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preston46's avatar
preston46
On our wavelength
2 months ago
Solved

Strange message on my hub 5 logs

I had a problem with my internet connection some time ago, 11 months to be exact, high T3 and T4 timeouts and hub 5 rebooting itself to correct the faults. I had numerous engineers come out, had inside cabling replaced 4 times and exterior cabling checked and replaced twice. I now getting the same fault appear on my virgin media, "intermittent area fault". Last time it was down to someone in my area connecting a faulty piece of equipment, also noticed a new fault fault I've not seen before on the Hub 5 logs.

RNG-RSP CCAP Commanded Power in Excess of 6 dB Below the Value Corresponding to the Top of the DRW;CM-MAC=;CMTS-MAC=;CM-QOS=1.1;CM-VER=3.1.

I'm on the 1GB service, anyone got any ideas as to what the problem might be this time?

  • Nednats's avatar
    Nednats
    2 months ago


    Thanks for sharing this — your logs look similar to mine, and I’ve also been chasing the cause of the same RNG-RSP CCAP Commanded Power in Excess of 6 dB Below DRW messages. I’ve also had DOCSIS 3.1 channels available, but the modem keeps falling back to 3.0 due to ranging failures.

    Given you've had external cabling replaced twice and the error is still present, that really does suggest this isn’t a cabling issue but more likely a provisioning or CMTS config mismatch, especially if upstream power remains high or unstable.

    If enough of us are seeing the same thing, it may point to a broader config or node-level issue. Let me know if your upstream power is also around 51–52 dBmV?
     

     

11 Replies

  • jpeg1's avatar
    jpeg1
    Alessandro Volta
    2 months ago

    Can you copy and paste the Hub upstream and downstream data here? 

  • preston46's avatar
    preston46
    On our wavelength
    2 months ago

    Keep getting the following message with copy and paste

    Your post contains invalid HTML. Remove the following invalid tags before publishing: div, li-table, li-td, li-tsection, p (data-lang-id)

    • Nednats's avatar
      Nednats
      On our wavelength
      2 months ago

      Paste into a text editor first then copy again.

    • jpeg1's avatar
      jpeg1
      Alessandro Volta
      2 months ago

      It's another of the apparently unfixable forum bugs. If you copy the text, exit the forum and reenter, then paste the text, that usually fixes it. 

      • preston46's avatar
        preston46
        On our wavelength
        2 months ago

        3.0 Upstream channels

        Channel    Frequency (Hz)    Power (dBmV)    Symbol Rate (ksps)    Modulation    Channel ID
        0    49600000    45.3    5120    QAM 32    1
        1    43100000    45.5    5120    QAM 32    2
        2    36600000    45.5    5120    QAM 32    3
        3    30100000    45.3    5120    QAM 32    4
        4    23600000    45    5120    QAM 32    5
        3.0 Upstream channels

        Channel    Channel Type    T1 Timeouts    T2 Timeouts    T3 Timeouts    T4 Timeouts
        0    ATDMA    0    0    0    0
        1    ATDMA    0    0    0    0
        2    ATDMA    0    0    0    0
        3    ATDMA    0    0    0    0
        4    ATDMA    0    0    1    0
        3.1 Upstream channels

        Channel    Channel Width (MHz)    Power (dBmV)    FFT Type    Modulation
        6    10.4    40.5    2K    QAM 256
        3.1 Upstream channels

        Channel    Channel Type    Number of Active Subcarriers    First Active Subcarrier (Hz)    T3 Timeouts    T4 Timeouts
        6    OFDMA    208    74000000    18    0

  • Nednats's avatar
    Nednats
    On our wavelength
    2 months ago


    Thanks for sharing this — your logs look similar to mine, and I’ve also been chasing the cause of the same RNG-RSP CCAP Commanded Power in Excess of 6 dB Below DRW messages. I’ve also had DOCSIS 3.1 channels available, but the modem keeps falling back to 3.0 due to ranging failures.

    Given you've had external cabling replaced twice and the error is still present, that really does suggest this isn’t a cabling issue but more likely a provisioning or CMTS config mismatch, especially if upstream power remains high or unstable.

    If enough of us are seeing the same thing, it may point to a broader config or node-level issue. Let me know if your upstream power is also around 51–52 dBmV?
     

     

  • gitty's avatar
    gitty
    Joining in
    2 months ago

    The CMTS maintains a 12 dB dynamic range window. It continually adjusts where the top of the window is to make sure that all the upstream channels lie within it (the power levels).

    At the time of this event, one or more channels were 6 dB or more below this top (half way through the window) - which may have been adjusted a moment after. Unless you have issues, ignore it. Even if there is an issue, this event is not necessarily the reason for it.

  • chillybeam's avatar
    chillybeam
    Just joined
    2 months ago

    That log message points to a signal issue your hub is struggling to communicate properly with the network. Could be another local interference or upstream faul might be time to get Virgin Media to recheck the area.

    • Nednats's avatar
      Nednats
      On our wavelength
      2 months ago

      Just to clarify the interpretation of the "RNG-RSP CCAP Commanded Power in Excess of 6 dB Below..." log:

      That’s actually an error condition not just a normal part of DOCSIS 3.1 startup. It means the CMTS is seeing a commanded transmit power mismatch that falls outside the acceptable range. This can result in ranging failures, fallback to DOCSIS 3.0, or unstable upstream behaviour.

      It’s often due to signal issues like attenuation, a bad connector, or even an amplifier misconfiguration but it's definitely not expected behaviour in a clean DOCSIS 3.1 connection