How Combined rate limit works

Started by Tony


How Combined rate limit works   25 March 2015, 14:29

Andrew, as part of a test setup, I have 1 rule active and 1 PC attached to the BWM as a test client. The rule has a rate limit of 8000000:250000 bps (8MBPS:250Kbps) through a Quota. I am testing using file downloads of various types HTTP, FTP etc.

When I don't check the 'Combined' button, BWM limits pretty well and I get nearly the expected 8Mbps download speed. Upload is minimal. However if I check the 'Combined' button, the download speed drops to about half. Given the upload is around 100kbps, I expected to to drop to about 7.5MBPS based on my reading of the manual.

Regardless of what throughput I select, I get an actual download speed which is about half of what I set. (no penalties) I can see that it is being limited.

Can you please explain the combined function or this behaviour a little for me?

SoftPerfect Support forum - Andrew avatar image

Re: How Combined rate limit works   25 March 2015, 14:50

This Combined option is only useful when you have the same rate in two directions, e.g. 100000, in this case the total of download rate and upload rate won't exceed 100000.

The formula used is (Rate In + Rate Out) / 2, so for the same rate (100000 + 100000) / 2 = 100000 and this limit is shared for both downloads and uploads.

When you use two different rates and have the combined option ticked, it will be calculated as (8000000 + 250000) /2 = 4125000 and this limit is shared for both downloads and uploads.

Re: Effect of Combined Rate limit in Rule   25 March 2015, 16:28

Thanks, that makes sense.

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