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Hardware Building Blocks

Hardware Building Blocks. Chapter 2. Other Items . Comments on the Devotional? Inauguration Family Home Evening Tonight at 7pm Marriot Center Pizza Social Wed, Sep 24 th , pick up tickets Quiz change to unlimited retakes. Objectives. Understand hardware level capabilities

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Hardware Building Blocks

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  1. Hardware Building Blocks Chapter 2

  2. Other Items • Comments on the Devotional? • Inauguration Family Home Evening • Tonight at 7pm Marriot Center • Pizza Social Wed, Sep 24th, pick up tickets • Quiz change to unlimited retakes

  3. Objectives • Understand hardware level capabilities • Know transfer rate limits • Be familiar with key networking terms and rates

  4. Nodes • Assume general-purpose (programmable) computers; • e.g., workstations. Sometimes replaced with special-purpose hardware. • Finite memory (implies limited buffer space) • Connects to network via a network adaptor • Fast processor, slow memory

  5. Architecture CPU Network Cache (T o network) adaptor I/O bus Memory

  6. Frequencies

  7. Links Sometimes you install your own Sometimes leased from the phone company Where did the T1 rate come from? Maximum rate you could send at without repeaters between manholes in Manhattan. STS=Synchronous Transport Signal=OC=Optical carrier

  8. Verizon Federal Market's FCC Tariff – ATM http://www22.verizon.com/federal/it_fcc_tariff.html DS1 (1.544Mbps) - PVC or SVC $600.00 DS3 (45Mbps) -PVC-VBR Service -1st 10 Mbps $3100.00 -Each additional 5Mbps $60.00 -35 Mbps and above (1-9 UNI's)$3400.00 (10-19) -PVC-CBR Service -1st 10 Mbps $3400.00 -Each additional 5Mbps $65.00 -35 Mbps and above (1-9 UNI's)$3725.00 (10-19) OC3c (155Mbps) SONET -PVC-VBR Service -1st 10 Mbps $4200.00 -Each additional 5 Mbps $80.00 -70 Mbps and above (1-9 UNI's)$5160.00 OC12c (622Mbps) Direct Fiber -PVC-VBR Service -1st 155 Mbps $10,300.00 -Each additional 10 Mbps $165.00 -355 Mbps and above $14,100.00 Pricing 2002

  9. Connections to your home

  10. Other Media • Never underestimate the bandwidth of a station wagon full of magnetic tapes • Terrestrial Microwave - comparable to coax • Satellite Microwave • Geosynchronous orbit (22,356 miles) • Latency 300msec • Radio - low bandwidth- cellular radio

  11. Low Earth Orbit Satellites (LEOS) • 100 miles, non-stationary • Traffic is passed between satellites • Access from anywhere on earth. • 40 to 400 satellites • Cellular antenna

  12. Satellite

  13. Satellite

  14. Globalstar handset Uses normal cell phone infrastructure when possible

  15. Globalstar coverage

  16. Specific Examples • Irridium, Low Earth Orbit 780 Km, 66 Satellites, $4.4Billion, 5-8 year lifetime, $2500 handset, 25% Above normal long distance – out of business • Globalstar, LEO 1400Km, 48 Satellites, $2.6Billion, $1195 handset 19.95/month, $1.99/minute

  17. DSL 1.554 – 8.448 Mbps 16 – 640 Kbps Central Subscriber office premises Local loop STS- N VDSL at 12.96 – 55.2 Mbps Central Neighborhood optical Subscriber office network unit premises over fiber over 1000 – 4500 feet of copper

  18. Cable Modems • 40Mbps downstream 20Mbps upstream for each channel • Bandwidth shared by neighborhood.

  19. Shannon’s Law • C=Blog(1+S/N) • C=achievable bandwidth • B=bandwidth range (300 Hz – 3300 Hz = 3000 Hz) • S=average signal power • N=average noise power • Signal to noise ratio S/N typical 1000 • For B=3000Hz, C=30Kbps max given signal to noise ratio to home

  20. Industry Changes • LANS • 10Mbps to 1Gbps - 100 fold increase • WANS • 1.5Mbps (T1) to 1Gbps - 1000 fold increase • Voice traffic increasing 3% per year • Data traffic increasing 20% per year

  21. Optical Properties • critical angle - complete reflection Cladding Optical Fiber Index of refraction for core (I1) = 1.45 Core

  22. Optical Characteristics • Speed of light in fiber • about the same as copper, latency same • 2x108 for fiber, 2.3x108 for copper • speed improvement through bandwidth • Not generally a broadcast media • limitations of media 50-75Tbps • current limitations in digital hardware

  23. Modal Dispersion r1 r2 ray 2 travels a longer distance and arrives after ray 1 resulting in a blurred signal, interference

  24. Fiber types • Multimode • suffers from modal dispersion • plastic core, easy to work with • Singlemode • glass core approximately the wavelength of the light used in transmission • Difficult to work with and install

  25. Speed Specifications • OC-1 = 51.84Mbps • OC-n = n(51.84)Mbps • OC-3C = 155Mbps concatenated into one channel

  26. Encoding

  27. Overview • Problem: Encode the binary data that the source node wants to send to the destination node into the signal that propagates over the media • The media is analog and generally induces errors

  28. Signal Transmission Signalling component Signal Node Adaptor Adaptor Node Bits

  29. Synchronization Tasks • Bit Synchronization (physical layer) • character/word synchronization • frame synchronization (data link layer)

  30. Ethernet Example • Data is sent using a carrier frequency • Ethernet does HDLC style bit stuffing in order to do bit synchronization. • Sentinels are then used to delineate frame boundaries. These patterns cannot occur in normal data.

  31. Data Communication • Asynchronous (RS-232 serial lines) • old and simple • provides bit and character synchronization • optional parity error detection • Synchronous transmission • More efficient for large blocks • bit synchronous with clock transmitted • Character or bit oriented

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