NETWORKS• Covering  – High speed switching fabrics  – Twisted pair  – Mediums  – Fiber optics  – Radio  – Ethernet Coax
NETWORKS– Logarithms– Channel capacity– Hartley-Shannon Law– Review of the Layers– Things you need to get started on a LAN
High Speed Switching       Fabrics• Aside from the Bus topologies,  there are many others, with higher  throughput, like• ...
The Transputer  Topology4 way connectivity
The Torus Topology  4 way connectivity
Torus Topology 5 way connectivity
Cray T3D, Torus   Topology 6 way connectivity
Diagram of a typical packet radio setup                           TNCMac          ASYNC             SYNC              Mode...
Twisted Pair• Typically a balanced digital line• 2 conductor insulated wire• Twisting the wire minimizes the  electromagne...
Twisted Pair• The repeat coil (transformer) or  Op-Amp can be used               S+I   S                      +   S+I-(-S+...
Twisted Pair• In telephone modem terms this is  known as a DAA (Data Access  Arrangement).
Mediums• UTP (unshielded twisted pair)  – typical voice line  – Generally good for star LAN short haul 10    Mbps• STP (sh...
Mediums• Coax  – CATV (community antenna TV)  – telephone long line via FDM carries 10,000    voices  – LAN-WAN  – cable TV
Mediums• Fiber Optics  – use total internal reflection  – This occurs in a transparent medium    whose index of refraction...
Fiber Optics• multimode  – different rays have different path lengths,    loss occurs• multimode-graded index  – variable ...
Fiber Optics• LED (light emmiting diode)  – inexpensive• ILD (injection laser diode )  – more expensive (more efficient an...
Fiber Optics• light propagates best at 850, 1300  and 1500 nm• 640 nm = wavelength of HE-NE  red = .64 micro meters• ultra...
Fiber Optics– bandwidth - 2 Gbps (typical)– smaller size and weight than copper– lower attenuation than coax– electromagne...
Radio      • Microwave         – line-of-sight         – parabolic dishd = 7.14 kh = distance to horizond in metersh = hei...
Ethernet Coax• For Ethernet coax  – ASIC’s which give a digital interface to a    bus topology LAN  – For example, the Cry...
Ethernet Coax             CS83C92                   TX-             GND   TX+             TXO   CD-             CDS   CD+ ...
Ethernet Coax• CS83C92  – Balanced serial inputs  – Uses Manchester codes  – All operations with IEEE 802.3 of the    10Ba...
Ethernet Coax• CS83C92 have  – equalizers  – amplifiers  – idle detectors, receiver squelch circuits  – collision testers ...
Logarithms• Log Review       if x = a y then y = log a x       so       if x = 210 then 10 = log 2 x
Logarithms• For example       find log 2 4096               4096 = 2 y               ln 4096 = y ln 2                ln 40...
Logarithmsso          ln xlog 2 x =          ln 2if base = B then          ln x log10 xlog B x =     =          ln B log10 B
Logarithms• Laws of Logarithms        log a (xy) = log a x + log a y        log a (x / y) = log a x − log a y        log a...
• Intermodulation noise  – results when signals at different    frequencies share the same transmission    medium
• the effect is to create harmonic  interface at          f 1 + f 2 and / or f 1 − f 2          f 1 = frequency of signal ...
• cause  – transmitter, receiver of intervening    transmission system nonlinearity
• Crosstalk  – an unwanted coupling between signal    paths. i.e hearing another conversation on    the phone• Cause  – el...
• Impluse noise  – spikes, irregular pulses• Cause  – lightning can severely alter data
Channel Capacity• Channel Capacity  – transmission data rate of a channel (bps)• Bandwidth  – bandwidth of the transmitted...
Channel Capacity• if channel is noise free and of  bandwidth W, then maximum rate  of signal transmission is 2W• This is d...
Channel Capacity• Example   w=3100 Hz   C=capacity of the channel   c=2W=6200 bps (for binary transmission) C = 2Wlog 2 m ...
Channel Capacity• doubling bandwidth doubles the  data rate      if m=8      c = 2(3100 hz)log 2 8 = 18, 600 bps
Channel Capacity• doubling the number of bits per  symbol also doubles the data rate  (assuming an error free channel)   (...
Hartley-Shannon Law• Due to information theory  developed by C.E. Shannon (1948)  C:- max channel capacity in bits/second ...
Hartley-Shannon Law• Example   W=3,100 Hz for voice grade telco lines   S/N = 30 dB (typically)                   Ps 30 dB...
Hartley-Shannon Law            Ps    3 = log            Pn             Ps    log10       =3             Pn             Ps ...
Hartley-Shannon Law• Represents the theoretical  maximum that can be achieved• They assume that we have AWGN  on a channel
Hartley-Shannon Law     C/W = efficiency of channel utilization            bps/Hz     Let R= bit rate of transmission     ...
Hartley-Shannon Law  S = signal power (watts)T b = the time required to send a bit    1R=   TbEb = ST bEb   = energy per n...
Hartley-Shannon LawEb S / R    S   =     =N0   N0    kTR k=boltzman’s constantbyEb = ST b   EbS=    ∴S / R = Eb   TbN0 = kTR
Hartley-Shannon Law assuming R=W=bandwidth in Hz In Decibel Notation:Eb   = S −10 log R + 228. 6dbW − 10 logTN0
Hartley-Shannon LawS=signal power  R= transmission rate and -10logk=228.6  So, bit rate error (BER) for digital data      ...
Hartley-Shannon Law• Example For binary phase-shift keying Eb      =8.4 dB is needed for a bit error rate N0      of 10 −4...
Hartley-Shannon Law• Find S        Eb −S = −    −10 log R + 228. 6dbW − 10log T        N0 −S = −8. 4 − 10 log2400 + 228.6d...
ADC’s• typically are related at a  convention rate, the number of  bits (n) and an accuracy (+- flsb)• for example  – an 8...
ADC’s• The SNR in (dB) is therefore                                    S             SNRdB = 10 log10                     ...
Review of the Layers•   Physical Layer (bits)•   The Link Layer (frames)•   The Network Layer (packets)•   The Transport L...
Physical Layer• The function is to send & receive  bits (marks & spaces)• deals with  – Physical connections (duplex or ha...
Physical Layer– circuit identification– bit sequencing– notification of false conditions– deriving quality of service para...
Physical Layer– transmission of data and handshaking  signals– characterization of communication media– maintains an actua...
The Link Layer• The Link Layer of data link control  arranges the bits into frames• Most common protocol is ISO  high-leve...
The Link Layer• This layer  – Establishes and releases one or more link    connections  – exchanges data-link service data...
The Link Layer– notifies the network layer when errors are  detected– controls data flow– selects optional qualityof servi...
The Network Layer• Arranges data into packets  – Adds the network information to the    frames to form packets• SLIP  – Se...
The Network Layer– keep track of the network node address  while routing outgoing packets and  recognizing packets that ar...
The Network Layer• ARP – Address Resolution Protocol provides   addresses form required by IP – User may specify the datag...
The Network Layer•in CCITT x.25 protocol the network layer is called the packet layer.
The Network Layer• The function provided by the  network layer are  – network addressing and identifiers  – network connec...
The Network Layer– notifies the transport layer of errors– flow control– expedited service network– may provide sequenced ...
The Network Layer• Two types of network layer  protocols  – connection oriented  – connectionless
Connection Protocol• set up a virtual circuit (VC)  between two end points• Advantage is that since each  packet does not ...
Connectionless         Protocol• Uses a datagram (DG) which  contains complete addressing  information in each packet so t...
Connectionless         Protocol• The advantage is that packets  may freely choose the best  available routes for the trans...
The Transport Layer• uses transport protocol data units  (TPDU)• TPDU = packets + transport layer  data• TCP = transmissio...
The Transport Layer• This layer ensures that  – all data send is received completely  – is sequenced  – transmission of TP...
The Transport Layer– error detection– error recovery– connection establishment– data xfer– release of connections
The Transport Layer• CCITT transport protocol in X.224  says there are 5 classes of  transport classes  – 0. simple class ...
The Transport Layer• The amount of work done is  dependent on the protocol (VC or  datagram) used at the network  layer
The Transport Layer• Datagrams may arrive out of  sequence, in a connectionless  net, and buffers may be needed to  resequ...
Session Layer• Organizes data into SPDU  (session protocol data units)
Session Layer• This layer does  – dialog management  – Data flow control  – mapping address with name (domain name    serv...
Session Layer• has phases of service  – connection establishment  – data xfer  – connection release
Presentation Layer• responsible for the terminal  management• Performs  – transfer of syntax for character sets, text    s...
Presentation Layer– data encoding, decoding and compacting– interpret character sets ( i.e. ASCII)– code conversion
Application Layer• The only layer which does not  interface with a higher one• It does  – log in identification of communi...
Application Layer– determine adequacy of resources– determine acceptable quality of service– synchronization of applicatio...
Application Layer• has 5 groups  – 1. System management protocols  – 2. Application management protocols  – 3. System prot...
Things you need to get   started on a LAN• IP ADDRESS – this a 32 bit number issued by your local IP   coordinator – it is...
Things you need to get   started on a LAN• HOST TABLE – A file that list all the folks around you that   also have IP addr...
Things you need to get   started on a LAN• HOST TABLE – you can get this from your coordinator – It looks like this     44...
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Logsv2

  1. 1. NETWORKS• Covering – High speed switching fabrics – Twisted pair – Mediums – Fiber optics – Radio – Ethernet Coax
  2. 2. NETWORKS– Logarithms– Channel capacity– Hartley-Shannon Law– Review of the Layers– Things you need to get started on a LAN
  3. 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. 4. The Transputer Topology4 way connectivity
  5. 5. The Torus Topology 4 way connectivity
  6. 6. Torus Topology 5 way connectivity
  7. 7. Cray T3D, Torus Topology 6 way connectivity
  8. 8. Diagram of a typical packet radio setup TNCMac ASYNC SYNC Modem Radio Serial Serial CPU Memory We left out the redundant curcuitry in the gray box to make poor mans packet
  9. 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. 10. Twisted Pair• The repeat coil (transformer) or Op-Amp can be used S+I S + S+I-(-S+I)=2S - -S -S+I I
  11. 11. Twisted Pair• In telephone modem terms this is known as a DAA (Data Access Arrangement).
  12. 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. 13. Mediums• Coax – CATV (community antenna TV) – telephone long line via FDM carries 10,000 voices – LAN-WAN – cable TV
  14. 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. 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. 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. 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. 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. core, one or more strands cladding, one for each fiber Jacket
  19. 19. Radio • Microwave – line-of-sight – parabolic dishd = 7.14 kh = distance to horizond in metersh = height of antenna in metersk = adjustment factor, microwaves bend with the curature of the earth
  20. 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. 21. Ethernet Coax CS83C92 TX- GND TX+ TXO CD- CDS CD+ RXI RX- RX+ Shi el d
  22. 22. Ethernet Coax• CS83C92 – Balanced serial inputs – Uses Manchester codes – All operations with IEEE 802.3 of the 10Base5 (Ethernet) and 10Base2 (Cheapernet) standard
  23. 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. 24. Logarithms• Log Review if x = a y then y = log a x so if x = 210 then 10 = log 2 x
  25. 25. Logarithms• For example find log 2 4096 4096 = 2 y ln 4096 = y ln 2 ln 4096 = y = 12 ln 2
  26. 26. Logarithmsso ln xlog 2 x = ln 2if base = B then ln x log10 xlog B x = = ln B log10 B
  27. 27. Logarithms• Laws of Logarithms log a (xy) = log a x + log a y log a (x / y) = log a x − log a y log a x n = n log a x
  28. 28. • Intermodulation noise – results when signals at different frequencies share the same transmission medium
  29. 29. • the effect is to create harmonic interface at f 1 + f 2 and / or f 1 − f 2 f 1 = frequency of signal 1 f 2 = frequency of signal 2
  30. 30. • cause – transmitter, receiver of intervening transmission system nonlinearity
  31. 31. • Crosstalk – an unwanted coupling between signal paths. i.e hearing another conversation on the phone• Cause – electrical coupling
  32. 32. • Impluse noise – spikes, irregular pulses• Cause – lightning can severely alter data
  33. 33. Channel Capacity• 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. 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. 35. Channel Capacity• Example w=3100 Hz C=capacity of the channel c=2W=6200 bps (for binary transmission) C = 2Wlog 2 m m = # of discrete symbols
  36. 36. Channel Capacity• doubling bandwidth doubles the data rate if m=8 c = 2(3100 hz)log 2 8 = 18, 600 bps
  37. 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 signal power (S / N)dB = 10log noise power
  38. 38. Hartley-Shannon Law• Due to information theory developed by C.E. Shannon (1948) C:- max channel capacity in bits/second S C = w log2 (1 + ) N w:= channel bandwidth in Hz
  39. 39. Hartley-Shannon Law• Example W=3,100 Hz for voice grade telco lines S/N = 30 dB (typically) Ps 30 dB = 10 log Pn
  40. 40. Hartley-Shannon Law Ps 3 = log Pn Ps log10 =3 Pn Ps 10 3 = = 1000 Pn C = 3100 log 2 (1 + 1000) = 30,898 bps
  41. 41. Hartley-Shannon Law• Represents the theoretical maximum that can be achieved• They assume that we have AWGN on a channel
  42. 42. Hartley-Shannon Law C/W = efficiency of channel utilization bps/Hz Let R= bit rate of transmission 1 watt = 1 J / secEb =enengy per bit in a signal
  43. 43. Hartley-Shannon Law S = signal power (watts)T b = the time required to send a bit 1R= TbEb = ST bEb = energy per noise power density per hertzN0
  44. 44. Hartley-Shannon LawEb S / R S = =N0 N0 kTR k=boltzman’s constantbyEb = ST b EbS= ∴S / R = Eb TbN0 = kTR
  45. 45. Hartley-Shannon Law assuming R=W=bandwidth in Hz In Decibel Notation:Eb = S −10 log R + 228. 6dbW − 10 logTN0
  46. 46. Hartley-Shannon LawS=signal power R= transmission rate and -10logk=228.6 So, bit rate error (BER) for digital data Eb is a decreasing function of N0 Eb For a given N0 , S must increase if R increases
  47. 47. Hartley-Shannon Law• Example For binary phase-shift keying Eb =8.4 dB is needed for a bit error rate N0 of 10 −4 let T= k = noise temperature = C, R=2400 bps & Pe = 10 −4 = BER
  48. 48. Hartley-Shannon Law• Find S Eb −S = − −10 log R + 228. 6dbW − 10log T N0 −S = −8. 4 − 10 log2400 + 228.6dbW −10 log 290 S=-161.8 dbw
  49. 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. 50. ADC’s• The SNR in (dB) is therefore S SNRdB = 10 log10 N where S = 2n 1 −n −n −1 N = 2 =2 2 2n+1 SNRdB = 10 log10 2 = (20n +10)log10 2 about SNRdB = 6n + 3
  51. 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. 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. 53. Physical Layer– circuit identification– bit sequencing– notification of false conditions– deriving quality of service parameters– modulation and demodulation– signaling speed
  54. 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. 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. 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. 57. The Link Layer– notifies the network layer when errors are detected– controls data flow– selects optional qualityof service parameters
  58. 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. 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. 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. 61. The Network Layer•in CCITT x.25 protocol the network layer is called the packet layer.
  62. 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. 63. The Network Layer– notifies the transport layer of errors– flow control– expedited service network– may provide sequenced delivery
  64. 64. The Network Layer• Two types of network layer protocols – connection oriented – connectionless
  65. 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. 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. 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. 68. The Transport Layer• uses transport protocol data units (TPDU)• TPDU = packets + transport layer data• TCP = transmission control protocol
  69. 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. 70. The Transport Layer– error detection– error recovery– connection establishment– data xfer– release of connections
  71. 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. 72. The Transport Layer• The amount of work done is dependent on the protocol (VC or datagram) used at the network layer
  73. 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. 74. Session Layer• Organizes data into SPDU (session protocol data units)
  75. 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. 76. Session Layer• has phases of service – connection establishment – data xfer – connection release
  77. 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. 78. Presentation Layer– data encoding, decoding and compacting– interpret character sets ( i.e. ASCII)– code conversion
  79. 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. 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. 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. 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. 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. 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

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