SB5120 & Comcast Woes

L&Gs:

I am a Comcast customer in the Atlanta area. My cable modem service is down more than it's up and I'm on this ridiculous merry-go-round, where it goes down, I troubleshoot, it's not a problem on my network, I reboot the modem, problem still exists, I call Comcast, their tech makes me do everything over, blames my network for a while, then we determine it's their problem, they reset the modem, it works for a while then goes down again, I call them back, they set an appointment for a tech to visit, the tech shows up, tests everything and it's working fine, then later that day it's dead again and I start the whole process over.

Before I give up and get DSL, I am wondering if anyone has knowledge of a utility that will allow my to monitor the availability of the internet to my computer through the cable modem and log that availability to a file, so that I can PROVE to them that it's down more than it's up. I can see that they've disabled my use of SNMP, so docsdiag won't work, but I want something a little more sophisticated than a script that will run pings and log the results to a file. Ideally, something that will grab the logs from the modem itself, save them (since there appears to be no way to do that from the Surfboard management page located at http://192.168.100.1/logs.htm), and then snapshot the power levels upstream and downstream, etc. A Motorola tech told me that have something that does exactly that but are prohibited from making it available to the customers even though many of us own our own cable modems - they claim their agreements with the cable co's prevent them from empowering us to do anything that concrete to PROVE how shitty their service is, and if Motorola breaks that rule the cable co's will just switch to other modem vendors who WON'T break it.

So there you go. I'm ot a coder and a pretty lousy scripter, so if anyone can helpme find something that'll do what I need it to do, I'd really appreciate it. Peace.

Reply to
mediumhappy
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I had similar problems until comcast came out and replaced some lines between the poles. It can also be caused by the drop from the pole to the house.

Reply to
BigJim

I use a Perl script to login and read the pages off my Terayon modem. The pages are different, but the principle should be the same.

Email me without the SPAMOLA and I'll send it to you if you like. You'll need a recent version of Perl installed (Activestate.com would be the place to get it).

Reply to
$Bill

I'm having similar problems as an ex-Comcast customer with Time Warner, but I'm still on the Comcast infrastructure. The modem web page AND Tier 3 interrogations to the modem show a low receive signal level (modem reports 15 dBmV) and tracerts show timeouts at various random nodes. The signal-to-noise-ratio is 30-34 dB. So what do they do? They try swapping modems and tightening cable connectors. Meanwhile, multiple cable TV subscribers and internet subscribers in the building are experiencing picture blocking and dropped connections and "slow surfing". It's not until I paid an unscheduled visit to TimeWarner's local warehous/field ops depot and spoke with the regional field ops supervisor did I get any action - "linemen" are coming out tomorrow to check the neighborhood curbside amplifier vault and the building's amplifier for signal levels. Until I went into their own turf to rattle their office doors did I get any attention from them that this might be THEIR problem. My impression from days on the phone with reps at various levels, including local offices, is that the transition from Comcast/Adelphia is not going well, and the techs have been swamped with calls. As a result, the feeling there is that if you get any communication at all, you're lucky, and they're not going to send out the big guns for "blocking" or "slow sufing".

Fortunately for us, people in our building are getting good service from DSLextreme and from DirecTV, so we're not locked into the "Cable Company". We can and will walk if this doesn't get fixed.

BTW, if you own your SB5120, chain it down. The database given to Time Warner by Comcast shows that the modem I had "belongs to Comcast" although I returned their Sharkfin modem a year ago and they haven't billed me for a modem since then. When the Time Warner rep tried to leave with it last week, I snarled without looking up from the monitor screen "That modem's not going to leave this room!", and he gave it back.

*TimDaniels*
Reply to
Timothy Daniels

I had a similar struggle with comcast.

I was able to demonstrate packet loss via ping -t being quite different between my computer and router, between the computer and my cable modem, and between my computer and an external site.

Similarly techs would come out repeatedly and test signal levels and all was well, they went on their way.

Until finally I begged a tech "please try another cable modem." I was leasing the modem at the time.

Ping problem, and all other intermittent problems magically gone.

This is among the reasons I continue to lease the modem--one less excuse for them to point a finger at me.

I'm also no longer with comcast, and am very damned happy. Still on cable modem just not with comcast.

Good luck!

Oh, to grab logs, a cron or at script calling wget http://urltothatlogfile would be a way to periodically go and grab. cron/wget can be had with cygwin.com shell tools.

Best Regards,

Reply to
Todd H.
15dBmV at the downstream is pretty high. I would sure like to see that down below 0. What is your transmit level?

CIAO!

Ed N.

Timothy Daniels wrote:

Reply to
Ed Nielsen

It varies around 50-51 dBmV. The low Transmit level may be low due to a high Receive level (assuming that "X dBmV" means "minus X dBmV").

*TimDaniels*

"Ed Nielsen" wrote:

Reply to
Timothy Daniels

With Comcast it's a hit or miss with service. With that in mind try

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If you are a paid member you have the option of using their 24 hour monitoring utility which might just be what you are looking for. Under their Tools section is a test called Line Quality Test. You can run this test and it will ping and run a trace route as well as a few other tests to your IP address, one from an East coast and West coast server location. As a paid member they will allow you to set this test up to for

24 hour line monitoring. It will run the test on a routine basis and log the results.
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Read here for more info.
Reply to
Jbob

The line technicians were by today, and they said the signal level on the downstream side (coming into our property) was a bit high, so they padded it down by 4-5 dB. Now the modem is reporting a downstram signal level of 9 dBmV and an upstream signal level of

47 dBmV. It had been 15-17 downstream and 50-52 upstream. I asked the tech who adjusted our amp if those numbers meant NEGATIVE dB, but he said no (which may still not mean anything).

The bottom line is that the speeds have increased a bit, but it's not really obvious due to the high variance from test to test. Tracerts are still showing timeouts, and InternetFrog.com is showing "Quality of Service" levels ranging between 9% and 50%, i.e. high retransmission rates, and the VOIP test indicates that there would be lots of dropouts and pauses. I believe it's due to congestion in the RoadRunner network.

*TimDaniels*
Reply to
Timothy Daniels

Yes, of course. The downstream value you posted WAS high and Ed pointed that out, even though you initially said you thought it was low. It should be no surprise that the line tech confirmed that it was high and therefore padded it down to a more reasonable level.

The new values look great.

No, they mean POSITIVE dB, referenced to 1 mV, i.e., signal levels that were too high, not too low. You seem to be predisposed to thinking your levels were too low. (??)

What leads you to believe it's due to congestion in the RoadRunner network?

Reply to
Bill G

needs to be in the 40's or high 30's or it'll be packetloss city in my experience, and you'll have horribly unreliable service.

How many splits occur before that cable line gets to your modem?

I've had my provider out here several times and I think we vfinally got it figured out here. DC-9 directional couplers were needed to get returnable signal to my office. These have an insertion loss of half a dB on the through leg.

Best Regards,

Reply to
Todd H.

Weather does affect these numbers in my experience.

Yeah, upstream power level is nearly always in positive dBmV. Downstream powerlevels yo ucan see in + and - territory. You had one seriously hot signal before. My downstream is -5.5dBmV right now for instance. upstream 43.50 dBmV.

Congestion shouldn't affect your signal levels. It will affect throughput and packetloss perhaps, but these signal levels it should not affect at all.

Best Regards,

Reply to
Todd H.

If it were me, Tim, I would pad that down by another 6dB, bringing the downstream down to +3 and the transmit up to around +53dBmV. Only, I would have ALL of the padding at the splitter that feeds your cable modem. If it is a splitter, perhaps change that out for a directional coupler of comparable value. Many engineers like to see cable modems run out on the hot side. It helps it to be heard over any noise that might get on the drop. 53 is perfectly fine. DOCSIS specifies a high end of 58.

Then again, if you have a DCT(digital cable box), the increase in signal level a DC would give it could cause it some grief. Might have to throw in a 3dB pad on the THRU leg of the DC.

CIAO!

Ed N.

Timothy Daniels wrote:

Reply to
Ed Nielsen

DOCSIS spec or no, in my experience on comcast and wide open west networks, upstream >50dBmV has always correlated with intermittent packet loss and frustration like the OP is experiencing. :-)

Reply to
Todd H.

He's not likely to answer for awhile as the RR news servers have been down for 5 days of "maintenance" with no estimated-time- of-completion given. TW has been *ucked up for a couple months since absorbing Comcast and Adelphia customers in November.

--------------------

***PoulStarz***
Reply to
Poul Starz

On Thu, 21 Dec 2006 19:48:48 GMT, "Poul Starz" scribbled:

Hey, why dont'cha post the same blather a few more times.

Reply to
-= Hawk =-

I have a splitter in the line for analog local stations, now, and the modem reports 7 dBmV "Downstream", and 49 dBmV on "Upstream". Access.TimeWarner still reports the same speeds in the mid-1 Mbps to low 3 Mbps, but speeds measured from SpeakEasy's Los Angeles server measure from the high 3 Mbps to high 5 Mbps, depending on the time of day and the alignment of passing meteors. Tracerts still report intermittent timeouts - most of them occuring within the RR network. I'd be trying DSL right now if it weren't for the one year committment.

*TimDaniels*

"Ed Nielsen" wrote:

Reply to
Timothy Daniels

Well, he's partially right - they're all screwed up but appear to at least accept posts.

Reply to
$Bill

Hi Tim, I think that 49dB on teh transmit side is straining things. Is this a traditional 2:1 splitter or is it a directional coupler? Try eliminating the splitter for grins and re-running

ping -t

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for a good long while to get a feel for your packetloss rate before/after the elimination of the splitter. Traceroutes aren't a great measure of packet loss.

If eliminating the splitter helps your situation, and if it's not a directional coupler/directional tap they have in there for you, call the cable company and get the tech's back out and nudge them in that direction. They can slap a directional coupler in there in seconds and it may give you another 2 or 3 dB of margin on the transmit side and make your modem happier.

Best Regards,

Reply to
Todd H.

Without the 2:1 splitter, the downstream signal level rises to 10 dBmv (from 9 dBmV) and the upstream signal level drops to 47 dBmV (from

49 dBmV). The tracerts show a quadrupling (or more) of timeouts with the splitter removed. It seems that the lower transmit level hinders the packets' survival rate, and that the splitter, in reducing the receive level, causes the modem to drop its transmit level and thus increases the timeout incidence. Is that right?

BTW, *I* put the splitter between the modem and the RR network for analog cable TV reception of local stations. Whenever the techs were here, the splitter had been replaced by a barrel connector (don't ask). As far as TW is concerned, my only service from them is RoadRunner. But no instruments measured levels within my condo unit. The only measurements that they took directly were on the level from the amp in the vault at the curb and on the output from the building's amp that resulted from their padding down the signal coming from the curb amp. The only measurements that they took specific to my modem were the remote readings reported to them from by cell phone from the central office. They said that it gave them more information than what I got from the modem's webpage and, presumably, what they could learn by tapping into the line between the wall outlet and my modem. So it's strange that the timeouts are so much less frequent when I put my 2:1 splitter in the line - it is not what they thought the usual configuration was.

*TimDaniels*
Reply to
Timothy Daniels

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