1 / 33

Available bandwidth measurement as simple as running wget

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.

lilianna-valerian
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. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

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

More Related