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| 5.2 Streaming Performance A web application is said to perform well if pages download quickly without errors. However, streaming performance is more multidimensional and complex. Akamai‘s research on how users experience streaming media has lead to the definition and measurement of several key metrics. A first metric is stream availability that measures how often a user can play streams without failures. Next, since users want the stream to start quickly, it is important to minimize startup time. Additionally, users want to watch the stream without interruptions or freezes. Therefore, a third metric measures the frequency and duration of interruptions during playback. Finally, users want to experience the media at the highest bitrate that their last-mile connectivity, desktop, or device would allow. Thus, a final important metric is the effective bandwidth delivered to the user. A major design goal of Akamai‘s stream delivery network is to optimize these metrics to provide users a high-quality experience. In addition to the key metrics above, a number of auxiliary metrics such as packet loss, jitter, frame loss, RTT, and end-to-end delay are optimized. Akamai has built and deployed a global monitoring infrastructure that is capable of measuring stream quality metrics from a user standpoint. This infrastructure includes active measurements made by agents deployed around the world. Each agent is capable of simulating users by repeatedly playing streams and testing their quality. See Section 7.5.2 for additional information on monitoring for non-streaming web content. Download 493.43 Kb. Share with your friends:
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