High jitter and poor latency issues

**Aubie** · October 17th, 2012, 07:04 PM

I have cable with a local company and have been experiencing a lot of problems with applications requiring low amounts of latency. The biggest problem I am having is with my Vonage phone setup. I can hear everyone on the thing perfectly fine, but several times a day I start cutting out and eventually become completely garbled to the receiver.

I have had the cable company out here many times. They keep testing the modem and the lines and finding no problems. Today they replaced the modem but a few hours later I started cutting out again and had to switch to my cell phone. So I decided to run some tests and found that the first switch after my cable modem is dropping 100% of packets sent to it. I am not sure why I would sometimes be alright while talking on the phone and other times not because of this, but that's the only problem I have found.

I have been monitoring the SNR and power levels (upstream and downstream) and when the problem isn't occuring they are in a pretty good range. Well, I am experiencing the issue right now and I noticed the downstream power level has dropped to -0.7 dBmV and I seem to remember it being around +4.7dBmV yesterday.

Additional tests came from pingtest.net where my ping was 141ms and my jitter was 111ms. And this problem is intermittent, so in another 30 minutes it will probably clear up (but I'm not sure for how long).

I have the cable model going straight to my desktop computer. No routers in the line at all. I also do not have cable television so there is not a single splitter in the line. This problem occurs when I connect my router as well but for now I am leaving it unplugged to silence the techies that keep trying to blame it on the router.

A screenshot of some of my findings can be found here:

Image - TinyPic - Free Image Hosting, Photo Sharing & Video Hosting

So my question is, will the first hop dropping 100% of packets possibly lead to the symptoms I have seen (high jitter periodically but fine at times). If so, how can I make the cable company fix the problem? The tech today told me he doesn't even normally do a pingtest when he goes out to troubleshoot. I found it odd that something so important was completely skipped.

**Taxmancometh** · October 17th, 2012, 11:44 PM

I'm assuming you have Internet Via cable, correct? If so have the technician do a ingress test on the drop that goes to the tap and your network interface box.

This doesn't have anything to do with Internet in my case, but TV. We were having problems with certain channels and we had tech after tech come out to look at it and found nothing. Then we had this tech do an ingress test on the drop and found a ton of ingress. The guy was a foreigner too!