Forum Discussion

mgilbert3's avatar
mgilbert3
Tuning in
21 days ago

Hub 5 power levels too high

I had a technician visit in early July who replaced the 6Db attentuator with a 3Db one.

Over the last week or so I have been having intermittent signal issues with packet loss leading to either poor internet connectivity or total packet loss. This can be seen in my BQM: https://www.thinkbroadband.com/broadband/monitoring/quality/share/7ea541f8314f0f8347708ae1d3c4c63207e4d95a

The downstream power levels across the 31 channels are from 8 to 10.1

The upstream power levels across the 5 channels are from 47.8 for channels 1 to 4 and 48.3 for channel 0.

I restarted the hub on 5/8 and since then have thousands of downstream pre and post RS errors and multiple T3-timeouts with upstream channel 4 being the worst at 237.

Extract from the route log below.

Can you please arrange for a technician to visit and resolve this issue.

09-08-2025 17:10:30warningDynamic Range Window violation
09-08-2025 17:10:30warningRNG-RSP CCAP Commanded Power Exceeds Value Corresponding to the Top of the DRW;CM-MAC=dc:99;CMTS-MAC=00d;CM-QOS=1.1;CM-VER=3.1;
09-08-2025 17:10:25noticeCM-STATUS message sent. Event Type Code: 24; Chan ID: 41; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 2 3.;CM-MAC=dc59;CMTS-MAC=00;CM-QOS=1.1;CM-VER=3.1;
09-08-2025 17:10:21warningRNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=dc:7:59;CMTS-MAC=00:0:5d;CM-QOS=1.1;CM-VER=3.1;
09-08-2025 17:10:20noticeCM-STATUS message sent. Event Type Code: 24; Chan ID: 41; DSID: N/A; MAC Addr: N/A; OFDM/OFDMA Profile ID: 2 3.;CM-MAC=dc:7:59;CMTS-MAC=00:d;CM-QOS=1.1;CM-VER=3.1;
09-08-2025 17:10:19warningRNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=d9;CMTS-MAC=00:0CM-QOS=1.1;CM-VER=3.1;
09-08-2025 17:10:14criticalStarted Unicast Maintenance Ranging - No Response received - T3 time-out;CM-MAC=dc:92;CMTS-MAC=005d;CM-QOS=1.1;CM-VER=3.1;

 

[Mod - MAC addresses removed for security]

9 Replies

  • pete_at_home's avatar
    pete_at_home
    Superfast
    17 days ago

    Downstream levels are slightly high based on VM's install practice, but well within the Docsis Standard (-15dBmV to +15dBmv).

    Either the network needs aligning properly (most likely), as your local network has too much US attenuation, and not enough DS attenuation !!   Chances are other people connected to the same street cabinet have similar issues, but simply haven't noticed !! 

    They could fit a Forward Path Attenuator to your line.   This will lower the DS levels leaving the US as they are. 

    If they fit a Wideband attenuator then the DS will drop, but the US levels will increase, leading to possible distortion & more issues !! 

     

  • mgilbert3's avatar
    mgilbert3
    Tuning in
    20 days ago

    Upstream 3.0

    ChannelChannel TypeT1 TimeoutsT2 TimeoutsT3 TimeoutsT4 Timeouts
    0ATDMA00190
    1ATDMA00790
    2ATDMA001240
    3ATDMA002060
    4ATDMA003320

    Upstream 3.1

    ChannelChannel TypeNumber of Active SubcarriersFirst Active Subcarrier (Hz)T3 TimeoutsT4 Timeouts
    6OFDMA2087400000030
    • Carley_S's avatar
      Carley_S
      Icon for Forum Team rankForum Team
      18 days ago

      Hi mgilbert3 
      Welcome back to the Community Forums. 

      Sorry to hear of your service concerns. Checking the systems on our side, we can see that the hub is out of specification and needs further investigation through an engineer visit. 

      Please join me in a private message so I can locate your account and pass the account security. You can see your private messages at the top of the page, in the envelope icon, or if you're using a smaller device, you can see your private messages by clicking on the Virgin Media logo at the top right and selecting 'Messages' from the drop-down.

    • Adduxi's avatar
      Adduxi
      Very Insightful Person
      20 days ago

      Terrible connection.  Let’s hope that’s an area fault somewhere?  Or maybe your cable is fractured? 

  • Adduxi's avatar
    Adduxi
    Very Insightful Person
    20 days ago

    You need to post all the stats, including PostRS and Upstream ones.  But yes, the DS power is a tad high and could be lower.

    • mgilbert3's avatar
      mgilbert3
      Tuning in
      20 days ago

      Downstream 3.0

      ChannelLocked StatusRxMER (dB)Pre RS ErrorsPost RS Errors
      1Locked4010537325240
      2Locked402190187753
      3Locked4017436116500
      4Locked4031000819319
      5Locked4019324916461
      6Locked4030665421606
      7Locked4019672619441
      8Locked4010926812713
      9Locked4010421720737
      10Locked4012898826188
      11Locked40752397645
      12Locked40937817911
      13Locked40816397416
      14Locked40598286231
      15Locked40558565847
      16Locked40520065639
      17Locked40459634633
      18Locked40436174328
      19Locked40351913996
      20Locked40289023754
      21Locked40262674016
      22Locked40250304347
      23Locked40213872979
      24Locked40121053071
      25Locked40162653526
      26Locked39163423425
      27Locked40158294063
      28Locked40118053257
      29Locked40102703051
      30Locked4091623312
      31Locked4071062915

      Downstream 3.1 

      Channel IDLocked StatusRxMER Data (dB)PLC Power (dBmV)Corrected errors (Active Profile)Uncorrectable errors (Active Profile)
      41Locked395.713169239591820489
  • mgilbert3's avatar
    mgilbert3
    Tuning in
    20 days ago

    Hi,

    Downstream:

    ChannelFrequency (Hz)Power (dBmV)SNR (dB)ModulationChannel ID
    16030000008.240QAM 25625
    241100000010.140QAM 2561
    34190000001040QAM 2562
    44270000009.940QAM 2563
    54350000009.940QAM 2564
    64430000009.740QAM 2565
    74510000009.840QAM 2566
    8531000000940QAM 25616
    9539000000940QAM 25617
    10547000000940QAM 25618
    115550000008.940QAM 25619
    125630000008.940QAM 25620
    135710000008.940QAM 25621
    145790000008.740QAM 25622
    155870000008.640QAM 25623
    165950000008.440QAM 25624
    176110000008.140QAM 25626
    186190000008.140QAM 25627
    196270000008.240QAM 25628
    206350000008.340QAM 25629
    216430000008.440QAM 25630
    226510000008.240QAM 25631
    236590000008.340QAM 25632
    246990000008.340QAM 25633
    256670000008.540QAM 25634
    266750000008.640QAM 25635
    276830000008.640QAM 25636
    286910000008.640QAM 25637
    29707000000840QAM 25638
    307150000007.940QAM 25639
    317230000007.840QAM 25640

    Upstream

    ChannelFrequency (Hz)Power (dBmV)Symbol Rate (ksps)ModulationChannel ID
    04960000047.55120QAM 641
    143100000475120QAM 642
    23660000046.85120QAM 643
    33010000046.85120QAM 644
    423600000475120QAM 645
  • Client62's avatar
    Client62
    Alessandro Volta
    21 days ago

    Our VM Hub's Log tab is full of similar records during perfectly normal operations.

    To see the Signal Levels please share the contents of the
    Downstream and Upstream status tabs.

    Post these detail in the same way that you did for the Log tab and lets see the situation.