A tool for locating QoS failures on an Internet path 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 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

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

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

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

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

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

TraceQoS LIVE DEMO

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

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

TraceQoS operating sequence

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

Interesting Test Results NTP time drift

Interesting Test Results (2) Busy router CPU

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.)

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