Question Regarding QOS and "bursting" speeds

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thecgmguy
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Question Regarding QOS and "bursting" speeds

Post by thecgmguy » Fri Feb 25, 2011 10:47 am

Hi Guys,

I'm using comcast and my upstream bursts to 3 Mbps but falls back to 1 Mbps for lengthy/large uploads. I know that the upstream QOS recommendation would be 85% of the speed value but should I set it to 85% of the bursting speed or the standard speed?

Thanks,

M

murphy
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Re: Question Regarding QOS and "bursting" speeds

Post by murphy » Fri Feb 25, 2011 1:07 pm

Standard speed. The burst doesn't last very long.
Customer since January 2009
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cm2va
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Re: Question Regarding QOS and "bursting" speeds

Post by cm2va » Fri Feb 25, 2011 2:55 pm

thecgmguy wrote:Hi Guys,

I'm using comcast and my upstream bursts to 3 Mbps but falls back to 1 Mbps for lengthy/large uploads. I know that the upstream QOS recommendation would be 85% of the speed value but should I set it to 85% of the bursting speed or the standard speed?

Thanks,

M
I know what I'd set it to if it were a "real" router, but they abstract the real operation by their user friendly interface. You want to set up a priority queue to handle the capacity of as many phone calls as you can make. This will likely be less than 100K. The rest of your network traffic should be handled by a lower priority queue. You'd also want to shape the outbound traffic so that the traffic isn't discarded indiscriminately by the carrier. If you shape it, then you can decide what traffic to drop ... and it will never be voice.

So the question is, "What does that value do?" What queuing scheme is the device using - there are many, and they all use a variety of bandwidth values for the different queues.

I can only guess that the value you configure is the shaping rate and the Ooma carves out a queue big enough for your voice call(s) because it knows what bandwidth they'll be using. If you shape at 1M you won't be able to burst to 3M - the Ooma will limit you. If you shape at 3M you may end up getting some loss during upstream congestion. Play it safe or gamble and get more upstream capacity?

Does anyone know what these settings actually do?

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lbmofo
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Re: Question Regarding QOS and "bursting" speeds

Post by lbmofo » Fri Feb 25, 2011 3:01 pm

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lbmofo
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Re: Question Regarding QOS and "bursting" speeds

Post by lbmofo » Fri Feb 25, 2011 3:02 pm

I'd use whatever is measured by speedtest.net
Take many readings at different times of the day and use an average; discount that by 20%.
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cm2va
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Re: Question Regarding QOS and "bursting" speeds

Post by cm2va » Fri Feb 25, 2011 3:18 pm

Thanks. That confirms that this is the shaping rate and the Ooma device carves out what it needs for voice in a priority queue.

So, if you play it safe and shape on the low side, you'll be assured your voice traffic isn't discarded on the wire, but you'll only get that much upstream throughput. If you use a higher number, you'll get better throughput for your other apps, but you may suffer on voice quality.

With DSL, the link capacity is a pretty solid ceiling; you could shape right at your DSL line rate. Cable is a shared media, so your available bandwidth depends on what other customers are using.

thecgmguy
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Re: Question Regarding QOS and "bursting" speeds

Post by thecgmguy » Fri Feb 25, 2011 4:08 pm

cm2va wrote:
So, if you play it safe and shape on the low side, you'll be assured your voice traffic isn't discarded on the wire, but you'll only get that much upstream throughput. If you use a higher number, you'll get better throughput for your other apps, but you may suffer on voice quality.
The bandwidth throttling is only in effect when people are on the phone though right? For example, I set the QOS to 850 Kbps but I'm still getting 3 Mbps upload speeds on speedtest.net

If that's the case, I can live with occasional upstream speed issues if Ooma calls will be clear. Especially since I only use the phone a 5 - 10 times per day.

-M

thecgmguy
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Re: Question Regarding QOS and "bursting" speeds

Post by thecgmguy » Sat Feb 26, 2011 10:43 am

Interestingly enough, I contacted ooma support and they suggested setting upstream QOS to 756 and downstream QOS to 2350.

I completely understand the upstream part... but the downstream seems a little excessive. Anyone else have their downstream QOS set this low?

I'm going to try 756 Up QOS and 5000 Down QOS (which is still at least 1 Mbps below my standard speed rate).

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Re: Question Regarding QOS and "bursting" speeds

Post by lbmofo » Sat Feb 26, 2011 7:25 pm

I'd disable downstream QoS by setting to 0.
U can do speedtest while on call, while no call to compare QoS effects.
Customer Since: 3/13/10
Hardware: Telo & Hub
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