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sb6120grief

@distributel.net

SB6120 needs cold boot after Internet down

The problem I am getting is giving me grief.
Whenever Internet goes down, it remain down until I disconnect everything from the cable modem and the power supply to reboot it to get the service back on, simply restarting from the web interface won't work. I will have to cold boot the modem at least 10 times a day which is not funny at all. Sometimes rebooting the modem won't bring the Internet back in service, in such case, I know the Internet is down. I suspect and believe the cable service is not stable and the bigger problem is my modem doesn't wake up after the service is back on.
I'm using Surfboard 6120 and the router is Asus WL-502GU running tomato. Surfboard plugs into the UPS if that matters.
Can someone please help me out? I have my router for awhile, so I don't believe the culprit is the router.

Firmware Name: SB_KOMODO-1.0.6.1-SCM00-NOSH
Boot Version: PSPU-Boot 1.0.0.4m1
Hardware Version: 3.0
Firmware Build Time: May 12 2011 15:15:14

The log shows many of the following and what are they?

6-Notice Cable Modem Reboot due to T4 timeout
3-Critical R07.0 Unicast Ranging Received Abort Response - initializing MAC
5-Warning Z00.0 MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=
5-Warning U102.0 TCS Partial Service;CM-MAC=
3-Critical R07.0 Unicast Ranging Received Abort Response - initializing MAC;Jan 21 2013 06:03:25


NetFixer
Freedom is NOT Free
Premium
join:2004-06-24
The Boro
Reviews:
·Cingular Wireless
·Comcast Business..
·Vonage
said by sb6120grief :

The problem I am getting is giving me grief.
Whenever Internet goes down, it remain down until I disconnect everything from the cable modem and the power supply to reboot it to get the service back on, simply restarting from the web interface won't work. I will have to cold boot the modem at least 10 times a day which is not funny at all. Sometimes rebooting the modem won't bring the Internet back in service, in such case, I know the Internet is down. I suspect and believe the cable service is not stable and the bigger problem is my modem doesn't wake up after the service is back on.
I'm using Surfboard 6120 and the router is Asus WL-502GU running tomato. Surfboard plugs into the UPS if that matters.
Can someone please help me out? I have my router for awhile, so I don't believe the culprit is the router.

Firmware Name: SB_KOMODO-1.0.6.1-SCM00-NOSH
Boot Version: PSPU-Boot 1.0.0.4m1
Hardware Version: 3.0
Firmware Build Time: May 12 2011 15:15:14

The log shows many of the following and what are they?

6-Notice Cable Modem Reboot due to T4 timeout
3-Critical R07.0 Unicast Ranging Received Abort Response - initializing MAC
5-Warning Z00.0 MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=
5-Warning U102.0 TCS Partial Service;CM-MAC=
3-Critical R07.0 Unicast Ranging Received Abort Response - initializing MAC;Jan 21 2013 06:03:25

Apparently your ISP does not keep up with firmware updates; the current firmware version for your modem is:

Firmware Name: SB_KOMODO-1.0.6.8-SCM01-NOSH
Firmware Build Time: Aug 30 2012 15:35:46

The most critical of the log entries you show is "Notice Cable Modem Reboot due to T4 timeout", and that usually is caused by the upstream signal being so far out of specs that the modem reboots to try to get a better sync.

Check your signal levels and report what you see. My guess is that your signals are so far out of specs that when the connection drops, the modem is not always able to resync.

The signal levels shown below (from my SB6121) show mid range values:




Downstream SNR values below ~33dB will be problematic, as will downstream power levels outside +- 8dBmv. If your upstream power levels are at or above 50dBmv, expect more of the T4 timeout reboots.
--
A well-regulated militia, being necessary to the security of a free State, the right of the people to keep and bear arms shall not be infringed.

When governments fear people, there is liberty. When the people fear the government, there is tyranny.


sb6120grief

@distributel.net
Followup... Service just went down and I wrote down some numbers. It came back by itself without rebooting this time.

Downstream SNR, 36dB across the board
Downstream Power levels, -4dBmV,-5dBmV,-4dBmV,-4dBmV
Upstream Power Levels, 0dBmV, 0dBmV,0dBmV, 51dBmV

So, the Downstream SNR looks ok, but the power levels are not. So as the upstream power levels, why 0?

Thanks.


NetFixer
Freedom is NOT Free
Premium
join:2004-06-24
The Boro
Reviews:
·Cingular Wireless
·Comcast Business..
·Vonage
said by sb6120grief :

Followup... Service just went down and I wrote down some numbers. It came back by itself without rebooting this time.

Downstream SNR, 36dB across the board
Downstream Power levels, -4dBmV,-5dBmV,-4dBmV,-4dBmV
Upstream Power Levels, 0dBmV, 0dBmV,0dBmV, 51dBmV

So, the Downstream SNR looks ok, but the power levels are not. So as the upstream power levels, why 0?

Thanks.

Your downstream power levels are within specs, but the 51dBmV is at the edge of useability for DOCSIS 3 (especially if your ISP has started using upstream bonding). At one point, I had upstream power levels in the ~50dBmv range, and I would get random disconnects while the modem rebooted to try to get a better connection. If my upstream level exceeded 52dBmv, the connection was essentially unusable due to the constant rebooting of the modem.

Check all of your coax connections for proper tightness and no corrosion. Tightening loose connections and replacing corroded ones might fix your problems. Replacing older style crimp connectors with better quality compression connectors might also help. The same applies to outside connections that your ISP would have to fix.

And speaking of upstream bonding, those 0dBmV upstream power levels are probably for un-bonded (or non-existent) upstream channels. My SB6121 doesn't bother to show channels that are not being used, but that may be showing on your modem's status page because of the older firmware.
--
A well-regulated militia, being necessary to the security of a free State, the right of the people to keep and bear arms shall not be infringed.

When governments fear people, there is liberty. When the people fear the government, there is tyranny.


sb6120grief

@distributel.net
The coax cable is good and shows no corrosion, pretty new too. Not sure about the outside cable. It seems like the down time has something to do with the upstream power level, when 3 channels have 51 and 1 has 0 dBmV, the modem requires unplugging.

Can I upgrade the firmware? What's the latest version? Is there anything else I can do? Thank you.


NetFixer
Freedom is NOT Free
Premium
join:2004-06-24
The Boro
Reviews:
·Cingular Wireless
·Comcast Business..
·Vonage
said by sb6120grief :

The coax cable is good and shows no corrosion, pretty new too. Not sure about the outside cable. It seems like the down time has something to do with the upstream power level, when 3 channels have 51 and 1 has 0 dBmV, the modem requires unplugging.

Can I upgrade the firmware? What's the latest version? Is there anything else I can do? Thank you.

Comcast only supports three upstream bonded channels, so having three active channels @~46dBmv and one unused channel (which by default would be 0dBmv) is normal for me. But again, your ~51dBmv levels are at the edge of useability on a DOCSIS3 bonded channel environment. That high level combined with your older firmware is what is likely causing your problems.

The is nothing you can do about upgrading your SB6120 firmware except to bug your ISP to upgrade it. There is no way to upgrade it yourself unless you disassemble your modem and add a jtag interface to get low level control; and even then you would have these barriers:

1. You would have to obtain the new firmware (and Motorola only supplies it to ISPs)
2. Most ISPs will overwrite any firmware that they don't officially support with their own version as soon as the modem syncs to their network.

I already posted the latest firmware version in a previous post in this thread, but that won't help you unless your ISP is willing to provide it. FWIW, the main advantage in the latest firmware release is that the SB612x modems with the new firmware will simple drop a problematic upstream channel and continue without it; older firmware versions would either lockup or reboot when an upstream channel became unusable.

If you continue to have problems, you need to convince your ISP to find a way to lower your upstream power levels to below 50dBmv. If you own the SB6120, that may be a futile effort since most ISPs tend to automatically blame customer owned equipment before even thinking about troubleshooting a connection problem.
--
A well-regulated militia, being necessary to the security of a free State, the right of the people to keep and bear arms shall not be infringed.

When governments fear people, there is liberty. When the people fear the government, there is tyranny.


sb6120grief

@distributel.net
Alright, Thank you and appreciate your help.