NOTES SHEET

NOTES SHEET - Telepho ne networks were engineer edfor speed...

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Trunks Trunk  lines  carry  more  than 1  call Frequen cy  Division  Multiplex ing Time  Division  Multiplex ing Telepho ne  Network  Design Telepho ne  networks  were  engineer ed for  speed Don’t  want lag Internet  Architect ure and  Topolog y Internet  Design The  Internet  was  originally  engineer ed for  data  File  transfer,  email Service  Charact eristics Variable  Bit Rate  (bursty) Connecti on  duration  measure d in  seconds Perform ance Loss  often not  ok  (email) Delay – design  variable Through put-  design  variable Packet  Switchi ng Idea:  Decomp ose  messag e into  packets Transmit  the  packets  one by  one Packet  Switche s/Router replace  telephon e routers Instead  of  setting  up  “circuits”  for each  call,  route  packets  one by  one Packets  are  buffered,  first in  first out. Efficient  for  bursty  traffic Header  [Address ] –  Payload  – Trailer Statistic al  Multiplex ing Same  LAN:  Packets  go into  queue Multiplex ing – two  streams  going  together Internet  current  strucutur e Network  Service  provider  Network  Access  points  Internet  Service  provider s Internet  Applicat ions Email File  Transfer www E- commer ce Gaming Social  networks Streamin g File  Sharing Voice/Vi deo over  Internet Internet  Devices Comput ers,  servers Routers,  Wireless  access  base  stations Links  (twisted  pair  copper,  coax  copper,  fiber, Wi- Fi, 3G) Smart  cell  phones E- readers,  tablets Internet  connect ed  phones,  TVs,  DVRs,  picture  frames,  fridges Internet  network  of  networks Mobile  network  – Global  ISP Home  network  –  Regional  ISP Intuition al  Network  Internet  Protocol s Sloping  down:  Distance  over  Time Perform ance  Metrics Delay Types  of Delay Process ing Data Propag ation  time Queue Transmi ssion:  how fast  I can  throw  bits on  the wire Time  versus  Distance Transmi ssion  Delay Packet  Transmi ssion  Delay  [1 st  Side] Packet  Size/  Transmi ssion  Rate Size of  Packet Measure ments of  Bits per  second Propaga tion  Delay Distance  Propaga tion  Speed Distance Depend s on  Wire  Type Packet =  512 B Hop =  100 km Transmi ssion  rate = 10  MBps 512 * 8 3 x 10^8  m/s Queuing  Delay L:  packet  length  (bits per  packet) A:  average  packet  arrival  rate  (packets  per  second) R: link  bandwidt h (bps =  bits per  second) Average  queuein g delay Traffic  intensity  = La/R  Goes  up but  starts  getting  steeper Multiple  Hops Two  hops to  get to  destinati on First hop  to router,  second  hop to  destinati on Can  send  once u  have  header But  more  common ly, wait til  queue is  finished  and rest  of  packet is  sent WAIT  TIL  queue is  done Types of 
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NOTES SHEET - Telepho ne networks were engineer edfor speed...

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