QOS and my cable modem

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QOS and my cable modem
Posted Tue, 04/29/2008 - 23:38
I have been experiencing poor audio on my voip from Vonage via my Comcast cable connection (Linksys BEFCMU10 Cable Modem). I ran the voipreview.org test and got the following: When: Thu Nov 09 09:39:44 EST 2006 Download: 14,057,144 bps Upload: 368,016 bps QOS: 28% RTT: 18 ms MaxPause: 11 ms I called Comcast complaining that my QOS is LOW. They came out and tested and to them (not sensitive to the QOS metric) they were excited about the 14mbps download and the 368mbps upload. Something they allow called bursting. The tech took my Linksys cable modem out and installed their Motorola SB5120 modem and we tested the line again. Download speed: 8461248 bps Upload speed: 961728 bps Quality of service: 99 % Download test type: socket Upload test type: socket Maximum download pause: 21 ms Average download pause: 4 ms Minimum round trip time to server: 19 ms Average round trip time to server: 19 ms NOTE THE DOWNLOAD SPEED DROP from the bursting, 14mbps speed of the Linksys versus the 8.4mbps of the Motorola cable modem. QUESTION?????? If QOS is a measure of the minimum speed observed during a large download divided by the maximum speed observed what effect is the Linksys's capability to handle bursts up to the 14mbps area have on my test results and resulting 28% QOS number???? My guess is that the QOS calculation is just that a calculation and is a bit misleading when it looks the minimum (3.9mbps) and the maximum (14mbps) it results with the given 28% QOS. When we swapped out the cable modem the QOS went up to 99% but it was based on the minimum (8.37mbps) and the maximum of (8.46mbps). Does it make that much of a difference to the VOIP call? If I have a minimum of 3.9mbps with my Linksys and love the burstability of the high 14mbps whats a guy to do? I guess I can give up the high burst for the increased minimum but... is it really necessary???? I guess it is down to buying another cable modem and trying it. HMMMMMMMMMMMM Any thoughts from anyone?
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Comments

Re: QOS and my cable modem

Tue, 04/29/2008 - 23:38 — Archives
In your case your low QOS isn't going to hurt you because the minimum speed is so high. You want to pay attention to Jitter, max round trip time, etc. It sounds like you connection is screaming fast and VoIP should have 0 problems unless you have some kind of intermittent quality issues. Are you having issues with your voip calls?

Re: QOS and my cable modem

Tue, 04/29/2008 - 23:39 — Archives
There are some other things that could cause poor audio quality. 1. Others systems on the network with a virus. I actually have personally experienced this. If a virus is running creating requests it would slow down your connection. 2. Your router configuration. 3. Vonage's settings. They may need to adjust some settings so call them.

I would keep the high download speeds

Tue, 04/29/2008 - 23:39 — Archives
Because your upload and download speeds are so good - there may be another problem here. I have voip and had a problem with my ATA and router conflicting with one another. I was able to solve this by updating the firmware on my router (be very careful doing this and follow the directions the manufacturer of your router has on its website). Sometimes changing having the ATA device plug into the modem or into the router can help (one may work better than the other) Note: You only need 90 kbs up/down to have a good quality call with voip. Your up/down is way over that. If you haven't already, try using the new voip speed test at http://www.voipreview.org/voipspeedtester.aspx (new as of this month). Get readings on jitter, packet loss, etc. - may tell you more. Because you have cable internet service - you may have a neighbor or neighbors that also have cable internet and are effecting the line by their use. Hope this helps.