available bandwidth measurement as simple as running wget n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Available bandwidth measurement as simple as running wget PowerPoint Presentation
Download Presentation
Available bandwidth measurement as simple as running wget

Loading in 2 Seconds...

play fullscreen
1 / 33
Pat_Xavi

Available bandwidth measurement as simple as running wget - PowerPoint PPT Presentation

174 Views
Download Presentation
Available bandwidth measurement as simple as running wget
An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Available bandwidth measurement as simple as running wget D. Antoniades, M. Athanatos, A. Papadogiannakis, P. Markatos Institute of Computer Science (ICS), Foundation for Research & Technology Hellas (FORTH) C. Dovrolis College of Computing, Georgia Institute of Technology Passive and Active Measurement Conference (PAM) 2006 Presented by Ryan 10 July 2006

  2. Outline • Introduction • Background • Measurement Methodology • Tool - abget • Validation • Measurement

  3. Introduction • End-to-end available bandwidth • Routing and traffic engineering • QoS management • Overlay network

  4. Introduction • Existing tools and techniques • e.g. pathload, IGI/PTR and Spruce • Requiring access at both ends of the measured path • Based on UDP and ICMP protocols

  5. Introduction • New tool – abget • Requiring access only at the receiving host • The sender can be any TCP-based server • Working with TCP packets • Similar estimation methodology to pathload

  6. Background • The term “available bandwidth” • Several definitions • Link capacity • Residual bandwidth • Achievable bandwidth

  7. Background • Link capacity • Maximum data rate a flow that can utilize when there are no other traffic flows sharing the link • End-to-end capacity, C • C = min{C1,C2,…CN} • Ci is the capacity of link i

  8. Background • Residual bandwidth • Unutilized capacity of a path • End-to-end available bandwidth, U • . • where is the unutilized capacity, Ci is the capacity and ui(t, t +τ) is the average link utilization (in normalized unit from 0 to 1) in the interval [t, t +τ) of the link i • Adopted in this paper (and pathload)

  9. Background • Achievable bandwidth • Throughput achievable by a TCP (or TCP-friendly) flow in passing through a network path • End-to-end achievable bandwidth, A • . • di(t,t+τ) – the amount of data received in the interval [t, t+τ) by the receiver from sender i • Adopted in our research work (many-to-one data flow analysis)

  10. Background • pathload – the basic idea • Self-Loading Periodic Streams (SLoPS) • A periodic stream consists of K packets sent to the path at a constant rate R • If R > A (available bandwidth), the one-way delay (OWD) of successive packets at the receiver show an increasing trend M. Jain and C. Dovrolis, “End-to-End Available Bandwidth: Measurement Methodology, Dynamics, and Relation with TCP Throughput,” IEEE/ACM Transactions on Networking, 11(4):537-549, Aug. 2003.

  11. if X holds otherwise Background • Detection of an increasing OWD trend • Partition measured (relative) OWDs = D1, D2,…,DK into Г= groups of Г consecutive OWDs • Compute the median OWD of each group • More robust to outliers and errors • Pairwise Comparison Test (PCT) • , • An increasing trend if SPCT > 0.55

  12. Measurement Methodology • Iterative algorithm similar to SLoPS in pathload • pathload – the sender transmits periodic UDP packet streams at a certain rate • abget – TCP-based server sends packets based on TCP’s flow control and congestion control • How to send packet streams at a certain rate?

  13. Measurement Methodology • The basic idea • A limited advertised window, “fake” ACKs • Receiver – acknowledges only one MMS with each ACK and advertises a window of only one MSS • Sender – is forced to send one MMS upon receiving each ACK

  14. Measurement Methodology • To achieve a certain rate R, the “fake” ACKs should be generated periodically with a period T = MSS/R • Assumption: ACKs arrived at the sender periodically

  15. Measurement Methodology • Validation

  16. Measurement Methodology • One-Way Delay (OWD) • Estimate from the interarrivals of the received packets • s(i) – the time that the sender transmitted the ith packet • r(i) – the time that the receiver got the ith packet • o – the clock offset between the two hosts • t(i) – the interarrival time between packets i and i-1 at the receiver • d(i) – the OWD of packet i • T – the (assumed) constant interarrival time between packets i and i-1 at the sender

  17. Measurement Methodology • OWD Estimation • s(i) = s(i-1) + T • r(i) = s(i) + d(i) + o • t(i) = r(i) – r(i-1) •  d(i) = r(i) – s(i) – o • = d(i-1) + t(i) - T

  18. Tool – abget • abget, using an iterative algorithm • User specifies • Probing range, [Rmin, Rmax] • Estimation resolution, w • Stream length parameter, K • Number of streams per probing rate, N • Probing starts at rate Rmin, gradually increasing the rate in increments of w until Rmax

  19. Tool – abget • In each iteration • Connect to the remote server (web server) and initiates a download operation • Start sending K “fake” ACKs (with a period corresponds to the desired probing rate) • Estimate the OWDs and compute the SPCT (same as pathload) • Repeat the previous process N times

  20. Tool – abget • If more than N/2 of the streams are increasing (non-increasing), the corresponding probing rate is higher (lower) than the available bandwidth

  21. Tool – abget • abget reports a variation range [low_bound, high_bound] • Low_bound – max probing rate that was estimated as lower than the available bandwidth • High_bound – min probing rate that was estimated as higher than the available bandwidth

  22. Validation • Parameters Setting • N = 5 • K = 50 • w = 5Mbps • Rmin = 0Mbps • Rmax = 100Mbps • Ti = 500ms • Measurement Duration ~ 50s

  23. abget Client Web Server Cross Traffic Source Cross Traffic Sink Capacity ~ 97Mbps Validation • In local testbed • Cross Traffic • Constant-rate UDP traffic • Realistic traffic trace

  24. Validation Constant rate UDP traffic Realistic traffic trace

  25. Validation • In the monitored network path

  26. Validation From www.nytimes.com to UoC client From UoC server to Georgia Tech client

  27. Validation • Robustness to reverse path traffic • Forward path – LD ~ 1500B • Reverse path – LA ~ 40B • The ratio LD/LA ~ 40 • Few paths have such a high degree of available bandwidth asymmetry?

  28. Measurement • Measurement in the Internet • Client hosts • The University of Crete (UoC), Greece • The Georgia Institute of Technology, USA • Web servers • www.nero.com (in Germany) • www.chez.com (in France) • Measurement is performed every 10 minutes during a 24-hour period

  29. Measurement

  30. Conclusion • Available bandwidth measurement tool – abget • Single-end • TCP • Similar to Pathload • Validations and Measurements in different network paths

  31. Duration and Overhead • Trade-offs between measurement duration, overhead and accuracy • Parameters • K – stream length • N – number of streams • w – estimation resolution • Ti – idle time between streams • [Rmin, Rmax] – probing range

  32. Duration and Overhead • Measurement Duration • Measurement Overhead (in term of rate) idle time between streams No. of streams per each probing rate No. of probing rate K packets transmission time