Packet discards = 68%, what can be done?

Posts: 4 · New Forum Member Joined: Jan 17, 2006 Posts: 4

I'm trying to make Vonage work for me with reasonable call quality and would really appreciate your support.

Here's my config:

1. Victoria, BC
2. Shaw cable
3. Upload 782kbps and download 3125 kbps (from dslreports)
4. Motorola SB5100 Surfboard cable modem
5. PAP2
6. Motorola---->Linksys WRT54G----> PAP2 & PC's
7. I hear callers fine, they report low volume & low voice quality.

To test the protocols I disconnected everything from my cable modem and simply connected a laptop and surfed to testyourvoip.com, which reported:

[incoming]
MOS
3.2 / 5.0
(Best with G.711 is 4.4)

Degradation Sources
Codec 0.58 31.4%
Latency 0.00 0.0%
Packet Discards 1.25 68.6%
Packet Loss 0.00 0.0%
Codec G.711 (PCM at 64kbps,
20ms RTP payload,
80kbps IP BW)
Round-Trip
Latency 170 ms
Packet Discards 3.3%
Packet Loss 0.0%
Loss Periods
Min: 20 ms
Avg: 20 ms
Max: 40 ms
Random Loss
Jitter
Min: 0 ms
Avg: 8 ms
Max: 51 ms

[outgoing]
MOS
4.4 / 5.0
(Best with G.711 is 4.4)

Degradation Sources
Codec 0.58 93.0%
Latency 0.00 0.0%
Packet Discards 0.04 7.0%
Packet Loss 0.00 0.0%
Codec G.711 (PCM at 64kbps,
20ms RTP payload,
80kbps IP BW)
Round-Trip
Latency 170 ms
Packet Discards 0.3%
Packet Loss 0.0%
Loss Periods
Min: 20 ms
Avg: 20 ms
Max: 20 ms
Random Loss
Jitter
Min: 0 ms
Avg: 0 ms
Max: 22 ms

I have placed 2 calls to Vonage tech support in the last 2 days and had my ISP (Shaw) send a technician to the house today. The Shaw tech said their connection was working 100% within spec and said they couldn't do anything about the discards.

Vonage support said they would reduce my voice quality to medium and then to low as well as setting another parameter from 30ms to 20ms. So far it has made no difference.

Is there anything else I can do? I really don't want to give up on Voip, but I don't see a solution at this point. I have a great connection to the ISP, no packet loss, decent speeds -- what else can I do?

Would switching to a different ATA made a difference? Asterisk?

Thanks in advance for your support!

Charles

Posts: 350 · Vonage Forum Evangelist Joined: Dec 04, 2005 Posts: 350

One slight note... you're actually only getting 3.3% packet discards (according to that test). However, those packet discards account for 68% of the audio quality degradation. No packet loss: good. 3.3% packet discards: workable.

First, what version of WRT54G do you have (does it have a version on the sticker on the underside)? What is the version of the firmware you are running on it? If it is the Linksys firmware, upgrade it to the latest version AND disable the SPI firewall. After doing that, retest and post your results (both the testyourvoip.com test and actual phone calls).

Posts: 4 · New Forum Member Joined: Jan 17, 2006 Posts: 4

Thanks for the clarification. I'm running a V2.0 WRT54G with the Sveasoft Talisman 1.1 firmware, however simply plugging a laptop directly into the cable modem gives me quite similar results to my initial post: most of my degeneration is due to packet discards.

When you say the situation is workable, what else can be done?

Thanks again,

Charles

Posts: 2257 · Posted: Wed Jan 18, 2006 8:46 am Post subject:

A few hints: http://vonage.nmhoy.net/packetdiscards.html

Generally, your ISP will have to deal with this issue, especially if you have already eliminated your local router as a possible cause.

3.3% discards is high, but it is random loss and not burst loss, so the people you are talking to will hear imperfect audio (tinny sound, or metallic sounds, maybe a little hissing) and generally not too much actual choppy audio or long dropouts. You'll probably be understandable, but it won't be anywhere near landline quality. With an outbound score of 3.2, and random loss, you're going to sound to the other end like you are on a slightly scratchy cell phone connection.

If your ISP is disavowing all responsibility, then there's not a whole lot you CAN do. Go to www.dslreports.com/tools and look at the tweaking section, try a newer firmware like HyperWRT in your router, etc. But if a directly-connected machine can't get the packets working correctly, I don't think you're going to be able to do anything without the cooperation of your ISP.

You could try upgrading your modem to the latest Motorola, but the SB5100 is a decent unit. Is that an ISP-provided modem? Will they allow you to swap it out?

Posts: 16 · Vonage Forum Associate Joined: Jan 13, 2006 Posts: 16

Also ask Shaw about their optional "QoS enhancement"... costs $10 extra per month. They say it's supposed to help Voip traffic. I bought it to before I got Voip to improve my real-time gaming. I believe it did make a difference. I always got 4870kbps download speed before and after the enhancement (speakeasy.net/speedtest) but now it is far less bursty. Your mileage may vary.

Posts: 4 · New Forum Member Joined: Jan 17, 2006 Posts: 4

First, thanks for taking the time to reply...I appreciate it.

NateHoy wrote:

A few hints: http://vonage.nmhoy.net/packetdiscards.html

This appears to be a broken link. I realize that packet discards are packets that are arriving out of order, and too late to be pieced together in order in the receive buffer.

Quote:

Generally, your ISP will have to deal with this issue, especially if you have already eliminated your local router as a possible cause.

This is really the crux of the matter for me. The ISP has already been out to the house and has already blessed it as having great speeds up/down, low latency and no packet loss. In their minds, there's nothing left to do.

Quote:

If your ISP is disavowing all responsibility, then there's not a whole lot you CAN do. Go to www.dslreports.com/tools and look at the tweaking section, try a newer firmware like HyperWRT in your router, etc. But if a directly-connected machine can't get the packets working correctly, I don't think you're going to be able to do anything without the cooperation of your ISP.

I suppose this answers my question above, which means Voip may not be possible for me, given the current status with the ISP. Is that really the case?

I read somewhere that if ISP's do "bandwidth shaping" or other allocation techniques, then Voip traffic could be compromised. Would any other techniques such as tweaking parameters or using a different method (IAX vs. SIP) or a different codec make a difference? I'd be willing to setup an Asterisk box to make this work if it would be worth it.

Quote:

You could try upgrading your modem to the latest Motorola, but the SB5100 is a decent unit. Is that an ISP-provided modem? Will they allow you to swap it out?

Yes, the modem is ISP-provided, though I don't see how that would make a difference, given that it is currently providing a strong signal, great dl/ul speeds, low latency and no packet loss.

To me, this is really a critical issue for Voip: Can an ISP's internal architecture make Voip a poor option for someone, or does it simply mean more tweaking?

Thanks in advance for your reply,

Charles

Posts: 2257 · Posted: Wed Jan 18, 2006 10:32 am Post subject:

Apologies... The link should be http://vonage.nmhoy.net/packetloss.html

Quote:

I read somewhere that if ISP's do "bandwidth shaping" or other allocation techniques, then Voip traffic could be compromised. Would any other techniques such as tweaking parameters or using a different method (IAX vs. SIP) or a different codec make a difference? I'd be willing to setup an Asterisk box to make this work if it would be worth it.

It might. I'd do some tests on www.dslreports.com/tools and see if you can isolate any other line problems.

I know the computer shows the same quality as the router, but your router still might be introducing delays or issues that don't fully show up on the Voip tests. Have you hooked the Vonage adapter straight to to your cable modem and tried a test call in that configuration? If that works better, you may try some other firmware in your router.

But I have to be honest, IMHO all of these are slim hopes. Your ISP connection appears to have a problem, and your ISP refuses to deal with it. Is DSL available in your area? Maybe you can use it as a threat to get your ISP to take you seriously. Maybe not.

Quote:

Yes, the modem is ISP-provided, though I don't see how that would make a difference, given that it is currently providing a strong signal, great dl/ul speeds, low latency and no packet loss.

Packet discards are a function of latency. A packet has to be delayed for some time before it is discarded. So your ISP may be right that your MODEM has low latency, but I suspect their uplink has more latency than Voip is happy with. Do some latency tests at dslreports.com and see, though.

So, if they claim the modem is running perfectly, then there's not much they will do in all likelihood. Do you know the DOCSIS version of that modem?

Posts: 16 · Vonage Forum Associate Joined: Jan 13, 2006 Posts: 16

Hey, you didnt say anything about -my- post! =p

For what it's worth, when Shaw came out to swap my old Teradyne modem for a new Motorola SB5101, my download speed went from about 1400kbs to 4870kbps and has stayed there ever since.

Posts: 2257 · Posted: Wed Jan 18, 2006 10:43 am Post subject:

Murr2k wrote:

Also ask Shaw about their optional "QoS enhancement"... costs $10 extra per month. They say it's supposed to help Voip traffic. I bought it to before I got Voip to improve my real-time gaming. I believe it did make a difference. I always got 4870kbps download speed before and after the enhancement (speakeasy.net/speedtest) but now it is far less bursty. Your mileage may vary.

INTERESTING!

So Shaw is deoptimizing traffic so they can sell you higher QoS at an additional charge.

Sweet way to make money.

Posts: 16 · Vonage Forum Associate Joined: Jan 13, 2006 Posts: 16

Well yes, they want to recover $10 a month so you dont undercut their own Voip service... they are starting to flog that now.