link load level that activates rule enforcement

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dsalch
Posts: 123
Joined: Wed Jan 06, 2016 2:09 pm
Location: Tx

link load level that activates rule enforcement

Post by dsalch »

Interesting observation and question

It appears that QOS rules become enforced at some level of link load. Up until that point, bandwidth from any class seems able to exceed the set percentage at max load. That is, of course, a good thing.

QUESTION: what is the level of total link load at which max load percentages per class become enforced?

QUESTION: Is it possible to adjust that level? (officially or unofficially) without affecting max link load itself? In other words, enforce class max % assignments at a lower overall link load than max.

The reason that may be a positive feature, if at all possible, is this. In my system and in the previous one, there were plenty of times when for some unknown reason, max load decreased without introducing extra ping time. ACC did not detect it since ping time didnt change significantly. Therefore QOS didnt really do anything becasue rules were not enforced yet.

In my case this seems to only occur at levels between 50% to 90% of set max link load. Under 50% it doesnt seem necesary to worry about class assignments, and over 90% max load it seems that QOS is activated and enforcing limits. The land in between can be tricky, as it can randomly stop enforcing class % rules when under max link load but still dropping packets and a lesser important class overwhelms a higher importance class... all becasue ACC hasnt seen the need to activate rule enforcement.

yes, lowering the download total bandwidth fixes this problem, but at the cost of up to 50% bandwidth! Instead, wouldnt it be better to be able to enforce QOS rules at a lower level of link load? that would accomplish the same positive affect but allow actual max total bandwidth.

The same is true for UPLOAD bandwidth. If the level of link load which activates the rule enforcement could be adjusted lower, that would greatly improve effectiveness of upload QOS rules during these times.

Why does this happen? Why do packets get dropped without ping times being affected? My theory is a flakey link somewhere upstream within the ISP network. I suspect it is related to the use of WiFi based links in rural ISPs . these link can suffer times of low signal, and excessive dropped packets without actual link speed decreasing. This has an odd effect at the user end of appearing to be sporadic bandwidth limits without ping time increasing. This is likely due to ping times being once per second while the buffering around the flakey link causes more or less frequent bursts of packets. Overall it simply appears like total bandwidth jumps up or down in fractions of a second bursts, affecting come packets and not others. IT's a very weird thing to behold!

Sorry for the long post. I felt the need to explain as best I can to start the discussion. I love gargoyle, but it has a weakness in this area within the ACC mechanism. I think its related to the one second testing of ping times. But I do feel it could be alleviated greatly by simple adjusting the level at which ACC rules become enforced.

Thoughts?

pbix
Developer
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Joined: Fri Aug 21, 2009 5:09 pm

Re: link load level that activates rule enforcement

Post by pbix »

There are some fundamental incorrect assumptions in the above post. Please start by reading this from our documentation section. It will take you some time to read and understand but in the end you will understand the way QoS works.

https://www.gargoyle-router.com/wiki/doku.php?id=qos

Perhaps the most basic bad assumption above is that QoS does something in a non-saturated link. This is incorrect.
QUESTION: what is the level of total link load at which max load percentages per class become enforced?
When the WAN link reaches 100% utilization QoS starts to enforce the percentage utilization settings. Before then QoS is only monitoring what is going on. Only the "max bandwidth" setting in kbps has any meaning below 100% utilization.

Your second question is not logical once you understand the above.

ACC does not get involved in the percentage enforcement. That is the job of QoS. ACC's job is only to determine what your link can support in kbps which then becomes the definition of the 100% utilization used by QoS.
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dsalch
Posts: 123
Joined: Wed Jan 06, 2016 2:09 pm
Location: Tx

Re: link load level that activates rule enforcement

Post by dsalch »

ahh, ok. I assumed there was a level below 100% that QOS activated at. Since there isnt...

Is there any way to make that happen? It would be enormously beneficial to have QOS rules take effect at some level below 100%, in my case around 75% utilization would be awesome! Waiting for 100% utilization is fine for a perfect world, but rural america has a much less than perfect world, whether DSL or wifi. Rarely is 100% utilization achievable.

There are several ways to simulate this effect using maximum bandwidth settings, but all require some method of determining percentage of utilization and acting based on that percentage. Otherwise, it becomes necessary to sacrifice up to about 50% bandwidth by setting max at a very low level. This is a very high price to pay indeed!

ideas?

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