. Copyright©2008 N.AlJaffan®KSU34 Chapter 8 Communications and Networks WAN a wide area network Is a network that covers a large geographic area such as country, or the world.  Using a communications channel that combines many types of media such as telephone lines, cables, and radio waves.  A WAN can be one large network or can consist of two or more LANs connected together.  The Internet is the world's largest WAN

35. Copyright©2008 N.AlJaffan®KSU35 Chapter 8 Communications and Networks

36. Copyright©2008 N.AlJaffan®KSU36 Chapter 8 Communications and Networks Internetworks If 2 or more networks are connected, they become an internetwork, or internet. Individual networks are joined into internetworks by the use of interworking devices. These devices, which include routers and gateways. The term internet should not be confused with Internet.  internet used to mean an interconnection of networks.  Internet is the name of specific worldwide network.

37. Copyright©2008 N.AlJaffan®KSU37 Chapter 8 Communications and Networks LAN LAN LAN LAN WAN R R R R R R R R