Docsis 3.1 , Moca and Moca filters.

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jea101

Occasional Visitor
I just got a E31U2V1 Docsis 3.1 cable modem from Spectrum.

E31_2V1 Data Sheet Charter 1-page.pdf (dslreports.com)

I noticed that it has a frequency range of up to 1218 MHz which conflicts some Moca frequencies.

Also, 1218 is above the spec for Moca filters.

Currently I have a Moca filter installed where the cable enters the house.

Is this filter a problem with Docsis 3.1.

Docsis frequencies also appear to conflict with Moca 2.0.
 

degrub

Very Senior Member
you should look at the down/up frequencies used by your ISP for DOCCIS3.1 to determine if the moca filter will interfere.
Your moca modems will need to use the upper bands of the moca range. You should be able to set that in the configuration page.
 

krkaufman

Senior Member
I just got a E31U2V1 Docsis 3.1 cable modem from Spectrum.

E31_2V1 Data Sheet Charter 1-page.pdf (dslreports.com)

I noticed that it has a frequency range of up to 1218 MHz which conflicts some Moca frequencies.
Yes, DOCSIS 3.1 and MoCA specs define overlapping frequencies, which *can* be an issue. (see: MoCA vs. DOCSIS 3.1: Whose Spectrum Is It?)

The optimum solution, longer-term, is isolating the cable modem from the shared coax plant where MoCA signals are present, allowing DOCSIS to evolve however it wants ... 3.1, 4.0, etc ... without DOCSIS or MoCA getting in each other's way.

Shorter term workarounds (depending on the circumstances) include protecting sensitive DOCSIS 3.1 modems/gateways from MoCA signals by installing a MoCA filter on the modem's coax input port (when the provider isn't yet utilizing D3.1 frequencies above 1002 MHz); or configuring the MoCA network to operate above the D3.1 frequencies (when the provider *is* utilizing D3.1 frequencies in the 1002-1218 MHz range[1]), but at the expense of a MoCA 2.5 network's maximum throughput where fewer than 5 channels would be available for bonding.

NOTE[1]: One roadblock to DOCSIS 3.1 and MoCA harmony on shared coax, even if the MoCA network is configured to operate above the D3.1 frequencies, is the lack of availability of "PoE" MoCA filters spec'd to accommodate the shifted pass-band/stop-band for such a setup. They exist (see here), but retail availability is ... scarce(?).​


So, yeah, check your modem/gateway to determine what DOCSIS frequencies your provider is currently using for your Internet connection's download/upload channels ... but be sure to do so via a coax link unfiltered by an existing "PoE" MoCA filter. For example, that MoCA filter that you currently have installed...

Currently I have a Moca filter installed where the cable enters the house. ... Is this filter a problem with Docsis 3.1.
... would be blocking DOCSIS 3.1 signals between your provider and D3.1 modem, assuming your provider is utilizing these frequencies for service delivery. That said, if you're receiving your spec'd download/upload rates with your current setup, with the "PoE" MoCA filter in place, then it's unlikely that your provider is using D3.1 frequencies above 1002 MHz -- but you can confirm this by removing the filter, rebooting the modem, and then accessing the modem diagnostics to verify the frequencies in use.
 
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krkaufman

Senior Member
NOTE[1]: One roadblock to DOCSIS 3.1 and MoCA harmony on shared coax, even if the MoCA network is configured to operate above the D3.1 frequencies, is the lack of availability of "PoE" MoCA filters spec'd to accommodate the shifted pass-band/stop-band for such a setup. They exist (see here), but retail availability is ... scarce(?).
Well, another speed bump (if not roadblock) to coexistence of D3.1 and MoCA on shared coax is what the MoCA devices allow for configuration. An adjusted, optimum MoCA 2.5 setup coexisting with D3.1 would allow for 4 bonded channels, per the MoCA 2.5 spec...

D31 and MoCA coexistence.png

... but mileage may vary as to what specific MoCA adapters allow as regards customizing the operating frequency.

For example, goCoax's support page indicates the only options are Full, D-Low and D-High, allowing only 3 bonded channels when configured to avoid D3.1 frequencies:
Does the admin GUI also allow configuring the MoCA frequency channel you want the extenders to run on?
Yes, our products can support this. Our device can support MoCA D-band low, D-band high and D-band extend three configurations. By default, we enable all of them. It will setup a 5-channels connection, from 1125MHz to 1625MHz. We know that, many MSO use D-band low 1125MHz to 1225MHz to act as MoCA WAN. You can change our device to use D-band high only, from 1350MHz to 1675MHz, can build a 3-channels connection.


Perhaps not coincidentally, even the Lindsay Broadband "PoE" D3.1/MoCA filter appears to support only the D-High configuration (1350-1675 MHz stop-band), rather than a 4 channel setup (1275-1675 MHz).

edit: p.s. To be fair, the MoCA 2.5 spec does offer this comment Re: the "transition band" between the D3.1 and MoCA 2.5 ranges:

"Note that the transition band between DOCSIS 3.1 and MoCA 2.5 will require careful engineering and filtering to avoid interference. "

... plus this statement from the "whose spectrum is it?" article:

"For example, how much of a guard band is needed between the utilized frequencies to avoid interference by the stronger signal?"

CC: @gocoax
 
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jea101

Occasional Visitor
Spectrum has disabled access to the status pages via the Ethernet port on newer modems.

In theory, I could buy my own modem but they only fully support their modems that are bundled in the price.

Currently I have the 200/10 internet service and am getting 230+ on their speed test.

I will be upgrading to 400/20 in February.

At this time my Moca adapters are on separate coax so I can remove the filter on the “cable” coax.

I could also move the modem to where the cable comes into the house but that requires another splitter that adds 3.5 to 4 dB loss to the rest of the cable outlets.

This is getting complicated.
 

krkaufman

Senior Member
This is getting complicated.
What's complicated? It sounds like you have a working setup, even an ideal one if the modem's coax line from the provider is isolated from the rest of your MoCA-infused shared coax.
At this time my Moca adapters are on separate coax so I can remove the filter on the “cable” coax.

Per previous:
The optimum solution, longer-term, is isolating the cable modem from the shared coax plant where MoCA signals are present, allowing DOCSIS to evolve however it wants ... 3.1, 4.0, etc ... without DOCSIS or MoCA getting in each other's way.

If the modem coax is isolated from the rest of your coax plant, yes, you *should* remove the MoCA filter on the incoming line ... as it would be blocking DOCSIS 3.1 signals if/when your provider begins using them; plus, it's no longer necessary. That said, the MoCA filter might be useful elsewhere on your shared coax segment, depending on how the coax lines are interconnected; or just store it.
 
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