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Kardos

join:2008-04-07

Tomato QOS question

Hi all,

Just set up QOS on Tomato but it's not working quite right. I'm trying to prioritise SSH traffic over "bulk" traffic... so "bulk" traffic uses all upstream when SSH is idle, but let SSH traffic use all available upstream when in use.

So first question, on QOS->Basic Settings, what does the first column of percentages do? The second column makes sense ("maximum percentage of upstream allowed for this class"), and for lowest-priority it does indeed cap bulk traffic at 60% of 800kbps. I don't understand what the "2%" does.

Second issue... my current setup is almost doing the Right Thing. The bulk traffic is indeed capped at 60%, but when I start SSH traffic it does not exceed the remaining unused 40%. The desired result is to let SSH dominate and use 90%+ of upstream, and essentially stall the bulk traffic. How would one adjust the settings make it do that?

Here are my settings,

Basic QOS:


Classifications:


Cheers

Kardos


planiwa

join:2009-02-19
Toronto M5S
kudos:1

min%-max%

The class is guaranteed min% of the total bandwidth as specified.
The class may use up to max% of the bandwitdth, if no higher class traffic is waiting.

The total of the min% should therefore not exceed 100%.
The specified total bandwidh should be no more than 90% of the lowest actual measured bandwidth. Setting it too high is like pretending you have more money in the bank than you do. It will fail when you need it.

Your theoretical maximum throughput is about 85% of the sync rate. That is assuming packets specially constructed to minimize packaging overheads. Real-life net traffic is about 80% of gross. For a sync rate of 800, that would be 640. 90% of that is 576. Use that or less for QOS.

As a consequence, for QoS to work at all, you have to reduce your effective bandwidth.