Question
How does the Altiris Windows Agent throttle downloads?

Answer
When the agent is asked to throttle there are two methods:

1. Relative
2. Absolute

Relative: This is specified as a percentage of the available bandwidth to the server in question. When the speed for the server in question is accessed, the agent calculates the percentage it is allowed and uses that as the download target speed.

Note: Usually this does not cause any traffic on the wire because the server throughput speeds are cached for 6 hours by default. Please see the following docs for details on this process: 

Altiris Agent package download speed checks - 6.0
     Altiris Agent speed testing when ICMP is turned off
Agent Back Offs
     Altiris Agent throughput parameters
     Altiris Agent throttling operation
     Altiris Agent speed testing trigger activities

Absolute: This is specified as a specific throughput amount. The agent directly uses this quantity as the download target speed.

When throttling occurs the process is as follows:

1. Agent sets wait times and buffer sizes which most closely meet the target download speed of the relative or absolute throttle rule before starting the download.
2. It then requests a segment of data from the source.
3. It receives the data and then waits a specified period.
4. As the download occurs the agent monitors the download and adjusts to meet the specified throughput.
5. No additional speed testing is required.