dslreports logo
 
    All Forums Hot Topics Gallery
spc
Search similar:


uniqs
14883
Emiya
join:2006-03-30
Southington, OH

Emiya to Radisc359

Member

to Radisc359

Re: Defective SB6141 Modem?

I'm waiting on the 3rd tech to come today. The last one came and definitely found an upstream issue on the main line and called for the linemen to come out. Apparently they did and 'fixed' the problem. However, I'm still getting disconnects anytime I push the upload past about 2mbps for a few minutes.
Radisc359
join:2010-10-02
Fremont, NE

Radisc359

Member

Emiya, are you getting a lot of codeword errors or just the issue while uploading? Which has to suck either way, I don't have that issue at all and my internet seems to work well with great speeds. But I had two different modems reboot twice now due to noise. Also part of the plant was bent by a tree a bit, could that cause these errors?
Radisc359

Radisc359

Member

IMHO I think SB6141's are complete junk, I've had two of them and both correctable and uncorrectable error jumps, I think I've traced it to them using a TI chipset, which I've read are less tolerant to faults. I noticed that the TI chipset isn't as accurate measuring the signal either. What I noticed with SB6141 is that it seemed to slow down any stream such as TWC's tv app for pc or amazon instant videos which caused them to buffer, but speedtests showed fine(30/5), so it took time to figure out what was causing streaming issues. So I decided to buy a Zoom 5341J because I knew something was still funny. The Zoom 5341J matches up with the signal that the cable tech was reading at the office. Even the SNR is better with the 5341J vs SB6141, 37-38 before its now 41! Correctables are now at a minimal(101 amongst 4 channels) and I have zero uncorrectable errors! So yes so far I'd recommend buying a Zoom 5341J if anyone out there is having issues similar to mine with their SB6141!

My Downstream power is a bit hot, but the SB6141 showed 7dBmV while this 5341J shows this:


motorola870
join:2008-12-07
Arlington, TX

motorola870

Member

said by Radisc359:

IMHO I think SB6141's are complete junk, I've had two of them and both correctable and uncorrectable error jumps, I think I've traced it to them using a TI chipset, which I've read are less tolerant to faults. I noticed that the TI chipset isn't as accurate measuring the signal either. What I noticed with SB6141 is that it seemed to slow down any stream such as TWC's tv app for pc or amazon instant videos which caused them to buffer, but speedtests showed fine(30/5), so it took time to figure out what was causing streaming issues. So I decided to buy a Zoom 5341J because I knew something was still funny. The Zoom 5341J matches up with the signal that the cable tech was reading at the office. Even the SNR is better with the 5341J vs SB6141, 37-38 before its now 41! Correctables are now at a minimal(101 amongst 4 channels) and I have zero uncorrectable errors! So yes so far I'd recommend buying a Zoom 5341J if anyone out there is having issues similar to mine with their SB6141!

My Downstream power is a bit hot, but the SB6141 showed 7dBmV while this 5341J shows this:
[att=1]

there also could be a firmware issue with the SB6141 showing correctable errors. I know the SBG6580 had an bug with the ARRIS C4 where you would refresh your signals and the error count would continue to go up even without downloading or uploading!
Radisc359
join:2010-10-02
Fremont, NE

1 edit

Radisc359

Member

The firmware could indeed have bugs, just look at earlier Motorola D3 modems and it took a few firmwares to get them stable, now they are pretty good. My issue seemed to affect mostly phone, internet speeds were fine while tv just had correctable errors. I had 5-6dB swings in the signal, from 5-6dBmV to 0dBmv each channel was different and it changed every time you refreshed the page, heck TWC couldn't even see my modem or mta online, the phone system checked my phone service and started to freak out because it couldn't see it, but I called in using my home phone service so obviously it was working, although I guess I sounded crappy to Tier 3. I then knew something was off when Tier 3 saw all my errors on my log, saw the signal going all over as well and agreed something wasn't right so we had a tech sent out. While all this was going on I checked myservices and the HD DVR showed up as online, while both my modem and mta said "issue found", this lasted for like 30-45 minutes then stopped. I was able to connect the signal bouncing with rapid sporadic jumps of both uncorrectable and correctable errors with a single T3-timeout.

I doubt this is it, but I believe they had my modem in the system as an SBG6580, which is Broadcom based, while we know the SB6141 is TI based, I wonder if that could cause an issue somehow? Another tier 3 I talked to to get my Zoom provisioned had to get my Zoom activated by saying it was an SBG6580, because they couldn't find a code for the 5341J, although said it was supported. The Zoom uses a Broadcom 3382 SoC while the 6580 uses the 3380 so they are much closer than the TI SB6141.

My signal never used to be 10dBmv, and that's with a 7dB(modem),7dB(mta),3.5dB(to tv 3-way splitter) 3-way splitter in Nebraska Winter Weather, so this is part higher due to the cold, possibly part of when they added a new color wavelength on the fiber. There solution was to add a 5dB splitter right before the modem to bring it down closer to 0dBmV.

»dl.dropbox.com/u/3834836 ··· r%21.PNG -- This is from the day when it jumped all over, before it was 5-6dBmv.

»dl.dropbox.com/u/3834836 ··· wsnr.PNG -- Low SNR

EDIT: Well its 18F outside and snowing, my power levels on my modem just jumped to 17dBmV up from 10, what in the world? I would say that is too much movement.

»dl.dropbox.com/u/3834836 ··· dBmV.png

motorola870
join:2008-12-07
Arlington, TX

motorola870

Member

said by Radisc359:

The firmware could indeed have bugs, just look at earlier Motorola D3 modems and it took a few firmwares to get them stable, now they are pretty good. My issue seemed to affect mostly phone, internet speeds were fine while tv just had correctable errors. I had 5-6dB swings in the signal, from 5-6dBmV to 0dBmv each channel was different and it changed every time you refreshed the page, heck TWC couldn't even see my modem or mta online, the phone system checked my phone service and started to freak out because it couldn't see it, but I called in using my home phone service so obviously it was working, although I guess I sounded crappy to Tier 3. I then knew something was off when Tier 3 saw all my errors on my log, saw the signal going all over as well and agreed something wasn't right so we had a tech sent out. While all this was going on I checked myservices and the HD DVR showed up as online, while both my modem and mta said "issue found", this lasted for like 30-45 minutes then stopped. I was able to connect the signal bouncing with rapid sporadic jumps of both uncorrectable and correctable errors with a single T3-timeout.

I doubt this is it, but I believe they had my modem in the system as an SBG6580, which is Broadcom based, while we know the SB6141 is TI based, I wonder if that could cause an issue somehow? Another tier 3 I talked to to get my Zoom provisioned had to get my Zoom activated by saying it was an SBG6580, because they couldn't find a code for the 5341J, although said it was supported. The Zoom uses a Broadcom 3382 SoC while the 6580 uses the 3380 so they are much closer than the TI SB6141.

My signal never used to be 10dBmv, and that's with a 7dB(modem),7dB(mta),3.5dB(to tv 3-way splitter) 3-way splitter in Nebraska Winter Weather, so this is part higher due to the cold, possibly part of when they added a new color wavelength on the fiber. There solution was to add a 5dB splitter right before the modem to bring it down closer to 0dBmV.

»dl.dropbox.com/u/3834836 ··· r%21.PNG

coding the modem in the system does not have anything to do with the chips in the modems. The issue with correctables was known with the ARRIS C4 CMTS and motorola DOCSIS 3.0 modems that means it was a firmware glitch showing errors that were not there I have a feeling that this bug is still present in the SB6141. I know that your problem with the phone is likely noise on the line and swings are common as the cable contracts and expands I have seen swings of 3dB to 6dB over the period of when the low temperature of the day is reached to the high of the day. I got one for you there were reports of the Cisco 10K CMTS telling 4 channel down DOCSIS 3.0 modems to stop bonding when 8 channel bonding was activated so yeah there are bugs with the CMTS and modem firmware and a bug might affect one CMTS brand while another does not have this issue. Some TWC divisions use more than 1 brand of CMTS I believe my area has Cisco 10ks and ARRIS C4s so depending on what CMTS you are on you could have firmware bugs.
Radisc359
join:2010-10-02
Fremont, NE

Radisc359

Member

Ah as I've said I knew it was far fetched, I just thought there could have been some sort of conflict, but I highly doubted that. What I was thinking that the modem was causing that noise, which would affect the mta since they use the same channels while leaving the TV pretty much alone. I don't think it had anything to do with AGC, although for some reason the 4 downstream channels are higher than surrounding qams used for TV. So what your saying about the errors sounds plausible, I should let my friend try out this modem in Lincoln and see how it works in A Cisco area vs an Arris(Me) area over like 90 days. I also read up on that Cisco cmts bug, it was interesting to see. So to move from 10 to 17dBmV is completely normal. My SNR is good and no errors are there at all even though the upper limit is 15dBmv, so it should go down once it warms up a bit.
Edison517
join:2003-07-14
Fuquay Varina, NC

Edison517 to Radisc359

Member

to Radisc359
I purchased my own modem, SB6141, when TWC started to charge me a rental for THEIR modem...but now less than a month later, I'm having connection issues, like so many others. Lots of T3 & a few T4 errors in the modem log...I found this page
»[TWC] Cable modem problems with 50/5 package in SA, TX
which talked about a guy who had 5 MAC addresses/modems listed on his account; he got them all cleared except for the one he was actually using and it fixed his problems. Are Level 3 Techs the only people who could see that? I did an instant message with a TWC rep and they said I only had one listed...

TWC sucks
Radisc359
join:2010-10-02
Fremont, NE

Radisc359

Member

I called Tier 3 and asked to have it removed yet it still shows up as deactivated. My Zoom disconnects for like 30 seconds every 2-4days, it seems to fail when it send a DHCP request, although does not reboot. It works fine until it send a request which fails and we lose internet, I'm wondering if could this be a defective modem? I'm really getting tired of this, my SB6141 acted like it was overheating and overloaded and now this Zoom disconnects every 2-4 days. I've swapped around the coax to make sure none of my cable are bad and so far it still keeps doing it. Tier 3 also said my signal was crashing on the downstream. I wonder if this could this also be my WNDR3700V2 router which has been up 20 days on the wireless radios and both work well still.

Errors in the log:
Thu Jan 10 19:57:08 2013 Error (4) Missing BP Configuration Setting TLV Type: 17.9;CM-MAC=00:1c:...
Thu Jan 10 19:57:08 2013 Error (4) Missing BP Configuration Setting TLV Type: 17.8;CM-MAC=00:1c:...
Thu Jan 10 19:57:08 2013 Warning (5) DHCP WARNING - Non-critical field invalid in response ;CM-MAC...
Thu Jan 10 19:56:54 2013 Error (4) DHCP RENEW sent - No response for IPv4;CM-MAC=00:1c:xx:xx:xx:...
Thu Jan 10 19:56:54 2013 Critical (3) DHCP RENEW FAILED - Critical field invalid in response

Signals:
Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 4 741000000 Hz 7.0 dBmV 41.4 dBmV 6438 8706
2 Locked QAM256 1 723000000 Hz 6.5 dBmV 40.9 dBmV 6251 5941
3 Locked QAM256 2 729000000 Hz 6.9 dBmV 41.2 dBmV 6412 5955
4 Locked QAM256 3 735000000 Hz 6.9 dBmV 41.4 dBmV 6213 6607
5 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dBmV 0 0
6 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dBmV 0 0
7 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dBmV 0 0
8 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dBmV 0 0

Total Correctables Total Uncorrectables
25314 27209

Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked TDMA and ATDMA 9 2560 Ksym/sec 32000000 Hz 42.3 dBmV
2 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
3 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV
4 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV

These as well:
Status
System Up Time 2 days 03h:54m:27s
Network Access Allowed

[6:57:11 PM] Server connection failed: The remote host closed the connection.
[6:57:21 PM] Reconnecting.
[6:57:22 PM] Connected.

j1349705
Premium Member
join:2006-04-15
Holly Springs, NC

j1349705

Premium Member

said by Radisc359:

I called Tier 3 and asked to have it removed yet it still shows up as deactivated. My Zoom disconnects for like 30 seconds every 2-4days, it seems to fail when it send a DHCP request, although does not reboot. It works fine until it send a request which fails and we lose internet, I'm wondering if could this be a defective modem? I'm really getting tired of this, my SB6141 acted like it was overheating and overloaded and now this Zoom disconnects every 2-4 days.

My Zoom 5341J disconnects exactly every 2.5 days, pretty much to the minute. Other than this, the modem is completely stable. The modem doesn't reboot (the system uptime doesn't change), but it loses sync and re-connects.

This type of behavior is not consistent with a bad modem. Usually a bad modem will experience issues that are totally random, or it just won't work at all. This is more consistent with a firmware bug or obscure compatibility issue somewhere. I'm not giving up on the modem, since nothing is perfect and this is something that can most likely be fixed.

Mine always disconnects right after it posts the same two DHCP errors that yours has to the log (again, every 2.5 days). It is important to realize that this is not your public IP address for your PC or router. The modem has its own IP address used for management purposes, even though the modem doesn't have any built in router or wireless functions. You may already know this... I'm bringing this up for the benefit for someone who finds this thread through a search.

One thing that wasn't clear on your post... did you talk to Tier 3 support about this specific disconnect issue, or just to remove the other modems from your account? I had to repeatedly beg a supervisor to be transferred. But once I talked to Tier 3, I was impressed. They are looking into the issue. I was told to call back after a few days to see if they have any updates. It sounds like they were going to try to find other 5341J modems to see if they all are experiencing the issue, or if there is any recognizable patter to the issue. They agreed that the DHCP errors sound like the cause for this, but they don't see a reason for them to be happening at this time.

I also talked to Zoom support. They said it sounds like a signal issue, but your signals are good and mine are good as well. There IS a newer firmware available for this modem (I'm on 5.5.4.4J and the newest revision is 5.5.4.9J). It doesn't specifically address this issue, but at the same time, it isn't unheard of for firmware updates to address something that didn't make it into the release notes.

As one final note, I tried to use the firmware update to make the lower tier "national helpdesk" escalate me, since they weren't willing to do it for any other reason. They told me that firmware updates are the customer's responsibility, which we all know is 100% false. I understand that they can't diagnose complex issues, but it would be nice if they had somewhat of a clue about how the service worked, and the ability to recognize when an issue is over their head and needs to be escalated. It didn't help that I could barely understand the support representative's accent, but the real issue was that they just didn't have a clue what was going on.
Radisc359
join:2010-10-02
Fremont, NE

Radisc359

Member

Exactly the uptime stays but it disconnects for like 10-30seconds after a DHCP request fails. Mine isn't exactly up to the minute, but that my be due to me keep rebooting it.
I had Tier 3 add my Zoom modem and it wouldn't get out of auto provisioning at first, although she did get it after a bit of trying different things. I was told there was no codes for this modem, so its added as an SBG6580. Now these two modems are both Broadcom based, but not the exact chip and the Zoom is not a gateway, so I was thinking that could why it disconnects, something is missing that the 6580 has and the Zoom doesn't. Now TWC says that they support the 5341J, so they should have a code for this modem, this could be something that an engineer needs to check into. I'm also already at 5.5.4.9J and still does it. I also always try to talk to Tier 3 if I can.