Comcast, outbound dropouts, questions - Resolved

Posts: 28 · Vonage Forum Junior Joined: May 15, 2006 Posts: 28

Good news is Comcast says they are sending a "Maintenance" engineer out today (same thing as a line tech???)

Bad news is they say i have to be home. Argh. Frustrating. I've already had 2 guys out and we've replaced everything coming to the house and in the house. So, it's clearly not in my house! Can't they just hook up outside the house and see the problem???

Anyway, i'm going on 2 months now and i'm quite frustrated. Not hopeful in Comcast's ability to solve the problem.

Jeff

Posts: 6 · Posted: Fri Jun 16, 2006 4:08 pm Post subject:

A brief update from Boston -

After no real progress from Comcast over 2 months, and the outbound packet loss issue escalated to the highest levels, I tried running into my local comcast office and swapping my motorola SB5120 for another of the same. Mind you, this was done on a whim, but I had read elsewhere that some folks had seen issues with the 5120 dropping packets over time. Before I packed up the old modem, I was seeing 30% packet loss or greater to comcast.net.

Oddly enough, I fired up the new modem when I got back an hour later and had 0% loss. I've been running 1000 count ping tests and seen anywhere from 0% to 1% loss over the last two days and have my Vonage line back up and running - conversations seem to work just fine.

So, the sad part is it may just be coincidence. It's possible that Comcast finally repaired something at their end, or it's possible that the modem really was the issue. Since it's free to exchange modems, I'd suggest trying that if you're at your wits end.

For the record, here's the version info on the new modem (it's a refurb). I'm not sure if this is up to date or not.

Software Version: SB5120-2.19.0.8-SCM02-NOSH
Hardware Version: 1
MIB Version: II
GUI Version: 1.0
VxWorks Version: 5.4

I'll post again if the packet loss issue recurs.

Posts: 13 · Vonage Forum Associate Joined: Jun 08, 2006 Posts: 13

And from Dallas... a similar story!

Well, kdog, we may be onto something. Comcast tech came out and took one look at my PingPlotter logs and said, "You are right we (Comcast) have a problem." He insisted on swapping out the cable modem, an SB5120, just in case and even though the diagnostic tests on the modem showed it as working fine. He said, unless he does the swap, the home office will give him grief.

Here’s the kicker. While my packet loss is not gone, server 68.87.207.81 still has packet loss, my Vonage service works like a charm. The packet loss remains, BUT it is down to less than 20% which seems to make all the difference. So now, I have a new cable modem and Vonage service. I have only made three calls, but so far, they have been flawless.

The tech, who was knowledgeable and personable, said he would still check into the bad server hop and let me know next week.

Bottom line, IMHO, if you are on Comcast and experiencing packet loss, have them swap out your modem.

Posts: 34 · Vonage Forum Junior Joined: Jun 20, 2006 Posts: 34

Vonage-Forum

I found that changing out the modem is definately the answer, I just changed out my SB5120 to an SB3100 and found that I am not having any problems whatsoever without much sacrifice to bandwidth. I spoke with a very frank level 2 tech in our area and he informed me that a large number of the SB5120's have problems with the Comcast routers, a high % of packet loss created from the modem.

Posts: 31 · Vonage Forum Junior Joined: Jun 11, 2006 Posts: 31

That's what I'm hearing too and am going to push for a new modem. Every time I talk to tier one support they tell me my modem has lost signal hundreds of times over the prior several days - yet when the tech came out he said 'they don't know what they're talking about' and diagnosed my modem to be just marvelous. He did replace the line pole to house as the connector was corroded but alas - I knew that wasn't my problem.
So while I no doubt sit on a modem with an intermittent problem - I find it curious that trace route after trace route I get the *s every time I hit comcast Brockton, Comcast Needham, increased latency - then a guaranteed time out on hop 11 which finally turned up an IP on one particular trace - I ran an IP look up and found it to be an AT&T (owned by Comcast no doubt - they bought attbi.com) server in FL. Do you think the modem would have me flopping out on the same servers time after time? Course now they're waiting on my husband to tear apart our whole network to do the pc to modem only thing and really not willing to grasp this issue. The Vonage to Modem packet loss breaking up and drop out is really a good enough diagnostic. I wish I kept an excuse list as someone once posted - they're great! It's your computer! Which one of the 4? It's YOUR router? No, it isn't. I'm waiting for the old 'dump your netscape cache' - that's a blast from the past! I'd have to reinstall it, load up and do a dump and hey maybe - wow - everything would be all better! Still banging my head on a wall with a useless phone - but thanks for the update - will push for a new modem.
Gina

Posts: 34 · Vonage Forum Junior Joined: Jun 20, 2006 Posts: 34

I would suggest an SB5100 or an earlier modem that has support for DOCSIS 1.0, 1.1. If you have an older modem I would suggest calling Comcast and force them to let you use it. They will give you a hard time but you can get through them, make sure they not only change your mac adress to the new modem but also register it, I had to wait for 30 minutes the second call to have the modem registered so I could access the WWW.

Posts: 28 · Vonage Forum Junior Joined: May 15, 2006 Posts: 28

My weekly update: Tier 2 support finally got in touch with me. He had the ping plotter output from me and actually knew what he was looking at! Wow, that's a start.

He'll be coming out on Thursday morning to test the line. I'll see if he has a replacement modem for my 5120 as well - even though i've tried 2 others and go tthe same ping plotter results...

Jeff

PS - i also called comcast's billing department and insisted on a credit for the last 2 months of service due to the problems. They said that would not be a problem and should be processed in the next few days.

Posts: 34 · Vonage Forum Junior Joined: Jun 20, 2006 Posts: 34

Jeff,

Which modems did you use, I found that it is important which revision as well. I used a SB3100 with no revisions which supports both DOCSIS 1.0 AND DOCSIS1.1 which seems to be important.

Posts: 28 · Vonage Forum Junior Joined: May 15, 2006 Posts: 28

I've tried the 5120 (which used to work just fine) - it's DOCSIS 1.1; we tried the 4100 (which i never tried with Vonage, but noticed the SAME pattern of packet loss) and an RCA cable modem which also looked the same on my ping plots. I wasn't thrilled about having an RCA modem anyway Wink

Thanks,
Jeff

Posts: 13 · Vonage Forum Associate Joined: Jun 08, 2006 Posts: 13

Hi all,

Just a quick follow up for clarity's sake. Once they switched my modem my pingplotter tests immediately showed a dramatic decrease in packet loss, except from one server. However, my QoS score using the Voip test went from 23% to 99%. The only thing that shows as a slight problem is my jitter, but the score indicates it should not signicantly effect calls, which, so far it has not.

It sounds like we may have different problems.

Gina516, I would pretty much demand a new modem if I were you.