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CMPE 150 – Winter 09

CMPE 150 – Winter 09. Lecture 2 January 8, 2009 P.E. Mantey. CMPE 150 -- Introduction to Computer Networks. Instructor: Patrick Mantey mantey@soe.ucsc.edu http://www.soe.ucsc.edu/~mantey/ Office: Engr. 2 Room 595J Office hours: Tuesday 3-5 PM TA: Anselm Kia akia@soe.ucsc.edu

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CMPE 150 – Winter 09

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  1. CMPE 150 – Winter 09 Lecture 2 January 8, 2009 P.E. Mantey

  2. CMPE 150 -- Introduction to Computer Networks • Instructor: Patrick Mantey mantey@soe.ucsc.edu http://www.soe.ucsc.edu/~mantey/ • Office: Engr. 2 Room 595J • Office hours: Tuesday 3-5 PM • TA: Anselm Kia akia@soe.ucsc.edu • Web site: http://www.soe.ucsc.edu/classes/cmpe150/Winter09/ • Text: Tannenbaum: Computer Networks (4th edition – available in bookstore, etc. )

  3. Syllabus

  4. Assignment #1 Available on the web site: http://www.soe.ucsc.edu/classes/cmpe150/Winter09/ Due Thursday January 15, 2009

  5. Today’s Agenda • “Big Picture”, terminology • Networking Overview (continued) • Protocol Concepts • Network Software • Architecture(s) • History (ARPA Net, NSF Net) • Networks Today: ATM, Ethernet, etc.

  6. Network Hardware • Local Area Networks • Metropolitan Area Networks • Wide Area Networks • Wireless Networks • Home Networks • Internetworks

  7. Classification of Networks by Transmission Technologies • Broadcast • Selection by addressing • Multicast • Point-to-Point • unicast

  8. Classification of interconnected processors by scale

  9. Home Network Categories • Computers (desktop PC, PDA, shared peripherals • Entertainment (TV, DVD, VCR, camera, stereo, MP3) • Telecomm (telephone, cell phone, intercom, fax) • Appliances (furnace, air conditioner, oven, clothes dryer, pool pump, lights, microwave, refigerator..) • Telemetry (utility meter, burglar alarm, babycam).

  10. Local Area Networks • Two broadcast networks • (a) Bus • (b) Ring (e.g. IEEE 802.5)

  11. Metropolitan Area Networks A metropolitan area network based on cable TV -- New alternative is “WiMax” – IEEE 802.16

  12. Wide Area Networks Relation between hosts on LANs and the subnet.

  13. Wide Area Networks (2) A stream of packets from sender to receiver-routers “store and forward” – “packet switching”

  14. Wireless Networks • Categories of wireless networks: • System interconnection • Master/slave • Wireless LANs (e.g. 802.11) • Wireless WANs (e.g. 802.16)

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

  16. Protocols • Used for communications between entities in a system • Must speak the same language • Entities • User applications • e-mail facilities • terminals • Systems • Computer • Terminal • Remote sensor

  17. Layered Architecture • Each layer offers a service • Details of how service is offered in hidden • Each layer talks to the layer immediatley “above” and the layer “below” • “protocol”: communication rules

  18. Key Elements of a Protocol • Syntax • Data formats • Signal levels • Semantics • Control information • Error handling • Timing • Speed matching • Sequencing

  19. Network SoftwareProtocol Hierarchies Layers, protocols, and interfaces.

  20. Protocol Architecture • Task of communication broken up into modules • For example file transfer could use three modules • File transfer application • Communication service module • Network access module

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

  22. Service Primitives Five service primitives for implementing a simple connection-oriented service (Tannenbaum, pg. 35-6)

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

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

  25. Simplified File Transfer Architecture Stallings Chapter 1

  26. A Three Layer Model • Application Layer • Transport Layer • Network Access Layer

  27. Network Access Layer • Exchange of data between the computer and the network • Sending computer provides address of destination • May invoke levels of service • Dependent on type of network used (LAN, packet switched etc.)

  28. Transport Layer • Reliable data exchange • Independent of network being used • Independent of application

  29. Application Layer • Support for different user applications • e.g. e-mail, file transfer

  30. Addressing Requirements • Two levels of addressing required • Each computer needs unique network address • Each application on a (multi-tasking) computer needs a unique address within the computer • The service access point or SAP

  31. Protocol Architectures and Networks Stallings Chapter 1

  32. Protocols in Simplified Architecture Stallings Chapter 1

  33. Protocol Data Units (PDU) • At each layer, protocols are used to communicate • Control information is added to user data at each layer • Transport layer may fragment user data • Each fragment has a transport header added • Destination SAP • Sequence number • Error detection code • This gives a transport protocol data unit

  34. Network PDU • Adds network header • network address for destination computer • Facilities requests

  35. Operation of a Protocol Architecture

  36. TCP/IP Protocol Architecture • Developed by the US Defense Advanced Research Project Agency (DARPA) for its packet switched network (ARPANET) • Used by the global Internet • No official model but a working one.

  37. TCP/IP Reference Model • Application layer • Transport layer (Host-to-host layer) • Internet layer • Host-to-Network layer • Network access layer • Physical layer

  38. Physical Layer • Physical interface between data transmission device (e.g. computer) and transmission medium or network • Characteristics of transmission medium • Signal levels • Multiplexing / demultiplexing • Data rates • etc.

  39. Network Access Layer(Host-to-Network Layer) • Exchange of data between end system and network • Destination address provision • Invoking services like priority

  40. Internet (Network) Layer (IP) • Systems may be attached to different networks • Routing functions across multiple networks • Implemented in end systems and routers

  41. Transport Layer (TCP) • Reliable delivery of data • Ordering of delivery

  42. Application Layer • Support for user applications • e.g. http, SMPT

  43. TCP/IP Protocol Architecture Model Stallings Chapter 1

  44. OSI Model • Open Systems Interconnection • Developed by the International Organization for Standardization (ISO) • Seven layers • A theoretical system delivered too late! • TCP/IP is the de facto standard

  45. OSI Layers • Application • Presentation • Session • Transport • Network • Data Link • Physical

  46. OSI vs TCP/IP (From Stallings, Ch. 1)

  47. Internet Layering Level 5 -- Application Layer (rlogin, ftp, SMTP, POP3, IMAP, HTTP..) Level 4 -- Transport Layer(a.k.a Host-to-Host) (TCP, UDP, ARP, ICMP, etc.) Level 3 -- Network Layer (a.k.a. Internet) (IP) Level 2 -- (Data)Link Layer / MAC sub-layer (a.k.a. Network Interface or Network Access Layer) Level 1 -- Physical Layer

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