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mpgstuff
join:2003-07-07
Kenosha, WI

mpgstuff to hobgoblin

Member

to hobgoblin

Re: [TWC] Cable Modem Resets

Received the SB6141 this afternoon. Called support to get it provisioned, National Helpdesk tech said they couldn't do it so she transferred me to Tier 3. Was up and running in about 20 minutes. Tier 3 guy said my signal levels looked perfect.

10 minutes after hanging up, T3 timeouts and connection dropped. Hoped that it was a fluke. 30 minutes later, same thing connection dropped.
Dec 21 2012 15:36:25 3-Critical C206.0 DCC aborted unable to communicate on new upstream channel;
Dec 21 2012 15:36:25 3-Critical R08.0 16 consecutive T3 timeouts while trying to range on upstream channel 3
Dec 21 2012 15:36:24 3-Critical R03.0 Ranging Request Retries exhausted;
Dec 21 2012 15:36:18 3-Critical R02.0 No Ranging Response received - T3 time-out;

Seems the same issue, can't acquire upstream, T3 timeouts.

Just got off the phone again and have a technician scheduled to come out, next available day is the 29th. I have a feeling this will be something that will never be fixed.

thomasr
join:2010-01-21
Winston Salem, NC

thomasr

Member

Your feeling is probably correct. I have seen these errors for years, using multiple modems (Ambit, Arris, RCA and Motorola) at multiple locations. I dug up a link I referenced a year and a half ago that kind of explains possible causes of these errors.

T3 and T4 Timeouts
I wanted to close this topic with a discussion on T3 and T4 timeouts as I have received many questions on “what causes T3 and T4 timeouts?” Fundamentally, a T3 timeout occurs when the cable modem fails to receive a RNG-RSP from the CMTS within 200 msec (after sending a RNG-REQ). A T4 timeout occurs when a cable modem fails to receive a RNG-REQ transmit grant MAP from the CMTS within 35 sec on the downstream channel (after receiving the previous RNG-RSP). There are number of reasons that these could occur and I will list a couple below for each and help guide you the root cause, but understand this is not and exhaustive list.

T3 Timeout No RNG-RSP in 200 msec – Typically an Upstream Problem

Most likely cause is upstream impairments preventing the RNG-REQ from reaching the CMTS, therefore the CMTS never transmits a RNG-RSP

May occur because the RNG-REQs from multiple cable modems collided, again the CMTS does not receive the RNG-REQ (now from multiple modems) and fails to process multiple RNG-RSP messages resulting in multiple T3 timeouts

CMTS over-utilization – unable to process RNG-REQ and/or RNG-RSP within T3 time frame (200 msec)

Can also be a downstream problem due to plant impairments – i.e. RNG-RSP is transmitted, but corrupted in route and the cable modem never receives the message

Look for low MER at the cable modem

T4 Timeout No RNG-REQ Grant MAP Received by Cable Modem in 35 sec – Typically a Downstream Problem

T4 timeouts can usually be identified with downstream impairments causing the cable modem to miss receiving the RNG-REQ grant MAP transmitted to it

If T4 errors are impacting many modems off of a common leg, trouble shoot that leg

If T4 errors are just associated with one modem, look for low MER/level at that modem

T4 timeouts can also be associated with a CMTS that has extremely high utilization i.e. >95% depending on the vendor and firmware version

Rule of thumb for CMTS utilization is 80% to allow for peak usage periods

It is highly unlikely that T4 timeouts are associated with any upstream impairments

»volpefirm.com/blog/docsi ··· tenance/

I register multiple T3 or T4 errors and disconnects daily at my current location. Just something I've gotten used to...

Here's my current specs:

Model Name: SB6141
Vendor Name: Motorola
Firmware Name: SB_KOMODO-1.0.6.3-SCM03-NOSH
Boot Version: PSPU-Boot(25CLK) 1.0.12.
Hardware Version: 7.0
Serial Number: ************************
Firmware Build Time: Aug 18 2011 10:27:53

Downstream Bonding Channel Value
Channel ID 68 65 66 67
Frequency 561000000 Hz 543000000 Hz 549000000 Hz 555000000 Hz
Signal to Noise Ratio 38 dB 37 dB 38 dB 38 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
0 dBmV 0 dBmV 0 dBmV 0 dBmV
Upstream Bonding Channel Value
Channel ID 4
Frequency 34600000 Hz
Ranging Service ID 72
Symbol Rate 2.560 Msym/sec
Power Level 48 dBmV
Upstream Modulation [5] 16QAM

Ranging Status Success
Signal Stats (Codewords) Bonding Channel Value
Channel ID 68 65 66 67
Total Unerrored Codewords 652831645 652839864 652847258 652856236
Total Correctable Codewords 14 0 0 1
Total Uncorrectable Codewords 646 575 1363 570
cramer
Premium Member
join:2007-04-10
Raleigh, NC
Westell 6100
Cisco PIX 501

cramer to mpgstuff

Premium Member

to mpgstuff

Dec 21 2012 15:36:25 3-Critical C206.0 DCC aborted unable to communicate on new upstream channel

DING DING DING

Your modem was commanded to move to a channel that doesn't work (filtered, noisy, doesn't exist on your node -- happens more often than you'd think)
mpgstuff
join:2003-07-07
Kenosha, WI

1 edit

mpgstuff

Member

cramer, do you think this is this something a Technician can fix, or at least communicate up the chain to get fixed?

The technician visit got bumped up to tomorrow instead of a week from today. I plan to just tell him what I've experienced over the past 2 months. I can show him all the modem logs, basically every time it would reset I would copy and paste all the logs into a spreadsheet. Not sure if that will be worthy evidence or not.

I've been on the SB6141 for approximately 16 hours. Looking at my saved logs it seems to happen the most between the hours of 2-9PM, but that's also more likely the time a user would be on and notice something so I wouldn't suggest its time bound. Below are all the logs so far on the SB6141. I will see what happens throughout today.

Dec 22 2012 06:47:48 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
Dec 21 2012 16:28:53 5-Warning Z00.0 MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
Dec 21 2012 16:28:46 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
Dec 21 2012 16:28:19 3-Critical C206.0 DCC aborted unable to communicate on new upstream channel;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
Dec 21 2012 16:28:19 3-Critical R08.0 16 consecutive T3 timeouts while trying to range on upstream channel 4;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
Dec 21 2012 16:28:18 3-Critical R03.0 Ranging Request Retries exhausted;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
Dec 21 2012 16:28:12 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
Dec 21 2012 16:07:39 5-Warning Z00.0 MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
Dec 21 2012 16:07:21 3-Critical C206.0 DCC aborted unable to communicate on new upstream channel;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
Dec 21 2012 16:07:21 3-Critical R08.0 16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
Dec 21 2012 16:07:21 3-Critical R03.0 Ranging Request Retries exhausted;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
Dec 21 2012 16:07:19 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
Dec 21 2012 15:44:37 5-Warning Z00.0 MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
Jan 01 1970 00:00:14 6-Notice Cable Modem Reboot from SNMP ;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.0;
Dec 21 2012 15:36:41 5-Warning Z00.0 MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
Dec 21 2012 15:36:25 3-Critical C206.0 DCC aborted unable to communicate on new upstream channel;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
Dec 21 2012 15:36:25 3-Critical R08.0 16 consecutive T3 timeouts while trying to range on upstream channel 3;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
Dec 21 2012 15:36:24 3-Critical R03.0 Ranging Request Retries exhausted;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
Dec 21 2012 15:36:18 3-Critical R02.0 No Ranging Response received - T3 time-out;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;
Dec 21 2012 15:03:03 5-Warning Z00.0 MIMO Event MIMO: Stored MIMO=-1 post cfg file MIMO=-1;CM-MAC=xx:xx:xx:xx:xx:xx;CMTS-MAC=xx:xx:xx:xx:xx:xx;CM-QOS=1.1;CM-VER=3.0;

Downstream Bonding Channel Value
Channel ID 9 10 11 12
Frequency 693000000 Hz 699000000 Hz 705000000 Hz 711000000 Hz
Signal to Noise Ratio 37 dB 38 dB 37 dB 37 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
-3 dBmV -3 dBmV -3 dBmV -3 dBmV

Upstream Bonding Channel Value
Channel ID 2
Frequency 21000000 Hz
Ranging Service ID 4889
Symbol Rate 2.560 Msym/sec
Power Level 47 dBmV
Upstream Modulation [6] 16QAM
[2] 64QAM

Ranging Status Success

Signal Stats (Codewords) Bonding Channel Value
Channel ID 9 10 11 12
Total Unerrored Codewords 2793292415 2792614872 2792632754 2792640059
Total Correctable Codewords 2623 185 0 2
Total Uncorrectable Codewords 1319 1413 522 1392

djrobx
Premium Member
join:2000-05-31
Reno, NV

djrobx

Premium Member

it seems to happen the most between the hours of 2-9PM, but that's also more likely the time a user would be on and notice something so I wouldn't suggest its time bound.

Channel change requests happen because the CMTS is trying to balance the load. This activity is most likely to happen during peak hours.

If not fixed, the problems will likely stop once TWC figures out how to get the upstreams bonded, removing the need for channel changes on bonded modems.
mpgstuff
join:2003-07-07
Kenosha, WI

mpgstuff

Member

Thanks for the response. I will see what the technician says tomorrow. I'm not sure what he/she will want to look at inside the house (or outside for that matter). Inside, nothing has changed in the 10 years we've had the service. I looked at the coax and splitters and everything is tight and "appears" fine inside.
I can show them the cable modem logs and the new cable modem, the is about it for inside.

As a side note, I noticed in the SB6141 logs that my most recent entry (a few posts up) was timestamped Dec 22 2012 06:47:48. Now when I look at it, it is the same error message (T3 Time-out) but the time-stamp is Dec 22 2012 10:18:52 and the 06:47:48 entry is no longer there. Does the SB6141 do some sort of in-place log replacement/consolidation?

motorola870
join:2008-12-07
Arlington, TX

1 edit

motorola870 to djrobx

Member

to djrobx
not necessarily going to stop load balancing I had my modem reset the other night and it took the primary downstream for 783MHz to 807MHz which is channel 5 all while still bonding 6 downstreams and 4 upstreams!

Startup Procedure
Procedure Status Comment
Acquire Downstream Channel Locked
Connectivity State OK Operational
Boot State OK Operational
Configuration File
Security Enabled BPI+

Downstream Bonded Channels
Channel Lock Status Modulation Channel ID Frequency Power SNR Correctables Uncorrectables
1 Locked QAM256 5 807000000 Hz -5.9 dBmV 35.4 dB 1857 0
2 Locked QAM256 1 783000000 Hz -4.3 dBmV 37.2 dB 145 0
3 Locked QAM256 2 789000000 Hz -4.5 dBmV 37.0 dB 200 0
4 Locked QAM256 3 795000000 Hz -5.1 dBmV 36.1 dB 522 0
5 Locked QAM256 4 801000000 Hz -5.1 dBmV 36.2 dB 705 0
6 Locked QAM256 6 813000000 Hz -5.5 dBmV 36.2 dB 1011 29
7 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0
8 Not Locked Unknown 0 0 Hz 0.0 dBmV 0.0 dB 0 0

Upstream Bonded Channels
Channel Lock Status US Channel Type Channel ID Symbol Rate Frequency Power
1 Locked TDMA and ATDMA 10 2560 Ksym/sec 33000000 Hz 42.0 dBmV
2 Locked TDMA and ATDMA 9 2560 Ksym/sec 36500000 Hz 42.0 dBmV
3 Locked TDMA and ATDMA 11 2560 Ksym/sec 29500000 Hz 42.0 dBmV
4 Locked TDMA and ATDMA 12 2560 Ksym/sec 24500000 Hz 42.0 dBmV

I would think that the correctables should be expected in my area as TWC is using the same bands as wireless providers do so there could be a small amount of noise getting in from the node to my house I believe this set up is better than having my downstreams in the 99MHz to 123MHz like some areas do in Ohio on TWC.

I am actually surprised that have 4 upstreams with QAM64 as when QAM64 first rolled out at the beginning of 2011 in my area I was struggling to keep QAM64 on two of the 4 upstreams and sometimes 3 of them as my modem would keep alternating. Right now these basically are equivalent to two QAM64 6.4MHz wide channels on the downstream I have a feeling that we will have them respaced in early 2013 to maximize the upstream capacity and two of them will go 3.2MHz wide QAM16 and the other two will go 6.4MHz wide QAM64.