Troubleshooting Voice Drop outs. Best Practices?

[Dave_N]

Hi,

I have recently cut over to voipo residential service. I am having voice drop outs in my service on nearly every call. Interestingly, calls to voice mail are okay. I haven't checked, but perhaps voice mail uses 80ms packets instead of 20ms packets?

This leads me to believe that my router (or my comcast service may not be up to snuff.)

So my network is as follows:

cable-->Motorola Sb5101 --> Netgear 824v2 -->linksys PAP2 (in DMZ)
\--> 4 wireless devices
\--> 2 wired devices

When I test for speed at Broadband test results I usually get about 5 Mbits down and 768Kbps - 1 Mbps. Doesn't seem to be a bandwidth issue. Similiarly when I ping I get decent response time so it doesn't seem to be a latency issue. This leads me to suspect that the router is dropping (or delaying) packets, but I don't know of a simple way to test this.

Since the PAP2 does a 10M link to the netgear, I should be able to insert a hub on this link and get a wireshark trace going. I have not done this yet.

Now, I know that MGCP endpoints support per call statistics, but most SIP devices do not. I called support last night and they said that they would enable extra logging but I am away from home right now so I can't place a call and replicate the issue.

Does anyone have any trouble shooting ideas?

Thanks,

Dave

[VOIPoTim]

Dave,

Has anyone mentioned having us fully handle your audio vs us redirecting it back out to Level3 media gateways?

Since you said voicemail works fine (audio is internal), it sounds like that could be a good solution for you.

[Dave_N]

Dave,

Has anyone mentioned having us fully handle your audio vs us redirecting it back out to Level3 media gateways?

Since you said voicemail works fine (audio is internal), it sounds like that could be a good solution for you.

Nope, I was trying to verify my end first.

I find it helpful, and often correct, to blame myself first. ;D

Dave

[sr98user]

Try the following voip test sites

http://www.testyourvoip.com
http://voiptest.nuvio.com/

See what kind of results you get.

I took a quick look at the Netgear 824 manual. And it does not have any QOS. If VOIP packets are competing with any other traffic from your network, there will be quality issues.

[Dave_N]

Try the following voip test sites

http://www.testyourvoip.com
http://voiptest.nuvio.com/

See what kind of results you get.

I took a quick look at the Netgear 824 manual. And it does not have any QOS. If VOIP packets are competing with any other traffic from your network, there will be quality issues.

Yes, I was aware of the lack of qos. That was one reason I wanted to get hub on it and see what is happening.

By the way, do we know what a "good" router with qos is? I see the DL link 655 seems highly rated. It has "automated qos". I have no idea what that means. I would prefer a simple port priority scheme to give priority to the PAP2 media streams and the PAP2 sip signaling. Perhaps UDP priority would be enough.

[sr98user]

I don't have personal experience with DL-655. But others at dslreports have not said anything bad about it.

For some of the QOS routers, just turning it on will be enough. The RTP packets are marked with a IP precedence 5 and they are automatically given high priority. On some routers, you would have to give priority by MAC address. In this case all packets coming out of that MAC will be given highest priority. On more expensive routers, you can match packets based on your own criteria and give those packets specific bandwidth.

Many users have good results with getting a simple G router and flashing it with Tomato/DDWRT. Some of good ones mentioned are Trendnet 631, ASUS 520GL, etc.. You can also get a better Netgear model and try it out. See if it works well during upload/download. Make sure you are able to return it without restocking fee if you want to just try some from retail stores.

[quattrohead]

Try or borrow any other router. The Netgear FVS318 is a slow device in general for example, perhaps the 824 is not to special either. Even the $40 white wireless netgear router is significantly better than the 318.
I just switched to a Linksys running tomato and the whole network seems better.

[Dave_N]

And I spoke too soon. I am having drops with voice mail.

[Dave_N]

http://i.dslr.net/imc/0/0/2/9/68742758.png

It ain't bandwidth.

[Dave_N]

http://picasaweb.google.com/lh/photo/KywGk5auDLdwXhoHeyowtQ?feat=directlink

Test my voip says it is latency and loss.

[Dave_N]

nuvio agrees:

Speed
-----
Download speed: 5702248 bps
Upload speed: 5279472 bps
Quality of service: 7 %
Maximum TCP delay: 212 ms
Average download pause: 3 ms
Minimum round trip time to server: 52 ms
Average round trip time to server: 54 ms

VoIP
----
Jitter: you --> server: 18.1 ms
Jitter: server --> you: 32.5 ms
Packet loss: you --> server: 0.0 %
Packet loss: server --> you: 0.0 %
Packet discards: 0.0 %
Packets out of order: 0.0 %
Number of VoIP lines supported: 41
Estimated MOS score: 3.7

Speed test statistics
---------------------
Download speed: 5702248 bps
Upload speed: 5279472 bps
Quality of service: 7 %
Download test type: socket
Upload test type: socket
Maximum TCP delay: 212 ms
Average download pause: 3 ms
Minimum round trip time to server: 52 ms
Average round trip time to server: 54 ms
Estimated download bandwidth: 16000000bps
Route concurrency: 2.8059108
Download TCP forced idle: 40 %
Maximum route speed: 10082304bps

VoIP test statistics
--------------------
Jitter: you --> server: 18.1 ms
Jitter: server --> you: 32.5 ms
Packet loss: you --> server: 0.0 %
Packet loss: server --> you: 0.0 %
Packet discards: 0.0 %
Packets out of order: 0.0 %
Estimated MOS score: 3.7

Streaming video statistics
--------------------------
Audio stream jitter: 62.1 ms
Video stream jitter: 62.1 ms
Audio stream packet loss: 0 %
Video stream packet loss: 0 %
Audio stream packet discards: 0 %
Video stream packet discards: 0 %

Capacity test statistics
------------------------
Download capacity: 1981600 bps
Download packets per second: 1548
Upload capacity: 948616 bps
Upload packets per second: 741
Quality of service: 97 %
Packet size: 160 Bytes

[sr98user]

Nuvio says your upload bandwidth is 5279472 bps (5M). Is that really true? I think you posted another speed test which shows 2.6 (M). Assuming its something close to it, I think the problem is not bandwidth. If you can just give your VOIP packets higher priority, I think you will be good to go. You have some jitter in the VOIP section which might be caused by the router. It could be your line too. But given the speedtest, I would lean more towards router issues

[Dave_N]

Nuvio says your upload bandwidth is 5279472 bps (5M). Is that really true? I think you posted another speed test which shows 2.6 (M). Assuming its something close to it, I think the problem is not bandwidth. If you can just give your VOIP packets higher priority, I think you will be good to go. You have some jitter in the VOIP section which might be caused by the router. It could be your line too. But given the speedtest, I would lean more towards router issues

I tend to agree that it is pointing to jitter. To the ear, it's hard to discern jitter versus loss because I presume the device discards the late packets. I did more nuvio testing in front and behind the router with my pc. In front of the router I get all green for the voip, behind I get red/yellows for qos and jitter, so it is pointing to the router. I'll look into to getting a better router. It is interesting that for the nuvio video test, it also doesn't like the jitter.

I know of Tom's hardware / Small net builder for router reviews. Are there other sites?

Thanks,

Dave

[1bird2]

Tomato. Google Tomato Firmware. FInd a Linksys WRT54g on ebay. What I do for myself and recommend to others. Words fantastic and is cheap!!

-bird

[Dave_N]

Couldn't find a Tomato compatible router locally. Couldn't wait for the ebay shipping time with the current WAF (Wife Acceptance Factor). I acquired a Dlink DIR-655 with decent reviews and automatic QoS. So far so good. No dropouts and no "forgetting" of inbound port configuration.

For the record, Netgear 824v2 doesn't work very well for voip. It did give me several years of solid service as a standard router.