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I have a cisco UBR with MC-28U D2 interface card.. Recommended config for RF interfaces ?

I got my test tool to boot up and work, but i am unable to get cable modem to lock down.. modem stuck at Init(rc)

i am thinking i dont have the upstream configured correctly.. Tool only shows 1UCD for only one upstream, im thinking modem will not boot up because not enough upstreams to lock down.

interface Cable4/0
no ip address
no cable packet-cache
cable bundle 1
cable downstream channel-id 100
cable downstream annex B
cable downstream modulation 256qam
cable downstream interleave-depth 32
cable downstream frequency 651000000
no cable downstream rf-shutdown
cable downstream rf-power 45
cable upstream max-ports 4
cable upstream 0 connector 0
cable upstream 0 frequency 36000000
cable upstream 0 ingress-noise-cancellation 200
cable upstream 0 docsis-mode tdma
cable upstream 0 channel-width 1600000 1600000
cable upstream 0 minislot-size 4
cable upstream 0 power-level 23
cable upstream 0 range-backoff 3 6
cable upstream 0 modulation-profile 41
no cable upstream 0 shutdown
cable upstream 1 connector 1
cable upstream 1 frequency 36000000
cable upstream 1 ingress-noise-cancellation 200
cable upstream 1 docsis-mode tdma
cable upstream 1 channel-width 1600000 1600000
cable upstream 1 minislot-size 4
cable upstream 1 power-level 23
cable upstream 1 range-backoff 3 6
cable upstream 1 modulation-profile 41
no cable upstream 1 shutdown
cable upstream 2 connector 2
cable upstream 2 frequency 36000000
cable upstream 2 ingress-noise-cancellation 200
cable upstream 2 docsis-mode tdma
cable upstream 2 channel-width 1600000 1600000
cable upstream 2 minislot-size 4
cable upstream 2 power-level 23
cable upstream 2 range-backoff 3 6
cable upstream 2 modulation-profile 41
no cable upstream 2 shutdown
cable upstream 3 connector 3
cable upstream 3 frequency 36000000
cable upstream 3 ingress-noise-cancellation 200
cable upstream 3 docsis-mode tdma
cable upstream 3 channel-width 1600000 1600000
cable upstream 3 minislot-size 4
cable upstream 3 power-level 23
cable upstream 3 range-backoff 3 6
cable upstream 3 modulation-profile 41
no cable upstream 3 shutdown

Most Popular Post
Sebastian Steinert on 24 Okt 2019 - Likes 1

Seems like all 4 upstream frequencies are all same value.

I think these value should have different values.


  1. Config looks good and ranging is complete but i guess the receive power level is inaccurate so that the CMTS can not detect the packets or better the modem can not send the signal with a lower power level what the CMTS probably tries to initiate.

    Are you sure you have enough attenuation between CMTS and modem? In general you should have about 40 dB attenuation. Then i would remove the upstream power level to default/zero. Otherwise try to set 10 to 20 dB attenuation between CMTS and modem with the configured power-level of 23.

  2. So I changed the config, ill post images below, I am using a VePal CX250 D3+ as testing CMTS... I am running UBR 7246 / 7200 1gig NPE and 2x MC28U's

    I changed the Frequency, 609 channel 88 I believe, lowered upstreams to  power 4  from 23.. downstream to 45... modem get to init(rc) then resets guessing modem flap.. also RF Service level where I am plugging in modem is -4.6 dbmv  see images below of modem verbose / modem flap / and test tool

    Modem Verbose

    Modem Flap MAC ending in 66 the other two are the test tool

    Downstream View from Tool


    see anything off..

    I was told RF Service level between -10 and + 10  this is 4.6

    Downstream + or - 10  Downstream is a little HOT @13

    Upstream is a little shallow @ 39.9 close to 40

    SNR is 45db no BER errors 0.0E+00

    Tool locks down - modem wont.

    any susgestions ?

  3. Received Power of 18.5 dBmV in the first picture should actually be 4 now if you set that up before you took the picture. Maybe the measurement tool can send with lower power, but the modem doesn't. I still think that you need to add approximately 20dB attenuation to the Upstream line between CMTS and modem - e.g. by 1x of this Amazon 20 dB attenuator

  4. Seems like all 4 upstream frequencies are all same value.

    I think these value should have different values.

  5. They were, changed, ALL UP AND RUNNING... Downstream was 8.1... I put a -10dbm attenuation on downstream side and SNR 44 Downstream -0.1 and upstream 44.5 !! modem Locked down and booted right up... I also landed up going with a cisco modem... it is backwards compatible... IE.. locks down to 1 downstream Docsis 2.0 MC 28U with NPE 1G

    Linksys CM3008 will no lock down because it requires D3 bonded downstreams...  I just ordered NPE-G2 with 1.2.33(SCA) show it will bond downstreams and make bronze.. but you need mc 28u / NPE G1 or NPE G2 with firmware 1.12.33 and higher..