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gregftluad

join:2010-03-20
Fort Lauderdale, FL

1 edit

Unicast Maintenance Ranging Attempted Issues

I've noticed several times over the last few weeks in the logs on my Motorola SB6120 Docsis 3.0 modem that after an entry that says "Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-". Then I'll get a T4 timeout and my modem reboots. It just happened and according to my logs it happened at 5am this morning too. I've seen that maintenance ranging attempted with no response almost everyday on the logs but rarely does it make the modem reboot but it's been happening alot lately. Anyone else seeing this? Any ideas what is going on?

Here are signals and logs

Downstream Bonding Channel Value
Channel ID 3 1 2 4
Frequency 693000000 Hz 705000000 Hz 699000000 Hz 687000000 Hz
Signal to Noise Ratio 37 dB 38 dB 37 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
6 dBmV 6 dBmV 5 dBmV 6 dBmV

Upstream Bonding Channel Value
Channel ID 8
Frequency 36400000 Hz
Ranging Service ID 3326
Symbol Rate 5.120 Msym/sec
Power Level 47 dBmV
Upstream Modulation [3] QPSK
[3] 64QAM

Ranging Status Success

Time Priority Code Message
Jan 01 1970 00:00:38 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:00:12 6-Notice Cable Modem Reboot due to T4 timeout ;CM-QOS=1.1;CM-VER=3.0;
Nov 24 2010 17:53:00 3-Critical R06.0 Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-;CM-QOS=1.1;CM-VER=3.0;
Nov 24 2010 17:53:00 3-Critical R03.0 Ranging Request Retries exhausted;CM-QOS=1.1;CM-VER=3.0;
Nov 24 2010 17:52:59 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:00:12 6-Notice Cable Modem Reboot from GUI/Configuration page ;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:00:36 3-Critical R02.0 No Ranging Response received - T3 time-out;CMTS-;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:00:12 6-Notice Cable Modem Reboot due to T4 timeout ;CMTS-;CM-QOS=1.1;CM-VER=3.0;
Nov 24 2010 05:47:58 3-Critical R06.0 Unicast Maintenance Ranging attempted - No response - Retries exhausted;CM-QOS=1.1;CM-VER=3.0;
Nov 24 2010 05:47:58 3-Critical R03.0 Ranging Request Retries exhausted;CM-QOS=1.1;CM-VER=3.0;
Nov 24 2010 05:47:56 3-Critical R02.0 No Ranging Response received - T3 time-out;CMTS-;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:00:05 5-Warning D04.1 ToD request sent - No Response received;;CMTS-;CM-QOS=1.1;CM-VER=3.0;
Nov 21 2010 01:27:37 3-Critical R02.0 No Ranging Response received - T3 time-out;;CMTS;CM-QOS=1.1;CM-VER=3.0;



gar187er
I do this for a living

join:2006-06-24
Dover, DE
kudos:4

could be scheduled maintenance , could be noise....
--
I'm better than you!



Tordek
Make the outages go away
Premium
join:2009-09-07
Great White
kudos:2

I smell uSNR....



EG
The wings of love
Premium
join:2006-11-18
Union, NJ
kudos:10

So if it is a "uSNR" issue, they can call in and ask what the figure is. It should be at least 29-30dB and the higher the better.


gregftluad

join:2010-03-20
Fort Lauderdale, FL

u mean upstream SNR? i wonder why our modem config page doesnt show upstream SNR.......and only down.



Mike_

join:2003-06-24
Fort Lauderdale, FL
reply to gregftluad

I had these errors quite a few weeks ago and also init errors that would cause a reboot at all sorts of times/intervals of the day. eChatting in of course got me no where since they have no clue what they are. Also note that signals were/are fine and the building I am in is only months old so coax is excellent quality.

Anyway, over a few days time these errors stopped occurring and have not had them since. So its either physical issues somewhere down the pipe, system issues, or maintenance/upgrades.
--
If it ain't broke, don't fix it. Unless you know what you're doing.


gregftluad

join:2010-03-20
Fort Lauderdale, FL
reply to gregftluad

i called comcast they told me my uSNR is 35.1dB (which they said is perfectly fine)



EG
The wings of love
Premium
join:2006-11-18
Union, NJ
kudos:10

2 edits
reply to gregftluad

said by gregftluad:

i wonder why our modem config page doesnt show upstream SNR.......and only down.

It can't. It's not physically possible. It must be remotely read from their end and at the CMTS level because a modem can't read what is going on on the other end that it is connected to. Are you sure that the rep gave you the uSNR figure because it sounds typical of a downstream SNR figure as read by the modem which they also see ? Many phone reps really don't know the difference. The training and knowledge of a phone rep can typically leave something to be desired... Maybe you should get a 'second opinion' ?


Tordek
Make the outages go away
Premium
join:2009-09-07
Great White
kudos:2
reply to gregftluad

Yea it's upstream SNR.

The reason why it's not shown on the modem page is that it is read off of the CMTS and thats TMO for your average customer.

35.X seems awfully high for an uSNR... either your plant is frickin' tight, or they are giving you the dSNR instead lol

If it is the uSNR it still don't elminate it, as where the issue is not happening now it could be an intermittent noise source (Bain of my existence...)
--
If Tier II had there way.... a full node outage would be 3 people....


gregftluad

join:2010-03-20
Fort Lauderdale, FL

4 edits

According to EG he said the uSNR should be AT LEAST 29-30db and the higher the better. Mine is 35.1. And yes I'm sure he gave me the uSNR b/c he gave me both SNR's for down and up. Plus my down SNR is always around 37-38. Just called again and asked for both down and up figures. Down was what i was looking at on my 192.168.100.1 page he said uSNR is 33.9.

What do u mean my "plant might be tight"?



Tordek
Make the outages go away
Premium
join:2009-09-07
Great White
kudos:2

Plant being tight is just our lingo for "No noise getting in" like when you close a bottle tight so nothing gets in or out.

Being on a tight plant is actually a good thing. Usually it means its swept (monitored) hard and frequently to make sure things are all falling into place as they should.

Here, our maintenance techs (speaking from experience) are paged the second the uSNR drops below 33. The reason for this is we are starting to run high QAM's on the return path and they are a helluva lot more prone and picky to noise.

--

It's quite possible it could of been some black-ops maintenance (when no one knows where your to) or you could be experiencing an intermittent noise source. I had one that ruined my life for 2 weeks only to end up finding a segment running beneath an ILS branch at the airport was shot :P Only started to light up when the ILS went active :P
--
If Tier II had there way.... a full node outage would be 3 people....


gregftluad

join:2010-03-20
Fort Lauderdale, FL

2 edits

Oh so then a high uSNR (within acceptable ranges like i'm in) dont cause problems......

Still wondering why then after these two unicast maintenance attemps that failed why my modem reboots. Oh well i guess some things will just remain a mystery when it comes to any high speed internet service. Most likely just a glitch or they were working on the system.

I called a 3rd time just to make sure they gave me correct levels so I asked for both down and up SNR. Down was 36.1 and up this time was 33.4. So the techs i'm speaking with obviously know the difference between up and down SNR and they arent just giving me down figures only.