A framework for Quality of Service analysis of IP based video networks

Abstract

Applications that use real time video are becoming increasingly necessary for effective communication over the Internet. Their popularity is increasing in areas such as distance learning, distributed research and video conferencing. Since real time video has special Quality of Service (QoS) requirements for it to be acceptable to end users, administrators are faced with challenges that involve the end-to-end ability of participating systems to support real time video communication. Unfortunately, the tools that exist in the market today are either expensive and closed source, or are generic and do not explicitly consider the characteristics of real time video.

This work proposes a framework for assessment of end-to-end Quality of Service capabilities for support of real-time Variable Bit Rate (VBR) compressed video communication. This framework evaluates the endpoints and their inter-connectivity and determines the extent of their ability to support compressed video over User Datagram Protocol (UDP). The framework generates VBR traffic that mimics compressed low bit rate video, maintains and reports detailed and summary statistics of each test. User configurable options include specifying activity levels and bandwidth upper bounds. The framework itself is modular and extensible, allowing for functionalities to be added or replaced as the testing requirements change.

The framework defines a methodology to conduct video QoS tests, and describes how the test cycles are to be conducted for determining the Quality of Service support. Various metrics that are indicative of the Quality of Service for real time video are listed and described. Traffic generation and transmission requirements for mimicking video traffic are explained. At each participating end point, the values of the various QoS metrics are maintained in real time using specific Simple Network Management Protocol (SNMP) Management Information Bases (MIBs) designed for use with this framework.

A tool is implemented based on this framework, and its performance as a video QoS measurement tool is studied. The tool uses an Iperf based traffic generation module, that reads from trace files in order to generate test traffic. The trace files contain datagram size and timing information required to generate video-like VBR traffic. An SNMP MIB implementation is provided to record the QoS metrics determined during the tests. A separate monitoring program queries the endpoint MIBs, tabulates and displays the QoS information. This information can then be used to determine end-to-end support.