1. NETWORKS Covering –High speed switching fabrics –Twisted pair –Mediums –Fiber optics –Radio –Ethernet Coax

2. NETWORKS –Logarithms –Channel capacity –Hartley-Shannon Law –Review of the Layers –Things you need to get started on a LAN

3. High Speed Switching Fabrics Aside from the Bus topologies, there are many others, with higher throughput, like ring Transputer Topology Torus Topology Cray T3D

4. The Transputer Topology 4 way connectivity

5. The Torus Topology 4 way connectivity

6. Torus Topology 5 way connectivity

7. Cray T3D, Torus Topology 6 way connectivity

9. Twisted Pair Typically a balanced digital line 2 conductor insulated wire Twisting the wire minimizes the electromagnetic interference A primary medium for voice traffic used as serial cable to hookup networks

10. Twisted Pair The repeat coil (transformer) or Op-Amp can be used

11. Twisted Pair In telephone modem terms this is known as a DAA (Data Access Arrangement).

12. Mediums UTP (unshielded twisted pair) –typical voice line –Generally good for star LAN short haul 10 Mbps STP (shielded twisted pair) –level 5 data grade (100 Mbps) RS-422 –balanced serial data communications RS-232 –unbalanced serial data communications

13. Mediums Coax –CATV (community antenna TV) –telephone long line via FDM carries 10,000 voices –LAN-WAN –cable TV

14. Mediums Fiber Optics –use total internal reflection –This occurs in a transparent medium whose index of refraction is higher that surrounding medium –optic fiber is a wave guide in the 10 raised 14 to 10 raised 15 hz range

15. Fiber Optics multimode –different rays have different path lengths, loss occurs multimode-graded index –variable core index, focuses rays more efficiently that multimode single mode –only the axial ray passes, most efficient.

16. Fiber Optics LED (light emmiting diode) –inexpensive ILD (injection laser diode ) –more expensive (more efficient and higher bandwidth that LED). Detectors –Photo Diodes

17. Fiber Optics light propagates best at 850, 1300 and 1500 nm 640 nm = wavelength of HE-NE red =.64 micro meters ultra pure fused silica is best, plastic is cheapest and worst

18. Fiber Optics –bandwidth - 2 Gbps (typical) –smaller size and weight than copper –lower attenuation than coax –electromagnetically isolated –greater repeater spacing, 5 Gbs over 111 km w/o repeater –phasing out cable.

19. Radio Microwave –line-of-sight –parabolic dish

20. Ethernet Coax For Ethernet coax –ASIC’s which give a digital interface to a bus topology LAN – For example, the Crystal Semiconductor Corporation CS83C92 is a Coaxial Transceiver Interface on a chip

21. Ethernet Coax

22. CS83C92 –Balanced serial inputs –Uses Manchester codes –All operations with IEEE 802.3 of the 10Base5 (Ethernet) and 10Base2 (Cheapernet) standard

23. Ethernet Coax CS83C92 have –equalizers –amplifiers –idle detectors, receiver squelch circuits –collision testers –oscillators –differential line drivers –(with other stuff too!!!) A manchester code convert chip is also needed

24. Logarithms Log Review

25. Logarithms For example

26. Logarithms

27. Laws of Logarithms

28. Intermodulation noise –results when signals at different frequencies share the same transmission medium

29. the effect is to create harmonic interface at

30. cause –transmitter, receiver of intervening transmission system nonlinearity

31. Crosstalk –an unwanted coupling between signal paths. i.e hearing another conversation on the phone Cause –electrical coupling

32. Impluse noise –spikes, irregular pulses Cause –lightning can severely alter data

33. Channel Capacity –transmission data rate of a channel (bps) Bandwidth –bandwidth of the transmitted signal (Hz) Noise –average noise over the channel Error rate –symbol alteration rate. i.e. 1-> 0

34. Channel Capacity if channel is noise free and of bandwidth W, then maximum rate of signal transmission is 2W This is due to intersymbol interface

35. Channel Capacity Example w=3100 Hz C=capacity of the channel c=2W=6200 bps (for binary transmission) m = # of discrete symbols

36. Channel Capacity doubling bandwidth doubles the data rate if m=8

37. Channel Capacity doubling the number of bits per symbol also doubles the data rate (assuming an error free channel) (S/N):-signal to noise ratio

38. Hartley-Shannon Law Due to information theory developed by C.E. Shannon (1948) C:- max channel capacity in bits/second w:= channel bandwidth in Hz

39. Hartley-Shannon Law Example W=3,100 Hz for voice grade telco lines S/N = 30 dB (typically) 30 dB =

40. Hartley-Shannon Law

41. Represents the theoretical maximum that can be achieved They assume that we have AWGN on a channel

42. Hartley-Shannon Law C/W = efficiency of channel utilization bps/Hz Let R= bit rate of transmission 1 watt = 1 J / sec =enengy per bit in a signal

43. Hartley-Shannon Law S = signal power (watts)

44. Hartley-Shannon Law k=boltzman’s constant

45. Hartley-Shannon Law assuming R=W=bandwidth in Hz In Decibel Notation:

46. Hartley-Shannon Law S=signal power R= transmission rate and -10logk=228.6 So, bit rate error (BER) for digital data is a decreasing function of For a given, S must increase if R increases

47. Hartley-Shannon Law Example For binary phase-shift keying =8.4 dB is needed for a bit error rate of let T= k = noise temperature = C, R=2400 bps &

48. Hartley-Shannon Law Find S S=-161.8 dbw

49. ADC’s typically are related at a convention rate, the number of bits (n) and an accuracy (+- flsb) for example –an 8 bit adc may be related to +- 1/2 lsb In general an n bit ADC is related to +- 1/2 lsb

50. ADC’s The SNR in (dB) is therefore where about

51. Review of the Layers Physical Layer (bits) The Link Layer (frames) The Network Layer (packets) The Transport Layer Session Layer The Presentation Layer The Application Layer

52. Physical Layer The function is to send & receive bits (marks & spaces) deals with –Physical connections (duplex or half duplex) –Physical service data units (PSDU’s) one bit in serial xmission, nbits in parallel xmission

53. Physical Layer –circuit identification –bit sequencing –notification of false conditions –deriving quality of service parameters –modulation and demodulation –signaling speed

54. Physical Layer –transmission of data and handshaking signals –characterization of communication media –maintains an actual electrical connection with its peers. Other layers uses virtual connections

55. The Link Layer The Link Layer of data link control arranges the bits into frames Most common protocol is ISO high-level Data Link Control Procedures (ISO 3309)

56. The Link Layer This layer –Establishes and releases one or more link connections –exchanges data-link service data units (DLSDUs)-frames –identifies end-points –keeps DLSDUs / frames in proper sequence

57. The Link Layer –notifies the network layer when errors are detected –controls data flow –selects optional qualityof service parameters

58. The Network Layer Arranges data into packets –Adds the network information to the frames to form packets SLIP –Serial Line Internet Protocol is network layer protocol –uses the EIA-232 Physical layer –Internet protocol is a network layer protocol

59. The Network Layer –keep track of the network node address while routing outgoing packets and recognizing packets that are intended for the local node

60. The Network Layer ARP –Address Resolution Protocol provides addresses form required by IP –User may specify the datagram route –APR will stay aware of manually generated routing tables for the datagram routing function

61. The Network Layer in CCITT x.25 protocol the network layer is called the packet layer.

62. The Network Layer The function provided by the network layer are –network addressing and identifiers –network connections and release –transmission of network service data units NSDU’s (packets) –quality of service parameters

63. The Network Layer –notifies the transport layer of errors –flow control –expedited service network –may provide sequenced delivery

64. The Network Layer Two types of network layer protocols –connection oriented –connectionless

65. Connection Protocol set up a virtual circuit (VC) between two end points Advantage is that since each packet does not contain complete addressing information, the overhead is lower

66. Connectionless Protocol Uses a datagram (DG) which contains complete addressing information in each packet so that it can use any variable route through the network

67. Connectionless Protocol The advantage is that packets may freely choose the best available routes for the transfer rather than being stuck on a VC with variable quality

68. The Transport Layer uses transport protocol data units (TPDU) TPDU = packets + transport layer data TCP = transmission control protocol

69. The Transport Layer This layer ensures that –all data send is received completely –is sequenced –transmission of TPDU messages –multiplexing and demultiplexing to share a net connection between two or more Xport connections

70. The Transport Layer –error detection –error recovery –connection establishment –data xfer –release of connections

71. The Transport Layer CCITT transport protocol in X.224 says there are 5 classes of transport classes –0. simple class –1. error recovery –2. multiplexing –3. error recovery and multiplexing –4. error detection and recovery class

72. The Transport Layer The amount of work done is dependent on the protocol (VC or datagram) used at the network layer

73. The Transport Layer Datagrams may arrive out of sequence, in a connectionless net, and buffers may be needed to resequence connection nets allow a leaner transport layer

74. Session Layer Organizes data into SPDU (session protocol data units)

75. Session Layer This layer does –dialog management –Data flow control –mapping address with name (domain name service) –graceful or abrupt disconnection –buffering data until delivery time

76. Session Layer has phases of service –connection establishment –data xfer –connection release

77. Presentation Layer responsible for the terminal management Performs –transfer of syntax for character sets, text strings data display format, graphics file organization and data types

78. Presentation Layer –data encoding, decoding and compacting –interpret character sets ( i.e. ASCII) –code conversion

79. Application Layer The only layer which does not interface with a higher one It does –log in identification of communication partners –password checking and authority to communicate

80. Application Layer –determine adequacy of resources –determine acceptable quality of service –synchronization of application programs –selecting the dialog procedures –agreement on error-recovery responsibility –procedures for control of data integrity –identifying data syntax constraints

81. Application Layer has 5 groups –1. System management protocols –2. Application management protocols –3. System protocols –4. Industry specific protocols –5. Enterprise protocols

82. Things you need to get started on a LAN IP ADDRESS –this a 32 bit number issued by your local IP coordinator –it is expressed as 4 numbers separated by periods –looks like 44.112.0.200.

83. Things you need to get started on a LAN HOST TABLE –A file that list all the folks around you that also have IP addresses –It must have your IP address and hostname (call sign) at least

84. Things you need to get started on a LAN HOST TABLE –you can get this from your coordinator –It looks like this 44.112.0.1 unix.n3cv1 44.112.0.2 w3vc 44.112.0.3 darth.wa3yoa