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Internet measurement (Presentation)

M.Sc. seminar about Internet Measurement
Presentation in English
You can watch the video at: http://www.aparat.com/v/8pcO0

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Internet measurement (Presentation)

  1. 1. Internet Traffic Measurement Amir Hossein Mandegar Dr. B. Akbari September 2011 Computer Engineering and IT Department
  2. 2. Internet Traffic Measurement 2 Outline  Why ?  Tools  Challenges  Applications
  3. 3. Internet Traffic Measurement 3 Why Measure ?  Although Internet works, it is far from being ideal  Measurements of various aspects of it will:  Help us to better understand why it works the way it does  Help us to diagnose known problems and lead us one step closer to their solutions  Help us to design new features that the Internet should provide to enable next-generation application requirements Simply put, “Internet Measurements is key to the design of the next-generation Internet”
  4. 4. Internet Traffic Measurement 4 What to Measure ?  Physical Properties  Devices (routers, NAT boxes, firewalls, switches), Links (wired, wireless)  Topology Properties  Various levels – Autonomous Systems (AS), Points of Presence (PoP), Routers, Interfaces  Traffic Properties  Delays (Transmission, Propagation, Queuing, Processing etc.), Losses, Throughput, Jitter
  5. 5. Internet Traffic Measurement 5 Outline  Why ?  Tools  Challenges  Applications
  6. 6. Internet Traffic Measurement 6 Measurement Tools  Active Measurement  Passive Measurement  Fused/Combined Measurement  Inference Measurement  Others
  7. 7. Internet Traffic Measurement 7 Active Measurement Tools  Methods that involve adding traffic to the network for the purposes of measurement Ping: Sends ICMP ECHO_REQUEST and captures ECHO_REPLY  Useful for measuring RTTs  Only sender needs to be under experiment control Traceroute: Ping nodes with incremental TTL from one  Find Hops between source and destination node  Only sender needs to be under experiment control  There is some care about the result
  8. 8. Internet Traffic Measurement 8 Active Measurement Load  Active Measurement inserts considerable load on network links if attempting a large-scale topology discovery  Optimizations reduce this load considerably  If single source is used, instead of going from source to destination, a better approach is to retrace from destination to source  If multiple sources and multiple destinations are used, sharing information among these would bring download considerably
  9. 9. Internet Traffic Measurement 9 Passive Measurement  Capture traffic generated by other users and applications  Routeview collects BGP views (routing tables) from a large set of ASes  OSPF LSAs can processed to generate router graphs within an AS
  10. 10. Internet Traffic Measurement 10 Fused Measurement  Active Measurement +  Passive Measurement +  Fused Measurement mixed method to use benefits of each method.  Less Traffic Load  Less Required Storage  More information for decision
  11. 11. Internet Traffic Measurement 11 Inference Measurment  Measurement Limitations  Direct access impossible  Topology and link out of reach  How to solve ?  End-to-End Measurement  Tomography: process of inferring network topology, delays, packet losses etc. using only end-to-end measurements
  12. 12. Internet Traffic Measurement 12 Outline  Why ?  Tools  Challenges  Applications
  13. 13. Internet Traffic Measurement 13 Measurement Level  Bit & Bytes (useless)  Packets (High volume)  High volume but valuable data for offline & generate traffic  Flow (limited to flows)  Protocols (Specific Protocol)  TCP, UDP, IP, RTP, ..  Application (Known applications)  HTTP, DNS, MAIL, VOIP, ...  SNMP
  14. 14. Internet Traffic Measurement 14 Hidden Pieces - Middleboxes  Firewalls – provide security  Traffic Shapers – assist in traffic management  Proxies – improve performance  NAT boxes – utilize IP address space efficiently Each of these impedes visibility of network components. Example:  firewalls may block active probing requests  NATs hide away the no. of hosts and the structure of the network on the other side
  15. 15. Internet Traffic Measurement 15 Trace Challenges  Payload Privacy  Encryption  Sanitization  Reduction Techniques (OC-48, 50% utilization, 155MBps)  TCP: Syn/Fin/Rst  Uni-direction Analysis  Sampling Techniques
  16. 16. Internet Traffic Measurement 16 Outline  Why ?  Tools  Challenges  Applications
  17. 17. Internet Traffic Measurement 17 Bandwidth Measurment  Bandwidth Measurement  Amount of data the network can transmit per unit time  Three kinds of bandwidth  capacity: max throughput a link can sustain,  available bandwidth: capacity – used bandwidth  bulk transfer capacity: rate that a new single long-lived TCP connection would obtain over a path
  18. 18. Internet Traffic Measurement 18 Path Provisioning by Traceroute  Suppose the path between A and D is to be determined using traceroute A X Y D B C
  19. 19. Internet Traffic Measurement 19 Traceroute Process A X Y D B C Dest = D TTL = 1 B: “time exceeded”
  20. 20. Internet Traffic Measurement 20 Traceroute Process A X Y D B C Dest = D TTL = 2 C: “time exceeded”
  21. 21. Internet Traffic Measurement 21 Traceroute Process A X Y D B C Dest = D TTL = 3 D: “echo reply”
  22. 22. Internet Traffic Measurement 22 Traceroute issues  Path Asymmetry (Destination -> Source need not retrace Source -> Destination)  Unstable Paths and False Edges  Aliases  Measurement Load
  23. 23. Internet Traffic Measurement 23 Unstable Paths and False Edges Inferred path: A -> B -> Y A X Y D B C Dest = D TTL = 1 B: “time exceeded” Dest = D TTL = 2 Y: “time exceeded”
  24. 24. Internet Traffic Measurement 24 Aliases  IP addresses are for interfaces and not routers  Routers typically have many interfaces, each with its own IP address  IP addresses of all the router interfaces are aliases  Traceroute results require resolution of aliases if they are to be used for topology building
  25. 25. Internet Traffic Measurement 25 Video Quality Measurment  Subjective Evaluation  Variety cause of user experience  Need many user to vote  Objective Evaluation  Data Metrics (PSNR)  Picture Metrics (MPQM ,SSIM)  Packet/Bit stream Metrics (Loss)  Full/Reduced/Non Reference  Visible/Invisible distortion
  26. 26. Internet Traffic Measurement 26 Video Quality Measurment  GOP  Frames (P, I, B)  Slices
  27. 27. Internet Traffic Measurement 27 Video Quality Measurment  Stream should be packetized  TS(DVB) vs RTP(IPTV)  Passive Measurement  Deep Packet Inspection  Resilience and Error correction  Quality Estimation (Fuzzy, NN, ...)
  28. 28. Thank You!

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