11-30-2021 03:21 PM
My house had been having intermittent internet issues where it would disconnect completely (even to devices connected by ethernet) and would come back a short time later. After this had gone on for around a day, I called tech support, who told me that there was lots of packet loss on my network and sent a tech. I am decently technical and saw that around this time the CM error codewords were ridiculously high on all channels.
The tech came a few days later and told me that the line to the house is fine and all the coax connections are good. He removed some old splitters that he said might cause packet loss. He wanted to replace the modem (ignite XB6) but said that there was some backend issue that wouldn't allow him to provision a new one. He said to monitor the connection for a few days and if it was still bad to get tech support to issue a swap.
Since the tech came the internet at the house has had no problems, but I am wary that it might cut out at any moment. Hopefully @Datalink and/or @-G- could help me out determining if I should get a swap or not. See the upstream/downstream channel tables and the CM error codeword tables below, system uptime approx. 1 day 6 hours at the time of posting.
The CM error codeword table shows a lot of uncorrectables, but it's less than 0.5% of all codewords, is this ok? I've read that these numbers should be as close to 0 as possible.
IndexLock StatusFrequencySNRPower LevelModulation
Downstream | Channel Bonding Value | |||||||||||||||||||||||||||||||
12 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 |
Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked | Locked |
621 MHz | 279 MHz | 849 MHz | 855 MHz | 861 MHz | 579 MHz | 585 MHz | 591 MHz | 597 MHz | 603 MHz | 609 MHz | 615 MHz | 633 MHz | 639 MHz | 645 MHz | 651 MHz | 657 MHz | 663 MHz | 669 MHz | 675 MHz | 681 MHz | 687 MHz | 693 MHz | 699 MHz | 705 MHz | 711 MHz | 717 MHz | 723 MHz | 825 MHz | 831 MHz | 837 MHz | 843 MHz | 350000000 |
41.8 dB | 38.2 dB | 41.0 dB | 41.1 dB | 41.2 dB | 39.9 dB | 40.1 dB | 40.5 dB | 40.6 dB | 40.6 dB | 41.0 dB | 41.0 dB | 41.9 dB | 42.1 dB | 41.8 dB | 41.9 dB | 42.0 dB | 41.9 dB | 42.1 dB | 41.8 dB | 42.2 dB | 42.0 dB | 42.1 dB | 42.1 dB | 42.0 dB | 42.2 dB | 42.0 dB | 41.9 dB | 41.3 dB | 41.3 dB | 41.2 dB | 41.1 dB | 37.6 dB |
3.0 dBmV | -4.3 dBmV | 4.8 dBmV | 4.7 dBmV | 4.3 dBmV | 0.6 dBmV | 0.4 dBmV | 0.4 dBmV | 0.3 dBmV | 0.7 dBmV | 1.5 dBmV | 2.1 dBmV | 3.9 dBmV | 4.1 dBmV | 3.9 dBmV | 4.1 dBmV | 4.0 dBmV | 4.1 dBmV | 4.5 dBmV | 4.5 dBmV | 4.6 dBmV | 4.8 dBmV | 4.6 dBmV | 4.8 dBmV | 4.9 dBmV | 4.7 dBmV | 4.8 dBmV | 4.5 dBmV | 5.9 dBmV | 5.6 dBmV | 5.4 dBmV | 5.1 dBmV | -1.0 dBmV |
256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | 256 QAM | OFDM |
IndexLock StatusFrequencySymbol RatePower LevelModulationChannel Type
Upstream | Channel Bonding Value | |||
1 | 2 | 3 | 4 | 5 |
Locked | Locked | Locked | Locked | Locked |
21 MHz | 25 MHz | 32 MHz | 38 MHz | 4 MHz |
2560 | 5120 | 5120 | 5120 | 0 |
43.8 dBmV | 44.8 dBmV | 45.8 dBmV | 45.5 dBmV | 435000.0 dBmV |
QAM | QAM | QAM | QAM | OFDMA |
TDMA_AND_ATDMA | ATDMA | ATDMA | ATDMA | TDMA |
CM Error Codewords | ||||||||||||||||||||||||||||||||
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 |
3820886726 | 412571606 | 466903338 | 466917657 | 466928141 | 466970520 | 466978334 | 466985940 | 466995080 | 467002151 | 467005939 | 467011651 | 467015986 | 467027183 | 467034823 | 467041288 | 467049523 | 467051974 | 467061292 | 467071385 | 467081558 | 467086614 | 467093591 | 467078060 | 467073057 | 467105250 | 467112590 | 467121535 | 467071811 | 467077640 | 467073976 | 467076220 | 3820886726 |
3614814946 | 2019052 | 54129 | 53367 | 51990 | 34823 | 33586 | 33412 | 33018 | 32565 | 32614 | 32217 | 32120 | 31067 | 29145 | 29557 | 28956 | 30505 | 29604 | 28775 | 26948 | 27067 | 26601 | 33741 | 36986 | 26948 | 26981 | 27131 | 50131 | 51777 | 54098 | 54505 | 3614814946 |
6116517 | 858821 | 70653 | 65919 | 63796 | 46403 | 46756 | 45027 | 44756 | 44563 | 44664 | 44342 | 43931 | 42375 | 40354 | 40975 | 40128 | 42013 | 40757 | 38237 | 38202 | 37229 | 38039 | 46397 | 55867 | 39931 | 38414 | 38360 | 68292 | 69154 | 72089 | 71564 | 6116517 |
12-01-2021 12:25 AM
@mdfriendly I'm not entirely sure what to make of these stats because they look odd.
The Downstream SNR and Power Levels are within spec but looking across all channels, the power levels range from -4.3 dBmV to 5.9 dBmV.
Your modem is also outputting a higher than normal power level upstream, something that I would not expect to see given that your modem is seeing strong downstream power levels... unless perhaps they have an amplifier installed to boost the signal to your home. You also have an upstream OFDM channel enabled with a totally bogus power level displayed.
As for your error stats, your Uncorrectable Codewords count ideally should be zero across the board, and your downstream OFDM channel definitely should be close to zero, not 6116517. Your modem should be using the downstream OFDM channel but I don't know at what point (or if) it would switch from DOCSIS 3.1 to D3.0 mode.
The other thing I don't understand is why the error count is so high, across all channels, yet your SNR stats don't reflect a lot of noise. Do these error counts ever remain stable or are they constantly increasing?
I would send a private message to @CommunityHelps and them to check the stats on your local node.
I can't tell you whether your modem needs to be replaced or not, or whether there are signal problems in your area. Rogers can validate everything by looking at the local node and by looking at your neighbours' stats. Without information as to what the Rogers techs and maintenance crews have been doing in your area to try to fix your issues, I cannot provide you with an informed opinion on what the next steps should be.
12-01-2021 12:54 AM - edited 12-01-2021 12:56 AM
Yup, its a mystery alright. The downstream Docsis 3.0 levels have a wide range, but, taken individually, their in spec. I'd like to see no more than a 2 to 3 dB range, centered around 0 dBmV, personal opinion of course. The signal to noise ratios are really good, so that doesn't jive with the high uncorrected code words. So, one of the problems here, as @-G- indicated, we don't know if the modem is using the OFDM downstream channel only, or if its running in a mixed mode, using both Docsis 3.0 QAM channels and Docsis 3.0 OFDM channel sub-carriers. We don't have any visibility into the sub-carrier signal levels and signal to noise ratios, so, you would have to send a message to @CommunityHelps to have one of the moderators check the OFDM MIBS. Tech support doesn't have access to that data, but the moderators should. If that check comes back ok, then there's another issue afoot somewhere else. That codeword error count would be looking at the total sum of codewords as transmitted to the modem from the Cable Modem Termination System. There are multiple components along the way that could be causing a problem, with the modem being the last device in the chain. I don't believe that you have a modem problem. Historically, the modem failure rate is very low, but, for whatever reason, tech support and the field techs seem to push modem replacements as the cure-all.
So, questions of the day:
1. Is your external cabling overhead or underground? I'm
2. Do you know when that cabling was changed or installed?
3. Did the tech remove all of the splitters, or, is there still one or two splitters still present in the junction between the external cable and the internal cable? A remaining splitter would explain the elevated upstream levels.
I think the techs should be looking at your neighbours data to see if the situation is a "one of", as in yours, or if the same problem can be seen with the immediate neighbours modems as well, which points to the local tap or further upstream. I don't think there's any point in doing anything without checking that data first. If this is your problem only, then it points to a nearby noise source, despite the signal to noise ratios, to a degraded cable, and lastly the remote possibility of a failing modem (which I don't believe, but its possible).
fwiw, my two cents.....
12-01-2021 10:01 AM
The unerrored count on channels 1 and 33 stayed consistent at 6116517 for around a day and the total is now 7983787. Thanks for the info and advice, I'll be sure to send the mods a message and see if they can look into it.
12-01-2021 10:06 AM
As per your questions, the cables running to the house are buried. The internal cables were redone when the house was renovated around 2 years ago, but I suspect the external cables are at least 5 years old. As far as I'm aware, the tech removed all the splitters, he even said that someone removed a splitter from the area box which might have improved things.
There have been a bunch of area outages (according to the Rogers chatbot at least) over the past month which might indicate that it's not just me with this problem. Thanks for letting me know about the modem fail rate, I used to work in a Fido store and we just told everyone to get a new one, guess it's just the quick fix.
I'll be sure to reach out to the mods to check on the area data, thanks for your help!