QoS: packets prioritization

[antony84]

I have a question about QoS.
I see that i can handle bandwidth for "each" services or classes, ok. But if i don't want to set tha bandwidth but only want some packets are prioritizing than others, how i can achieve this result?

Thanks for answering.

[pbix]

Set the percent bandwidth to 99% for the high priority class and 1% for the other.

[antony84]

Tnx pbix for your answer. But if i want to set three classes, which percentages i must set?

Example:
class 1 : 60%
class 2 : 30%
class 3 : 10%

Can i be sure that class 1 packets are prioritize than class2 packets and class 2 packets are prioritize than class 3 packests?

Thanks for your help.

[pbix]

What you request cannot be strictly accomplished with Gargoyle QoS. Gargoyle QoS is based on percentage utilization and not priority. You can approximate what you request by using the percentages as you describe. However, some class 3 packets will transmit even when class 1 packets are waiting according to the percentages you select.

[antony84]

Thank pbix, but i don't understand the behaviour of QoS Gargoyle.
I understand only that bandwidth are divided at capacity, according with percentage and/or minimum bandwidth.
But if the bandwidth is not at capacity, which packets are prioritize? It is FIFO management?
Can i be sure at least that class packets with "percentage=1% and 80kpbs minimum bandwidth" are prioritize more than other classes without minimum bw?

I think a tutorial for QoS Gargoyle is nedeed! It is no so clear!

P.S. I know that bandwidth is not the only things that QoS can do. I read about qos-script for openwrt, and if i understood correctly, it is only packets prioritizing, without bandwidth management. There is a method for combining both the QoS management?

Thanks a lot for your support and help

[pbix]

If the link is not at capacity then the percentage values and minimum bandwidth have no real meaning. These things only have meaning if you have to wait.

When the link is not at capacity and a packet arrives in the router it immediately gets transmitted. The link is waiting for data so why should we not send it? That would waste bandwidth.

Max bandwidth does have meaning however when bandwidth is not saturated because even if bandwidth is available the class is not allowed to exceed it's defined maximum bandwidth.