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EETS 7304 Internet Protocols

EETS 7304 Internet Protocols

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EETS 7304 Internet Protocols

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  1. byDr. Faruk HadziomerovicTextbook: Andrew Tanenbaum:Computer Networks 4-th Ed.Complementary: Peterson, Davie: Computer networks, 3-rd Ed. EETS 7304 Internet Protocols EETS 7304

  2. Syllabus The course is to introduce students to the concept of Networking. After introduction (uses of computer networks, PSTN, PLMN, Internet, reference models, networks examples, standard bodies) the course goes into details TCP/IP layers implementation: the physical layer (theoretical limits, transmission media, multiplexing, switching, GSM, ADSL vs. cable, fiber vs. satellite), the data link layer (framing, error detection, sliding window, HDLC, verification), the medium access protocol (CSMA/CD, Ethernet, 802.xx, data link layer switching), the network layer (routing algorithms, congestion control, IP addressing and application on Internet, ICMP, IPv6), the transport layer (UDP, TCP, performance issues), the application layer (DNS, e-mail, client/server model, web, multimedia, VoIP), network security (data encryption, public-key algorithms, firewalls, VPNs, authentication protocols). EETS 7304

  3. Admin Office hours: Thursdays 5 to 6:30 PM (Adjunct Room at 3-rd floor Junkins) Verification (open book, no electronic devices): Final 3 hours, 40%, SMU scheduled. Midterm 1.5 hours, 20% mid October. 4 Tests/Assignments, 10% each, every 3 weeks. EETS 7304

  4. Chapter 1: Introduction • Uses of Computer networks • Network Hardware • Network Software • Reference Models • Network Examples • Network Standardization EETS 7304

  5. Business Applications • common data bases (inventories, payrolls). • company e-mail. • video-conferencing (sharing virtual blackboard). • e-business (suppliers and customers ordering parts in a real time). • e-commerce (airlines, bookstores, e-bay shopping). • e-governement (application forms and submittals). EETS 7304

  6. Business Applications: client-server EETS 7304

  7. Client-server communications EETS 7304

  8. Home Applications • access to remote information (surfing the web for: business, government, finance, news, music, digital library like IEEE). • person-to-person: e-mail, messenger, phone with video – SKYPE. • Newsgroups • Interactive entertainment: playing chess. • peer-to-peer (swapping music indicating on Napster server, keeping shared list of available songs on personal computer). EETS 7304

  9. Home Applications: peer-to-peer EETS 7304

  10. Mobile Users • smart phone (Blackberry): PDA (Personal Digital Assistant) combo with cellular phone. • mobile office (while on the move: surf the web, send e-mail). • fleets of (trucks, taxis, delivery vehicles, repairs). • military. • telemetry (parking, vending machines, utility meter reading). • m-commerce use WAP (Wireless Application Protocol). Locality of the shopping, maps, etc. • cheap and popular SMS. EETS 7304

  11. Wireless vs. Mobile examples EETS 7304

  12. Social Issues • censoring (moderating?) newsgroups with sensitive character, politics, religion. • tracking users activities (cookies). • electronic theft. • viruses and security. • Uncle Sam vs. privacy. EETS 7304

  13. Network Hardware • Local Area Networks • Metropolitan Area Networks • Wide Area Networks • Wireless Networks • Home Networks • Internetworks EETS 7304

  14. Classification by types of Physical links Broadcast links: Everybody listens (promiscuous mode). Destination address necessary. • Unicast: “Watson come here. I want you.” Although everybody listens only Watson responds. • Multicast (stations are subscribed to the group): “all passengers flight 234 to report to gate 33 for boarding.” • Broadcast: everybody receives a message. Point-to-point links: equivalent (but not equal) to unicast. • No node in between. No addressing necessary. • Logical point-to-point might have many nodes in between. Point-to-multipoint: HDLC. One address necessary either sender or receiver. EETS 7304

  15. Classification by physical size EETS 7304

  16. Local Area Networks Two broadcast LANs: (a) Bus, (b) Ring • LANs with decentralized (vs. centralized channel allocation) control: IEEE 802.3 = Ethernet (10 Mbps, 100 Mbps, 10 Gbps) • Ring networks: IEEE 802.5 = IBM Token Ring (4 and 16 Mbps), FDDI (Fiber Distributed Data Interface) Gbps. EETS 7304

  17. Metropolitan Area Networks Example of MAN: cable TV. EETS 7304

  18. WAN (Wide Area Networks) = Internet • Data Message is split into PDUs (Packet Data Units have maximum length). • Routers are switching elements for PDUs. They use store and-forward concept. EETS 7304

  19. Store-and-forward concept • Connection-oriented: Virtual Circuits (every packet goes the same route). • Conectionless: routing decisions are made locally at each router -> missequencing. • Source routing: source specifies path (sequence of routers) in a packet header. EETS 7304

  20. History: Network Milestones 1876 Alexander Graham Bell telephone, 1878 exchange 1884 long distance 1901 Marconi ship-to-shore telegraph using Morse code. Before WWI Strawger Switch WWI: Teletype (fax) (start/stop bits predecessor of RS232 for modems) 1924 Henry Nyquist from AT&T Sampling Theorem WWII: Automatic Repeat Request (ARQ) introduced sequence numbering 1948 Claude Shannon from Bell Labs Channel Capacity Theorem 1950s Forward Error Correction (FEC) 1960 Crossbar switch: Ericsson 1960 RS232 physical layer interface standard 1960 Laser enabled fiber optic communication 1960s Digital Electronic Switch with stored program computer (SPC) 1ESS US Bell 1962 T-1 Carrier System (24 DS0s=1.536 Mbps + 8kbps = 1.544 Mbps) developed by AT&T, DS30 in Europe (32 DS0s = 2.48 Mbps) 1963 Geo-stationary satellite was placed 36,000 miles above equator 1968 FCC decision to let any vendor to attach its equipment to telephony network 1964 First commercial computer network for SABRE built by IBM EETS 7304

  21. Network Milestones (2) 1970 ALOHA 1971 ARPANET promoted packet switching 1974 Ethernet (Metcalfe at Xerox) 1974 TCP/IP Cerf and Kahn. 1974 SNA (System Network Architecture) was IBM standard: SDLC (Synchronous Data Link Control) -> ISO HDLC (High Level Data Link Control) -> 1984 CCITT (ITU) LAPD (Link Access Procedure D-channel) 1976 Western Electric 4ESS fully digital voice switch 1983 ARPANET was split to MILNET (160 nodes, 24 in Europe, 11 Pacific rim) and ARPANET for Universities (50 nodes) -> NSFNET 1983 ISO OSI (Open System Interconnect) revised 1995 (7 Layer Standard). 1984 AT&T divestiture caused split into 23 BOCs + AT&T services, Lucent systems & technology. 1984 ISDN (Integrated Services Digital Network) CCITT -> ITU (BRI - Base Rate ISDN: 2B+D, and PRI - Primary Rate ISDN: 23B+D) 1984 SS7 - out of band signaling CCITT -> Intelligent Networks (IN) 1984 X.25 packet switching networks CCITT 1987 was 3.2 million km fiber in USA 1988 US/Britain transatlantic fiber 40,000 conversations EETS 7304

  22. register ringer bell Telephone switching dialer bell Strawger step-by-step concept signaling marker register dialer voice crossbar switch Stage Networks: Benes (recursive approach), Closs 3 stage networks (recursive) Interconnection networks: Shuffle (Stone 1971), Delta (Patel 1976), Omega (Lawrie 1975) etc. EETS 7304

  23. Hardware switching: Interconnection Network (3 stages blocking vs. 5 stages non-blocking) X N=000 N=000 Y 001 001 010 010 011 011 100 100 101 101 110 110 111 111 non-blocking addition blocking Number of switches = (N/2) log2N + (N/2) (log2N - 1) = N log2N - N/2 = 20 vs crossbar 8 * 8 = 64 for N=8 for N=64 => crossbar = 64*64=4096, stage = 32*6 + 32*5 = 352. EETS 7304

  24. Network topologies Point-to-point Bus: Aloha, wireless (radio), Ethernet (coax) Ring: FDDI Point-to-multipoint Star General or mesh Fully connected Gateway EETS 7304

  25. Wireless Networks • Categories of wireless networks: • System interconnection – Bluetooth. • Wireless LANs (WiFi) – 802.11: 50 Mbps/30 ft. • Wireless WANs (telephone cellular networks: GSM, CDMA, UMTS) ~ 2 Mbps. • WiMax (bypassing telephone system) – 802.16: 10 Mbps/10 ml. EETS 7304

  26. Wireless Networks (2) (a) Bluetooth configuration: PC master-slave (mouse, keyboard, etc.) (b) Wireless LAN (WiFi): PC use wireless modems to talk to base station. EETS 7304

  27. Wireless Networks (3) (a) Individual mobile computers (b) A flying LAN EETS 7304

  28. 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, a/c) • Telemetry (utility meter, burglar alarm, babycam). EETS 7304

  29. Network Software • Protocol Hierarchies • Design Issues for the Layers • Connection-Oriented and Connectionless Services • Service Primitives • The Relationship of Services to Protocols EETS 7304

  30. Network Software: Protocol Hierarchies Layers, protocols, and interfaces. Each layer is a kind of virtual machine offering services to the layer above it. EETS 7304

  31. The philosopher-translator-secretary architecture. EETS 7304

  32. Framing and Encapsulation EETS 7304

  33. Design Issues for the Layers • Addressing: network has many computers. An address is needed to specify a specific destination. • Error Control: the way to tell if the message is correct. • Flow Control: fast sender can swamp slow receiver. • Multiplexing: statistical multiplexing at any level. • Routing: either political or technical optimization. • Sequencing: keep the order of received messages. • Dissasembling/reassembling. EETS 7304

  34. Connection-Oriented and Connectionless Services EETS 7304

  35. Services to Protocols Relationship EETS 7304

  36. Interfaces and Service Access Points System A System B peer protocol Layer (N+1) Layer (N+1) interface protocol interface protocol interface service access peer protocol Layer N Layer N Interface: boundary between adjacent layers in the same system. Service Access Point (SAP): is a point where the service is provided by lower layer to higher layer. Interface protocol: operating rules between adjacent layers across the interface. Primitive: messages of interface protocol. EETS 7304

  37. Generic OSI service primitives System A System b Service user layer (N+1) Service provider layer N Service provider layer N Service user layer (N+1) request indication response confirm System A System B connection request connection phase connection ack data (request) data transfer phase data (ack) disconnect request disconnect phase disconnect ack EETS 7304

  38. Five service primitives for implementing a simple connection-oriented service. EETS 7304

  39. Packets sent in a simple client-server interaction on a connection-oriented network. EETS 7304

  40. data query connect request connect ack send send Idle Idle Con- nect request for data listen data disco nnect disco nnect rece ive rece ive disconnect disconnect server client Service primitives vs. protocol messages EETS 7304

  41. Reference Models • The OSI Reference Model • The TCP/IP Reference Model • A Comparison of OSI and TCP/IP • SS7 Reference Model vs. OSI • A Critique of the OSI Model and Protocols • A Critique of the TCP/IP Reference Model EETS 7304

  42. OSI Reference Model EETS 7304

  43. ISO OSI reference model (protocol stack) Application Layer User interface (task-to-task) Data representation, formatting, code conversion Presentation Layer Dialog Control (connection establishment, message exchange) Session Layer Transport Layer Packetizing, end-to-end reliability (error checking, flow control) Network Layer Routing: X.25 Data Link Layer Point-to-point error free: HDLC, LAPD Physical Layer Coding, modulation: AMI, NRZ, Manchester EETS 7304

  44. OSI layer functions Physical layer: provides electrical, functional, and procedural means to activate, maintain, and deactivate physical links that transparently pass the bit stream for communication; only recognizes individual bits (not characters nor frames) and provides bit synchronization; peer-to-peer. Data link layer: provides functional and procedural means to transfer data between network entities and possibly correct transmission errors; provides activation, maintenance and deactivation of data link connection; groups bits into characters and message frames; provides frame synchronization, error control, media access control, and flow control; peer-to-peer. Network layer: provides routing, relaying, and switching functions to establish, maintain, and terminate network layer connections between users. Transport layer: provides transparent transfer of data between systems for upper layers; provides end-to-end control and information interchange with required quality of service. Session layer: provides mechanism for organizing dialogue between application processes; allows full duplex or half-duplex data exchange (finite state machine message exchange). Presentation layer: provides different data presentation (for application layer); provides syntax selection and conversion (encryption) by allowing user to select presentation context. Application layer: provides process parts necessary for communication between processes. EETS 7304

  45. Physical Layer: Baseband PCM waveform types Bits 1 0 1 1 0 0 1 1 0 +V -V NRZ - Non Return to Zero AMI - Alternate Mark Invert Manchester coding +V -V +V -V Requirements: 1. No DC component, 2. Self-clocking, 3. Error detection, 4. Bandwidth compression 5. Noise immunity. EETS 7304

  46. A A A = = = = = = = - = = C ; C C ; C C 0 ; C C ; C C 0 ; - - - - 0 1 1 2 2 3 3 4 4 p p 2 3 Fourier Transform: periodic signals where Example: Pulse train A t T T0 AT/T0 =>> T0/T -5 -4 -3 -2 -1 0 1 2 3 4 5 6 for T0/T=2 => EETS 7304

  47. non-periodic signals Example: unit impulse function d(t) 1/(2d) t -d d EETS 7304

  48. t Delta impulse or =>> white spectrum. 1/2d 1 f -d d 0 white spectrum EETS 7304

  49. TD RTS DTR RD CTS DSR RI RLSD GRND TD RTS DTR RD CTS DSR R RLSD GRND DSR DTR RI RTS CTS CD TD RD DTE DTE DCE DCE Handshaking between two modems in RS-232C PC Modem Data Set Ready DSR DTR RI RTS CTS CD TD RD Data Terminal Ready Ring Indicator Request To Send Clear To Send Carrier Detect Transmit Data Receive Data Modem PC RTS – 0011110 RI - 0000111 DB9 bit connector EETS 7304