1. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Introduction Chapter 1

2. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Uses of Computer Networks Business Applications Home Applications Mobile Users Social Issues

3. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Business Applications of Networks A network with two clients and one server.

4. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Business Applications of Networks (2) The client-server model involves requests and replies.

5. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Home Network Applications Access to remote information Person-to-person communication such BitTorrent Interactive entertainment Electronic commerce

6. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Home Network Applications (2) In peer-to-peer system there are no fixed clients and servers.

7. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Home Network Applications (3) Some forms of e-commerce.

8. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Mobile Network Users Combinations of wireless networks and mobile computing.

9. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Network Hardware Local Area Networks Metropolitan Area Networks Wide Area Networks Wireless Networks Home Networks Internetworks

10. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Broadcast Networks (2) Classification of interconnected processors by scale.

11. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني PANs (Personal Area Networks PANs (Personal Area Networks) let devices communicate over the range of a person. A common example is a wireless network that connects a computer with its peripherals such as short-range wireless network called Bluetooth

12. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Local Area Networks Two broadcast networks (a) Bus (b) Ring A LAN is a privately owned network that operates within and nearby a single building like a home, office or factory.

13. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Examples of LAN Devices

14. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Metropolitan Area Networks A metropolitan area network based on cable TV. A MAN (Metropolitan Area Network) covers a city Examples:  cable television networks  IEEE 802.16 and is popularly known as WiMAX.

15. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Wide Area Networks Relation between hosts on LANs and the subnet.

16. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Wide Area Networks (2) A stream of packets from sender to receiver.

17. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Wireless Networks Categories of wireless networks: System interconnection Wireless LANs Wireless WANs

18. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Wireless Networks (2) (a) Bluetooth configuration (b) Wireless LAN

19. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Wireless Networks (3) (a) Individual mobile computers (b) A flying LAN

20. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Home Network Categories Computers (desktop PC, PDA, shared peripherals Entertainment (TV, DVD, VCR, camera, stereo, MP3) Telecomm (telephone, cell phone, intercom, fax) Appliances (microwave, fridge, clock, furnace, airco) Telemetry (utility meter, burglar alarm, babycam).

21. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Network Software Protocol Hierarchies Design Issues for the Layers Connection-Oriented and Connectionless Services Service Primitives The Relationship of Services to Protocols

22. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Network Software Protocol Hierarchies Layers, protocols, and interfaces.

23. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Protocol Hierarchies (2)

24. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Protocol Hierarchies (3) Example information flow supporting virtual communication in layer 5.

25. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Design Issues for the Layers AddressingAddressing Error ControlError Control Flow ControlFlow Control MultiplexingMultiplexing RoutingRouting Resource AllocationResource Allocation ConfidentialityConfidentiality AuthenticationAuthentication

26. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Connection-Oriented and Connectionless Services Six different types of service.

27. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Service Primitives Five service primitives for implementing a simple connection-oriented service.

28. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Service Primitives (2) Packets sent in a simple client-server interaction on a connection- oriented network.

29. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Services to Protocols Relationship The relationship between a service and a protocol.

30. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Reference Models The OSI Reference Model The TCP/IP Reference Model A Comparison of OSI and TCP/IP A Critique of the OSI Model and Protocols A Critique of the TCP/IP Reference Model

31. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  Reference Models The OSI reference model.

32. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  The Physical Layer The physical layer is concerned with transmitting raw bits over a communication channel. making sure that when one side sends a 1 bit it is received by the other side as a 1 bit, not as a 0 bit. what electrical signals should be used to represent a 1 and a 0, how many nanoseconds a bit lasts, how many pins the network connector has, and what each pin is used for.

33. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  The Data Link Layer The main task of the data link layer having the sender break up the input data into data frames (typically a few hundred or a few thousand bytes) and transmit the frames sequentially. If the service is reliable, the receiver confirms correct receipt of each frame by sending back an acknowledgement frame. let the transmitter know when the receiver can accept more data. Broadcast networks have an additional issue in the data link layer: how to control access to the shared channel. A special sublayer of the data link layer, the medium access control sublayer, deals with this problem.

34. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  The Network Layer The network layer controls the operation of the subnet. determining how packets are routed from source to destination. They can also be determined at the start of each conversation, for example, a terminal session, such as a login to a remote machine, determined anew for each packet to reflect the current network load. If too many packets are present in the subnet at the same time, they will get in one another’s way, forming bottlenecks. Handling congestion is also a responsibility of the network layer, quality of service provided (delay, transit time, jitter, etc.) is also a network layer issue.

35. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  The Transport Layer The basic function of the transport layer is to accept data from above it, split it up into smaller units if need be, pass these to the network layer, ensure that the pieces all arrive correctly at the other end. The transport layer also determines what type of service to provide to the session layer, The most popular type of transport connection is an error-free point-to-point channel that delivers messages or bytes in the order in which they were sent. The type of service is determined when the connection is established. The transport layer is a true end-to-end layer; it carries data all the way from the source to the destination.

36. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  The Session Layer The session layer allows users on different machines to establish sessions between them. Sessions offer various services, including dialog control (keeping track of whose turn it is to transmit), synchronization (checkpointing long transmissions to allow them to pick up from where they left off in the event of a crash and subsequent recovery).

37. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  The Presentation Layer Unlike the lower layers, which are mostly concerned with moving bits around, the presentation layer is concerned with the syntax and semantics of the information transmitted. In order to make it possible for computers with different internal data representations to communicate, the data structures to be exchanged can be defined in an abstract way, along with a standard encoding to be used ‘‘on the wire.’’ The presentation layer manages these abstract data structures and allows higher-level data structures (e.g., banking records) to be defined and exchanged.

38. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  The Application Layer The application layer contains a variety of protocols that are commonly needed by users. One widely used application protocol is HTTP (HyperText Transfer Protocol), which is the basis for the World Wide Web. When a browser wants a Web page, it sends the name of the page it wants to the server hosting the page using HTTP. The server then sends the page back. Other application protocols are used for file transfer, electronic mail, and network news.

39. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Reference Models (2) The TCP/IP reference model.

40. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  The Link Layer The lowest layer in the model, the link layer describes what links such as serial lines and classic Ethernet must do to meet the needs of this connectionless internet layer. It is not really a layer at all, in the normal sense of the term, but rather an interface between hosts and transmission links.

41. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  The internet layer The internet layer is corresponding roughly to the OSI network layer. Its job is to permit hosts to inject packets into any network and have them travel independently to the destination (potentially on a different network). The internet layer defines an official packet format and protocol called IP (Internet Protocol), plus a companion protocol called ICMP (Internet Control Message Protocol) that helps it function. The job of the internet layer is to deliver IP packets where they are supposed to go. Packet routing is clearly a major issue here, as is congestion (though IP has not proven effective at avoiding congestion).

42. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  The Transport Layer the transport layer. It is designed to allow peer entities on the source and destination hosts to carry on a conversation, just as in the OSI transport layer. Two end-to-end transport protocols have been defined here. The first one, 1.TCP(Transmission Control Protocol), is a reliable connection- oriented protocol that allows a byte stream originating on one machine to be delivered without error on any other machine in the internet.  It segments the incoming byte stream into discrete messages and passes each one on to the internet layer.  At the destination, the receiving TCP process reassembles the received messages into the output stream.  TCP also handles flow control to make sure a fast sender cannot swamp a slow receiver with more messages than it can handle.

43. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني 2.UDP (User Datagram Protocol), is an unreliable, connectionless protocol for applications that do not use sequencing or flow control. It is also widely used for one-shot, client-server-type request- reply queries and applications in which prompt delivery is more important than accurate delivery, such as transmitting speech or video.

44. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  The Application Layer Applications simply include any session and presentation functions that they require. It contains all the higher-level protocols. The early ones included  virtual terminal (TELNET),  file transfer (FTP),  electronic mail (SMTP).  Domain Name System (DNS), for mapping host names onto their network addresses,  HTTP, the protocol for fetching pages on the World Wide Web,  RTP, the protocol for delivering real-time media such as voice or movies

45. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني Reference Models (3) Protocols and networks in the TCP/IP model initially.

46. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  Asynchronous transfer mode (ATM) Asynchronous transfer mode (ATM) is a switching technique used by telecommunication networks that uses asynchronous time-division multiplexing to encode data into small, fixed-sized cells. This is different from Ethernet or Internet, which use variable packet sizes for data or frames. A cell is defined as a small, fixed-size block of information.

47. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  Why using ATM cells? Asynchronous transfer mode was designed with cells in mind. This is because voice data is converted to packets and is forced to share a network with burst data (large packet data) passing through the same medium. So, no matter how small the voice packets are, they always encounter full-sized data packets, and could experience maximum queuing delays. This is why all data packets should be of the same size. ATM creates fixed routes between two points before data transfer begins, which differs from TCP/IP, where data is divided into packets, each of which takes a different route to get to its destination.

48. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني ATM Virtual Circuits A virtual circuit.

49. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  ATM Architecture ATM is a cell-switched network consists of the following components: 1.The user access devices, called the endpoints, are 2.connected through a user-to-network interface (UNI) to the switches inside the network. 3.The switches are connected through network-to-network interfaces (NNIs).

50. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  ATM Architecture

51. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني  Virtual Connections Connection between two endpoints is accomplished through transmission paths, virtual paths, and virtual circuits. 1.A transmission path (TP) is the physical connection (wire, cable, satellite, and so on) between an endpoint and a switch or between two switches. A transmission path is divided into several virtual paths. 2.A virtual path (VP) provides a connection or a set of connections between two switches. Cell networks are based on virtual circuits (VCs). 3.All cells belonging to a single message follow the same virtual circuit and remain in their original order until they reach their destination.

52. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني ATM Virtual Circuits (2) An ATM cell.

53. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني The ATM Reference Model The ATM reference model.

54. نظام المحاضرات الالكترونينظام المحاضرات الالكتروني The ATM Reference Model (2) The ATM layers and sublayers and their functions.