Time to First Buffer Breakdown Graph

This graph displays each Web page component's relative server/network time (in seconds) for the period of time until the first buffer is successfully received back from the Web server.

Note: This graph is only relevant when the load generator does not use a proxy to connect to the application under test. If the load generator is connected through a proxy, this graph will only show the proxy latency—not the application's latency.

Purpose

If the download time for a component is high, you can use this graph to determine whether the problem is server- or network-related.

X-axis

Specifies the name of the component.

Y-axis

Shows the average network/server time (in seconds) for each component.

Measurements
  • Network time is defined as the average amount of time that passes from the moment the first HTTP request is sent until receipt of ACK.

  • Server time is defined as the average amount of time that passes from the receipt of ACK of the initial HTTP request (usually GET) until the first buffer is successfully received back from the Web server.

Note
  • Each measurement displayed on the page level is the sum of that measurement recorded for each page component. For example, the network time for www.cnn.com is the sum of the network time for each of the page's components.

  • Because server time is being measured from the client, network time may influence this measurement if there is a change in network performance from the time the initial HTTP request is sent until the time the first buffer is sent. The server time displayed, therefore, is estimated server time and may be slightly inaccurate.

  • The graph can only be viewed as a bar graph.

See also

Web Page Diagnostics Graphs Overview

Example

In the following example it is apparent that network time is greater than server time.

Example

You can break the main cnn.com URL down further to view the time to first buffer breakdown for each of its components. It is apparent that for the main cnn.com component (the first component on the right), the time to first buffer breakdown is almost all network time.

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