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Contributor
ezhilk
Posts: 10
Registered: ‎07-24-2012
Accepted Solution

Motorola SB6121 upstream power level and modem reboots

Hi everyone, 

 

I have been using a Motorola SB6121 modem for the last three weeks and have been experiencing the same timeout issues and modem reboots that a lot of others seem to be having. I had tech come in and take a look at the signals that come into the apartment and also at the modem and whoever visitied my apartment told me it was the signal and not the modem that was causing the issue. So line maintenance was called in and they did some work at the tap I believe, which brought down my previously high upstream power levels from around 51 - 52 dbmv to 47-49 dbmv. 

 

But I am still experiencing the reboots every now and then. I have asked Comcast to have the line maintenance look at the signals at the tap again, but I am not sure if it is the signal issue that is causing the reboot or if something is wrong with my modem. Any thoughts will be much appreciated, as the window to return my modem closes in another week and I would rather have it replaced if the modem is the issue.

 

 

The stats for the modem are as follows :

 

Downstream Bonding Channel Value Channel ID 3  4  6  7  Frequency 699000000 Hz  705000000 Hz  717000000 Hz  723000000 Hz  Signal to Noise Ratio 36 dB  36 dB  36 dB  36 dB  Downstream Modulation QAM256  QAM256  QAM256  QAM256  Power Level The Downstream Power Level reading is a snapshot taken at the time this page was requested. Please Reload/Refresh this Page for a new reading 1 dBmV   0 dBmV   0 dBmV   0 dBmV  

 

Upstream Bonding Channel Value Channel ID 3  1  2  Frequency 24200000 Hz  36400000 Hz  29500000 Hz  Ranging Service ID 1675  1675  1675  Symbol Rate 2.560 Msym/sec  5.120 Msym/sec  5.120 Msym/sec  Power Level 47 dBmV  47 dBmV  47 dBmV  Upstream Modulation [3] QPSK
[2] 16QAM
  [3] QPSK
[3] 64QAM
  [3] QPSK
[3] 64QAM
  Ranging Status Success  Success  Success 
Connection Expert
EG
Posts: 40,224
Registered: ‎12-24-2003

Re: Motorola SB6121 upstream power level and modem reboots

The upstream is better but it is still on the higher side. Is it remaining stable or do you notice it still going over 50 dB intermittently ? Please click on the modem's "Help" tab in the U.I. and post which version of firmware that it currently has.

 

If you are thinking of returning it you may want to consider getting a Zoom 5341"J" (note the J) model instead. It is an 8x4 and not just a 4x4 multiple channel bonding capable model modem as is the 6121. It appears to be much more stable and more forgiving / tolerant than these 6120's & 6121's and is even more future proofed. We have seen nothing but good reports about it here and at other forums. I've using one for eight months and it's been bulletproof !

 

If you have enough time, you could try renting a different make and model number modem from them as a test for just one month and see what happens.

Contributor
ezhilk
Posts: 10
Registered: ‎07-24-2012

Re: Motorola SB6121 upstream power level and modem reboots

Thanks EG. I do see all three channels having upstream power levels at 50 db a couple of times, and one of them tipped over into 51 db as well. The last time it reset though, I noticed that the status was "Retries exhausted" or something to that effect on two of the channels and the power level was 47 and 48 on those two channels - this is what made me suspect if my modem could be defective.

 

I will post the firmware version once I get back home. 

 

And thanks for the suggestion for the modem. I might be actually returning the 6121 and give Zoom a shot if it is more forgiving for these power levels. 

Contributor
ezhilk
Posts: 10
Registered: ‎07-24-2012

Re: Motorola SB6121 upstream power level and modem reboots

[ Edited ]

Here is the firmware details for the modem:

 

Model Name: SB6121
Vendor Name: Motorola
Firmware Name: SB_KOMODO-1.0.6.6-SCM00-NOSH
Boot Version: PSPU-Boot(25CLK) 1.0.12.
Hardware Version: 5.0
Serial Number: 359079213727462901012019
Firmware Build Time: Apr 17 2012 15:09:37

 

Also checked my connection now and found that it has been up for almost 11 hours without any interruption and the upstream levels are around 47 on all three channels. Not sure if this is a good sign that things have stabilized...

Connection Expert
EG
Posts: 40,224
Registered: ‎12-24-2003

Re: Motorola SB6121 upstream power level and modem reboots

[ Edited ]

Just wanted to see if you got it yet as there have been lots of firmware issues reported with that modem as of late but you do indeed now have the latest firmware load that they have been pushing for it (within the past couple of days and today in many areas as a matter of fact) which is supposed to be a fix and make the modem more stable. Some posters on other forums have been posting that it has helped and some are not.. This isn't a magic fix for connection quality issues with the lines and they will still be there regardless of firmware if they do indeed exist. They only way to tell for sure is to live with it for a while to see what happens.

Contributor
ezhilk
Posts: 10
Registered: ‎07-24-2012

Re: Motorola SB6121 upstream power level and modem reboots

[ Edited ]

I do see from the logs that something was downloaded onto my modem at 2 AM today. Maybe that is the firmware patch ?

 

Jul 24 2012 02:07:34 6-Notice E112.0 SW download Successful - Via Config file

 

But I do find that my modem has restarted twice after that with the same T3 timeout errors. Maybe it didn't fix the issue for my modem afterall :smileyhappy:. I guess I will go ahead and place an order for the Zoom modem and see how the 6121 performs in the time it takes for that to arrive.

Connection Expert
EG
Posts: 40,224
Registered: ‎12-24-2003

Re: Motorola SB6121 upstream power level and modem reboots

Yep. That's it. Hope that my recommendation serves you well. My disclaimer is "your mileage may vary". Good luck with whatever you decide ! :smileyhappy:

Contributor
ezhilk
Posts: 10
Registered: ‎07-24-2012

Re: Motorola SB6121 upstream power level and modem reboots

[ Edited ]

Thanks for the help EG. I've ordered the Zoom modem, and my connection has been holding steady with the 6121. Hopefully one of them will solve my troubles :smileyhappy:

Connection Expert
EG
Posts: 40,224
Registered: ‎12-24-2003

Re: Motorola SB6121 upstream power level and modem reboots

Curious as to know the outcome. Please update !

Contributor
ezhilk
Posts: 10
Registered: ‎07-24-2012

Re: Motorola SB6121 upstream power level and modem reboots

Well, that software update definitely improved the performance a lot (connection was dropping only once or twice a day) but did not remove the problem entirely (lost connection thrice in the evening yesterday). So I decided to go ahead with the Zoom modem which I got today and I promptly returned my SB6121.

 

Well, now I am having troubles with the Zoom 5341J :smileysad:

 

Got the modem today, got online to ask Comcast to provision it which the rep did. But my modem was unable to establish a connection for sometime. And it eventually did, but it has not been able to hold a connection since and keeps rebooting every five minutes, just like my motorola modem used to. The comcast rep blamed it on the modem and asked me to get a new one. I tried resetting it to the factory settings twice or thrice but it keeps losing the connection and resets again and again. 

 

Where do I go from here. 

 

This is the log I see everytime I reset to the factory defaults and connect again. Is it a modem issue or a line issue ? Sadly, I don't even have my old modem to check the line (the last day to return was tomorrow and I had to get it out by today..)

 

 

 

 

Time 

 Priority 

 Description 

 Fri Jul 27 14:55:19 2012  

 Critical (3) 

 SYNC Timing Synchronization failure - Loss of Sync;CM-MAC=00:... 

 Time Not Established 

 Warning (5) 

 DHCP WARNING - Non-critical field invalid in response ;CM-MAC... 

 Fri Jul 27 14:54:34 2012  

 Notice (6) 

 SW download Successful - Via Config file 

 Fri Jul 27 14:53:31 2012  

 Notice (6) 

 SW Download INIT - Via Config file d11_m_5341j_silver_c01.cm 

 Time Not Established 

 Warning (5) 

 DHCP WARNING - Non-critical field invalid in response ;CM-MAC... 

 Time Not Established 

 Critical (3) 

 No Ranging Response received - T3 time-out;CM-MAC=00:1c:7b:c8... 

 Time Not Established 

 Critical (3) 

 SYNC Timing Synchronization failure - Failed to acquire FEC f... 

 

Contributor
ezhilk
Posts: 10
Registered: ‎07-24-2012

Re: Motorola SB6121 upstream power level and modem reboots

And my signal levels from the 5341J if it helps..

 

 

Startup Procedure Procedure Status Comment Acquire Downstream Channel 729000000 Hz Locked Connectivity State OK Operational Boot State OK Operational Configuration File OK   SecurityEnabled BPI+

 

Downstream Bonded ChannelsChannel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables 1 Locked QAM256 8 729000000 Hz 1.9 dBmV 38.2 dBmV 0 0 2 Locked QAM256 1 687000000 Hz 2.9 dBmV 38.6 dBmV 0 0 3 Locked QAM256 2 693000000 Hz 3.2 dBmV 38.2 dBmV 0 0 4 Locked QAM256 3 699000000 Hz 3.0 dBmV 38.2 dBmV 0 0 5 Locked QAM256 4 705000000 Hz 2.8 dBmV 38.3 dBmV 0 0 6 Locked QAM256 5 711000000 Hz 2.3 dBmV 38.2 dBmV 0 0 7 Locked QAM256 6 717000000 Hz 2.4 dBmV 38.2 dBmV 0 0 8 Locked QAM256 7 723000000 Hz 2.0 dBmV 38.2 dBmV 0 0

 

Total Correctables Total Uncorrectables 0 0



Upstream Bonded ChannelsChannel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power 1 Locked ATDMA 2 5120 Ksym/sec 29500000 Hz 46.0 dBmV 2 Locked ATDMA 1 5120 Ksym/sec 36400000 Hz 46.0 dBmV 3 Locked TDMA 3 2560 Ksym/sec 24200000 Hz 46.0 dBmV 4 Not Locked Unknown 0 0 Ksym/sec 0 Hz 0.0 dBmV

 

Recognized Contributor
MikeWolf
Posts: 581
Registered: ‎10-11-2011

Re: Motorola SB6121 upstream power level and modem reboots

[ Edited ]

You just might need to have a tech come out and tweak the line outside the house, or perhaps it could be a splitter issue. Signal levels can change depending on environmental and weather conditions so sometimes it can be more difficult then what is ideal.  If you would feel better exchanging the modem for another 6121 then that would be an option that couldn't hurt you either way. 

 

In most cases an 8x8 modem is overkill.

Say you install a 4x4 modem in an area where Comcast is offering 8 bonded channels, when the modem boots up it scans the available channels with the best signal quality and chooses the best four, lets say channels 1, 2, 4, and 7. The modem monitors the quality of the signal and if it becomes unacceptable it will rescan and look for another stronger channel signal out of the surplus 4 channels left over such as channel 3, 5, 6, and 8.  This same practice can be used for areas with 16 channels available and so forth. A 4 channel modem gives a downstream speed of 171.537Mbps combined or 42.884Mbps per channel where as an 8 channel modem gives a downstream speed of 343.072Mbps combined or 42.884Mbps per channel. So from what I can tell the only benefit an 8x4 modem can offer is with internet speeds faster then 171Mbps which can be pretty expensive. I'm sure that others will dispute this. :smileywink:

 

I too use a 6121 and can tell you that there is a reason why its one of the most popular modems sold to date, its rock solid and works great.

Connection Expert
EG
Posts: 40,224
Registered: ‎12-24-2003

Re: Motorola SB6121 upstream power level and modem reboots

[ Edited ]

Nevermind.. Not worth feeding......

Contributor
ezhilk
Posts: 10
Registered: ‎07-24-2012

Re: Motorola SB6121 upstream power level and modem reboots

[ Edited ]

Well, what do you know. My modem has been holding steady for the last 3 days without any dropped connections. I checked the signals and found the upstream power levels had come down t0 around 45dbmv and my downstream power levels had gone up 6dbmv (from around 0~1 dbmv).  I am not sure how, but I did run into another tech who was working on a similar issue for a neighbour in the same building,  maybe they fixed something at the tap.

 

But whatever it maybe, my modem troubles seem to have been resolved at least for now. I am not sure how the SB6121 would've performed but after the initial hiccups, the 5341Jseems to be solid. Thanks for the great suggestion EG :smileyhappy:. I will post again in a week if I see any further issues with the modem (keeping my fingers crossed!)

Contributor
ezhilk
Posts: 10
Registered: ‎07-24-2012

Re: Motorola SB6121 upstream power level and modem reboots

Thanks MikeWolf. I do think the line coming into my apartment could be bad, given that a tech I ran into the other day told me they were receiving quite a few calls from my building and he was suspecting the line too. But the 5341J has been holding up for the last couple of days without any disconnects.I cancelled the tech visit scheduled for today to see how the modem performs over the next week or so, hopefully it continues to do so.

Connection Expert
EG
Posts: 40,224
Registered: ‎12-24-2003

Re: Motorola SB6121 upstream power level and modem reboots

Happy surfing ! :smileyhappy:

Recognized Contributor
MikeWolf
Posts: 581
Registered: ‎10-11-2011

Re: Motorola SB6121 upstream power level and modem reboots

awesome!! glad to hear its working :smileyhappy: for some reason I thought you were having problems while using the 6121 lol.  let us know if something changes :smileyhappy:

Connection Expert
EG
Posts: 40,224
Registered: ‎12-24-2003