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No-BHELL-ity DOES have its Advantages
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2 edits
reply to Cloneman

Re: Router ALT Firmware for QoS for VoIP

said by Cloneman:

....The only setup that works perfectly is having only 2 "classes" and limiting non-voip applications to use only at most 40% of the total upload bandwidth (downstream is less important, you can give up to 85%). This is somewhat a big compromise IMO, and is to be blamed on weird quirks I've seen with both how QoS works, and how ADSL handles congestion....

It makes sense to me that we must allow such percentages, when most ISP accounts' overall upstream bandwidth is so much less than their downstream.

Mine for example (START Advanced Cable on the Cogeco AGG POI) :

16Mbps DOWN (85% for NON-VoIP leaves 15% for VoIP)
16 x .15 = 2.4 Mbps

1Mbps UP (40% for NON-VoIP leaves 60% for VoIP)
1 x .6 = .6Mbps

(If the typical 5Mbps DSL was in use, DOWN would instead be
5Mbps x .15 = .75Mbps, which would be more similar to the upstream than in my case.)

My gut feeling is that I could get away with reserving 10% DOWN for VoIP, and 40% for UP, on my particular account.


VoIP consume at most 90-ish kilobits/sec including all the overhead even with the highest quality codec at 64k bits/s. I have posted the Cisco's calculations link multiple times in the past.

The only reason why some people recommend reserving the bandwidth is to not saturate the up/down links so much to cause jitters. The right amount would be determined by how tolerate your particular ATA firmware and you to jitter during a phone call.