MattChapman
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Periodic connection dropouts

Hi all,

 

I posted a while back when I had some problems with terrible packet loss, and while those problems were resolved by a Ziggo engineer at the wijkcabinet, I am now having issues with periodic connection drops.

 

Here is my connection log:

 

2021-06-15 12:56:31noticeCM-STATUS message sent. Event Type Code: 5; Chan ID: 4 5 6 7 11 12 19 21 23 25 26 27 28 29 30 31 32 ; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 12:56:15noticeCM-STATUS message sent. Event Type Code: 4; Chan ID: 29 30 31 32 ; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: N/A.;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 12:56:02warningMDD message timeout;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 08:14:53noticeDS profile assignment change. DS Chan ID: 32; Previous Profile: ; New Profile: 1 2 3 .;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 08:14:17noticeTLV-11 - unrecognized OID;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 08:14:15errorMissing BP Configuration Setting TLV Type: 17.9;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 08:14:15errorMissing BP Configuration Setting TLV Type: 17.8;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 08:14:15errorMissing BP Configuration Setting TLV Type: 17.7;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 08:14:15errorMissing BP Configuration Setting TLV Type: 17.6;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 08:14:15errorMissing BP Configuration Setting TLV Type: 17.5;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 08:14:15errorMissing BP Configuration Setting TLV Type: 17.4;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 08:14:15errorMissing BP Configuration Setting TLV Type: 17.3;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 08:14:15errorMissing BP Configuration Setting TLV Type: 17.2;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 08:14:15errorMissing BP Configuration Setting TLV Type: 17.1;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
1970-01-01 00:00:30warningDHCP WARNING - Non-critical field invalid in response ;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
1970-01-01 00:00:28noticeHonoring MDD; IP provisioning mode = IPv4
1970-01-01 00:00:21criticalSYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 01:48:43criticalNo Ranging Response received - T3 time-out;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 01:48:19criticalNo Ranging Response received - T3 time-out;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 01:34:17criticalSYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:00:00:00:00:00;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 01:34:13criticalReceived Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 01:34:12criticalSYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 01:34:11criticalReceived Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 01:34:10criticalSYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 01:34:10criticalReceived Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 01:34:10criticalSYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 01:34:09criticalReceived Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 01:34:08criticalSYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 01:34:08criticalReceived Response to Broadcast Maintenance Request, But no Unicast Maintenance opportunities received - T4 time out;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 01:33:56criticalSYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 01:33:51criticalSYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;
2021-06-15 01:33:47critical

SYNC Timing Synchronization failure - Failed to acquire QAM/QPSK symbol timing;;CM-MAC=0c:b9:37:9a:32:bc;CMTS-MAC=00:17:10:93:e1:15;CM-QOS=1.1;CM-VER=3.1;

 

I see multiple sync failures, T3 & T4 timeouts and CM-STATUS messages 4 and 5 (Secondary Channel MDD Recovery and QAM/FEC Lock Recovery respectively). I also have seen messages like "CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW", but those (and others) get wiped on a modem power cycle.

 

Connection stats:

 

CM Downstream Channel Info
ChannelLock StatusChannel TypeChannel IDFrequencyWidthPowerSNRModulation Profile IDCorrectablesUncorrectables
1LockedSC-QAM Downstream3618000000 Hz8000000 Hz11 dBmV40.6 dBQAM25621131
2LockedSC-QAM Downstream1602000000 Hz8000000 Hz12.4 dBmV40.8 dBQAM25615246
3LockedSC-QAM Downstream2610000000 Hz8000000 Hz12 dBmV40.9 dBQAM25616436
4LockedSC-QAM Downstream4626000000 Hz8000000 Hz10.6 dBmV40.1 dBQAM25619748
5LockedSC-QAM Downstream5634000000 Hz8000000 Hz10.4 dBmV39.9 dBQAM25619738
6LockedSC-QAM Downstream6642000000 Hz8000000 Hz10.6 dBmV40 dBQAM25618950
7LockedSC-QAM Downstream7650000000 Hz8000000 Hz10.8 dBmV40 dBQAM25618936
8LockedSC-QAM Downstream8658000000 Hz8000000 Hz11.4 dBmV40.5 dBQAM25622275
9LockedSC-QAM Downstream9666000000 Hz8000000 Hz12.1 dBmV40.5 dBQAM25620062
10LockedSC-QAM Downstream10674000000 Hz8000000 Hz12.4 dBmV40.7 dBQAM25618374
11LockedSC-QAM Downstream11682000000 Hz8000000 Hz12 dBmV40.8 dBQAM25618329
12LockedSC-QAM Downstream12690000000 Hz8000000 Hz12 dBmV40.8 dBQAM25618244
13LockedSC-QAM Downstream13698000000 Hz8000000 Hz12.4 dBmV41 dBQAM25621427
14LockedSC-QAM Downstream14706000000 Hz8000000 Hz12 dBmV40.8 dBQAM25614835
15LockedSC-QAM Downstream15714000000 Hz8000000 Hz11.5 dBmV40.6 dBQAM25616148
16LockedSC-QAM Downstream16722000000 Hz8000000 Hz11.4 dBmV40.6 dBQAM25621133
17LockedSC-QAM Downstream17730000000 Hz8000000 Hz11.4 dBmV40.4 dBQAM25622049
18LockedSC-QAM Downstream18738000000 Hz8000000 Hz11.3 dBmV40 dBQAM25627827
19LockedSC-QAM Downstream19746000000 Hz8000000 Hz11.4 dBmV40.1 dBQAM25624223
20LockedSC-QAM Downstream20754000000 Hz8000000 Hz11.2 dBmV40 dBQAM25625259
21LockedSC-QAM Downstream21762000000 Hz8000000 Hz11 dBmV40.1 dBQAM25624532
22LockedSC-QAM Downstream22770000000 Hz8000000 Hz10.5 dBmV40.1 dBQAM25625484
23LockedSC-QAM Downstream23778000000 Hz8000000 Hz10.4 dBmV40.1 dBQAM25623064
24LockedSC-QAM Downstream24786000000 Hz8000000 Hz10.6 dBmV40 dBQAM25625571
25LockedSC-QAM Downstream25794000000 Hz8000000 Hz10.2 dBmV39.8 dBQAM25626648
26LockedSC-QAM Downstream26802000000 Hz8000000 Hz10.3 dBmV39.9 dBQAM25627135
27LockedSC-QAM Downstream27810000000 Hz8000000 Hz10.5 dBmV39.9 dBQAM25628358
28LockedSC-QAM Downstream28818000000 Hz8000000 Hz10.3 dBmV39.9 dBQAM25627662
29LockedSC-QAM Downstream29826000000 Hz8000000 Hz9.5 dBmV39.7 dBQAM25629558
30LockedSC-QAM Downstream30834000000 Hz8000000 Hz8.8 dBmV39.3 dBQAM25630744
31LockedSC-QAM Downstream31842000000 Hz8000000 Hz8.4 dBmV39 dBQAM25632359
32LockedSC-QAM Downstream32850000000 Hz8000000 Hz8.4 dBmV38.9 dBQAM25635063
33LockedOFDM Downstream33883000000 Hz93000 kHz7.6 dBmV38.1 dBOFDM PLC34400

 

 

 

CM Upstream Channel Info
ChannelLock StatusChannel TypeChannel IDFrequencyWidthPowerModulation/Profile ID
1LockedATDMA158800000 Hz6400000 Hz41 dBmV2
2LockedATDMA252000000 Hz6400000 Hz41 dBmV2
3LockedATDMA345200000 Hz6400000 Hz41 dBmV2
4LockedATDMA438400000 Hz6400000 Hz41 dBmV2
5LockedATDMA533200000 Hz3200000 Hz40 dBmV2
6LockedATDMA630000000 Hz3200000 Hz40 dBmV2

 

Error numbers are fairly low, but this is after an uptime of only 5 hours. My understanding is that uncorrectable errors should be 0 across the board, and correctable errors are of no concern.

 

I have tried:

 

  • Rebooting modem
  • Replacing coax cable
  • Removing splitter

All to no effect - it looks to me like I am having interference issues again.

 

Any help would be appreciated! Thanks in advance 🙂

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tobiastheebe
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The current AOP (X10DER) is a special one for cases where the green CAI cable is very short and does not allow for connecting a 'regular' AOP.

 

The splitter (which is only being used as a 4 dB attenuator here) makes the modem vulnerable to external noise and interference due to the unterminated output. You should replace the splitter with a dedicated attenuator, 6 dB should be good. This attenuator can be screwed onto the modem's coax connector directly.

Bekijk in context

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tobiastheebe
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Downstream power levels are quite high, perhaps due to the splitter being removed. The log indicates noise/stability issues in both downstream and upstream, which could be partially related to the uncorrectable errors. Correctable errors and T3 timeouts are acceptable to some extent. Looking at the (un)correctable errors, none of the channels stand out in particular, therefore I don't suspect an interference issue at this time.

 

Could you post one or more pictures of AOP (main socket inside utility closet ('meterkast') or in living room) and cables, plus splitter(s) and signal amplifier, as applicable?

Mariska
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Hi @MattChapman

I'm sorry you're experiencing problems again! Luckily we're here to help. It would be great if you can post the pictures that tobiastheebe asked for so we can hopefully see what's causing the problems. Thanks in advance 🙂 

MattChapman
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Hi @tobiastheebe and @Mariska , thanks for responding!

 

Photo of the AOP:

 

D37E8554-C431-40B6-8D0D-C80CFADFE959.jpeg

the cable connects directly into the Ubee modem:

 

E0B127AD-9284-4161-8117-05D1736B2186.jpeg

No extra splitters or amplifiers involved, which keeps things nice and simple.

 

The AOP has been replaced twice - once by a Ziggo engineer, and then a second time by an engineer from BAM when the previous problem was suspected to be cable damage outside the property.

 

I'm not sure why the photos uploaded sideways, but oh well 😁  Cheers!

tobiastheebe
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The current AOP (X10DER) is a special one for cases where the green CAI cable is very short and does not allow for connecting a 'regular' AOP.

 

The splitter (which is only being used as a 4 dB attenuator here) makes the modem vulnerable to external noise and interference due to the unterminated output. You should replace the splitter with a dedicated attenuator, 6 dB should be good. This attenuator can be screwed onto the modem's coax connector directly.

Bekijk in context

MattChapman
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Hi @tobiastheebe , the AOP makes sense - the green cable comes up the side of my apartment building in some conduit, and then comes straight through my wall and into the connector which is now there. My understanding from the Ziggo and BAM engineers that have been in the past is that there is essentially no slack for them to use. I would love for them to pull a new length of cable, but I get that it isn't the most practical option!

 

I didn't consider that the splitter could pick up interference - I'll for sure pick up an attenuator, from your link it seems they are only a couple of euros.

 

I'll report back once I try that out - I appreciate the advice!

tobiastheebe
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Correct, no cable slack is very frustrating for technicians installing/replacing an AOP. When a new cable is pulled into a property, approximately 1 meter of service loop should be left to allow for retrofitting, this is however a 100% ideal situation that often does not exist. Installing an AOP like yours, with a special connector that 'bites' through the cable, is the best solution for a 'no-slack' situation.

 

I am using a 3 dB attenuator myself, my current + average DS/US power levels are 5/43 dBmV, compared to 8/41 dBmV on my previous modem (without the attenuator installed).

 

Do let me know if you have any further questions.

MattChapman
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Hi @tobiastheebe , AlleKabels finally delivered my attenuator, and I fitted it yesterday afternoon. As a result my modem stats are much better. DS/US averages 7/43 dBmV.

 

I also received a firmware update when I rebooted the modem after installing the attenuator, so that could have reasonably had an effect too.

 

I have a constant stream of correctable errors on the OFDM channel 33, but from what I have read online, lots of correctable errors on an OFDM channel is quite normal. Either way, I'm happy to see I have no uncorrectables after 24 hours of uptime!

 

So I have learned:

 

  • When dealing with DOCSIS there is such a thing as having too much signal.
  • When dealing with cable connections, an unterminated output (like on a splitter) can cause more noise, and therefore connection dropouts.

Thanks very much for your advice!

tobiastheebe
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Glad to read that the modem's power levels and uncorrectable errors have much improved after installing the attenuator.

 

Correctable errors on the OFDM channel are acceptable, since this channel is much wider than the SC-QAM channels and therefore much more susceptible to noise. As long as the uncorrectable errors remain 0, the correctable errors should have no noticeable impact on the internet connection's stability and speed.

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