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Aleksandra Smiljani ć aleks@ece.sunysb

Aleksandra Smiljani ć aleks@ece.sunysb.edu. Local and Wide Area Networks. Course Outline: First Third. • Introduction to networking • Transmission media – Air, twisted pairs, coaxial cables, optical fibers • Data link techniques – Error detection and correction codes

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Aleksandra Smiljani ć aleks@ece.sunysb

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  1. Aleksandra Smiljanićaleks@ece.sunysb.edu Local and Wide Area Networks

  2. Course Outline: First Third • Introduction to networking • Transmission media – Air, twisted pairs, coaxial cables, optical fibers • Data link techniques – Error detection and correction codes –Sliding window protocol –HDLC, PPP • Medium access protocols –Ethernet, FDDI, RPR –DOCSIS – Wireless LAN

  3. Course Outline: Second Third • Switches and QoS –Circuit switches: Clos structure –Packet switch architectures –Weighted fair queueing (WFQ), random early detection (RED) –High-capacity packet switches • Bridging –Learning bridges –Spanning tree algorithm

  4. Course Outline: Third Third • Routing – Connection-oriented and connectionless networks –Distance vector routing –Link state routing –OSPF, RIP • Transport end-to-end protocols –TCP, UDP • Applications –FTP, Telnet, Email, DNS, WWW, Multimedia • Network Security

  5. Introduction to Networking

  6. Uses of Computer Networks • Business Applications • Home Applications

  7. Business Applications • Sharing resources • Common databases for customer records, inventory, accounts • E-commerce • Video-conferencing • Disseminating the information, and coordination

  8. Home Applications • Getting the remote information • Person-to-person information • E-commerce • Entertainment • E-flea

  9. Application Types • Some forms of e-commerce.

  10. Client-Server Communication • A network with two clients and one server.

  11. Client-Server Communication • The client-server model involves requests and replies.

  12. Peer-to-Peer Communication • In peer-to-peer system there are no fixed clients and servers.

  13. Mobile and Wireless Applications • Combinations of wireless networks and mobile computing.

  14. Wireless Applications • Portable offices • Trucks, taxis, police need to communicate • Help with orientation in the area • Car rental return • M-commerce • Status of the machines

  15. Network Types • Local Area Networks • Metropolitan Area Networks • Wide Area Networks • Wireless Networks • Home Networks • Internetworks

  16. Network Types • Classification of interconnected processors by scale.

  17. Local Area Networks • Two LANs • (a) Bus-broadcast • (b) Ring

  18. Metropoliten Area Networks Switch • Two MANs • (a) Star-switched • (b) Ring

  19. Metropolitan Area Networks • A metropolitan area network based on cable TV.

  20. Wide Area Networks Circuit switch • Relation between hosts on LANs and the subnet.

  21. Wide Area Networks • A stream of packets from sender to receiver.

  22. Wireless Networks • Categories of wireless networks: • System interconnection • Wireless LANs • Wireless WANs

  23. Wireless Networks • (a) Bluetooth configuration • (b) Wireless LAN

  24. Wireless Networks • (a) Individual mobile computers • (b) A flying LAN

  25. 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).

  26. Network Hardware • Transmission medium • Transceivers: transmitters and receivers on the point-to-point connections • Multiplexers, demultiplexers • Packet and circuit switches • Bridges • Routers • Servers, gateways, management units

  27. Transmission Medium • Air: different frequency bands • Wires: twisted pairs • Coaxial cables • Optical fibers

  28. Transceivers • Transmitters perform modulation and coding to provide efficient and reliable communication. • Receivers perform the reverse operations. • Depending on the medium transceivers are electronic devices, antenas, or lasers and photodiodes.

  29. Multiplexers and Demultiplexers • Multiplexers receive multiple lower bit-rate streams of data and according to some rule transmit the higher bit-rate stream of data. • Demultiplexers do the opposite.

  30. Circuit and Packet Switches • It does not make sense to connect every user with every other user in the network. • Circuit and packet switches connect multiple inputs to multiple outputs. • In circuit switches, the configuration pattern changes on a slow time scale. • In packet switches, the configuration changes on a packet-per-packet basis.

  31. Servers, Gateways, etc. • Servers store various kinds of information for users, for example DNS databases, e-mails, web pages and provide it to the users. • Gateways convert data format, and negotiate QoS with the network.

  32. Network Software • Protocol Hierarchies • Design Issues for the Layers • Connection-Oriented and Connectionless Services • Service Primitives • The Relationship of Services to Protocols

  33. Network SoftwareProtocol Hierarchies • Layers, protocols, and interfaces.

  34. Protocol Hierarchies (2) • The philosopher-translator-secretary architecture.

  35. Protocol Hierarchies (3) • Example information flow supporting virtual communication in layer 5.

  36. Design Issues for the Layers • Addressing • Error Control • Flow Control • Multiplexing • Routing

  37. Connection-Oriented and Connectionless Services • Six different types of service.

  38. Service Primitives • Five service primitives for implementing a simple connection-oriented service.

  39. Service Primitives (2) • Packets sent in a simple client-server interaction on a connection-oriented network.

  40. Services to Protocols Relationship • The relationship between a service and a protocol.

  41. Reference Models with Layers • A layer should have well defined function • Function of a layer should be internatinationally standardized • The information flow between interfaces should be minimized

  42. Reference Models • The OSI reference model • The TCP/IP reference model • Hybrid reference model

  43. Reference Models The OSI reference model.

  44. Reference Models (2) • The TCP/IP reference model.

  45. Reference Models (3) • Protocols and networks in the TCP/IP model initially.

  46. Comparing OSI and TCP/IP Models • Concepts central to the OSI model • Services • Interfaces • Protocols • Concept of TCP/IP • Implementation of the required functionality with three layers

  47. A Critique of the OSI Model and Protocols • Why OSI did not take over the world • Bad timing • Bad technology • Bad implementations • Bad politics

  48. Bad Timing • The apocalypse of the two elephants.

  49. A Critique of the TCP/IP Reference Model • Problems: • Service, interface, and protocol not distinguished • Not a general model • Host-to-network “layer” not really a layer • No mention of physical and data link layers • Minor protocols deeply entrenched, hard to replace

  50. Hybrid Model • The hybrid reference model to be used in this book.

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