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TraceQoS

10th TF-NGN meeting, Rome, February 6th-7th 2003. TraceQoS. A tool for locating QoS failures on an Internet path. Chris Welti, Network Engineer, SWITCH. Outline. Introduction What is TraceQoS? Demonstration Implementation System requirements. Introduction.

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TraceQoS

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  1. 10th TF-NGN meeting, Rome, February 6th-7th 2003 TraceQoS A tool for locating QoS failures on an Internet path Chris Welti, Network Engineer, SWITCH

  2. Outline • Introduction • What is TraceQoS? • Demonstration • Implementation • System requirements

  3. Introduction • Use of Internet for transfer of real-time processed data (e.g. video streams) • Depend on certain QoS of underlying network (e.g. max. dv) • Difficult to locate end-2-end QoS performance problems in IP networks • Crossing management domains • Network operators claim their networks work flawlessly • No common tool for measuring one-way metrics segment by segment over an end-2-end path

  4. What Is TraceQoS? • Active one-way measurement system for locating QoS „failures“ on an IP path from source to destination • On demand tests • TraceQoS measures OWD, OWDV, OWPL segment by segment over end-2-end path • Concurrent measurements on the subpaths • Dynamically displays results while test is in progress • -> Helps to locate segments on the investigated path where QoS performance is not sufficient

  5. A Sample TraceQoS Scenario LEGEND: TS = TraceQoS server rts = link from router to TS tsr = link from TS to router mp = measurement path

  6. TraceQoS User Interface • TraceQoS client • Perl Script • User Parameters: • Destination host • Test port • Preferred address family (IPv4/IPv6) • Number of packets to send • Packet size • Packet rate

  7. TraceQoS Result Viewer • Dynamic display of current test traffic while in progress (OWD, OWDV, packet loss)

  8. TraceQoS Result Viewer (2) • Result visualisations of the test session (qosplot) • Can be displayed in a web-browser.

  9. TraceQoS • LIVE DEMO

  10. Implementation • TraceQoS servers connected to routers on the path to be investigated • TraceQoS client: • Traceroute to destination • Looks for matching TraceQoS servers along the path found • Sends test requests to the TraceQoS servers found • Polls packet traces from the TraceQoS servers involved • Generates statistics and displays them to the user

  11. Control protocol • Tests are initiated through HTTP (CGI) • Perl-scripts on TraceQoS servers to: • Start a sender test session • Start a receiver test session • Get current packet-trace • Stop a test session

  12. TraceQoS operating sequence

  13. TraceQoS Test Traffic • C programs to generate and receive test traffic • Fixed size UDP packets • IPV4 or IPV6 • Sent in poisson-distributed time intervals to avoid synchronization effects • Packets contain: • Test ID • Sequence number • Timestamp of sending • Padding data

  14. Interesting Test Results • NTP time drift

  15. Interesting Test Results (2) • Busy router CPU

  16. System Requirements For The Prototype • TraceQoS server: • Well-connected Linux machine(lightly loaded, short & fast connection to router) • Clock synchronization (GPS or NTP) for OWD measurements • Must be able to accept & send packets at least on UDP port 34671 (test traffic) and TCP port 80 (HTTP, control protocol) • Software: Web Server with CGI (preferrebly Apache 1.3) • Perl 5 and some Perl-libraries (libwww, file-tail, etc.)

  17. THE END Thank you for your attention! For more information about TraceQoS contact me: welti@switch.ch

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