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Confusing statements about RCP in MULPI doc

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Confusing statements about RCP in MULPI doc

I'm hoping someone here can clarify a couple of statements about Receive Channel Profiles (RCP) I came across in CM-SP-MUPLIv3.1.

Regarding D3.1 CMTSs:

From the 1st paragraph of A CM registering on a DOCSIS 3.1 CMTS MUST NOT communicate its receive capabilities using RCP encodings.

From the last paragraph of C.1.5.3: The CM MUST NOT send RCP encodings to a DOCSIS 3.1 CMTS.

Regarding D3.1 CMs:

FROM LAST PARAGRAPH OF SECTION If a CM advertising "DOCSIS 3.1" in the DOCSIS Version Capability (see the subsection DOCSIS Version in Annex C) communicates an RCP to the CMTS, the CMTS MUST reject the registration.

The first pair of statements seem to imply that D3.1 CMTSs don't use RCPs. That can't be right. Can it? Then what do they mean?

Similarly, the 3rd statement implies that D3.1 modems cannot send an RCP to the CMTS. That doesn't make sense to me either.

Only for D3.1 CM / CMTS combination?

Hi, just a guess without open the current specification: I think this is only for the combination of a D3.1 cable modem at a D3.1 CMTS. If we take a look at the current D3.1 cable modems then we see a minimum requirement of 2x2 OFDM/OFDMA channels and 32x8 SC-QAM channels. So in this case I would say the mess with the RCP from the D3.0 ages are not necessary anymore. Even if there will be a D3.1 cable modem which supports 4x4 OFDM/OFDMA channels the RCP stuff shouldn't be neccesary. In the D3.0 world the minimum requirement of a D3.0 CM was to have 4x4 SC-QAM downstream and upstream channels. Then the next generation had 8x4, 16x4, 24x8, 32,x8. Also in the beginning the 4x4 and 8x4 cable modems had used the concept of Receive Modules. So there was 8x4 cable modems available with 2x96 MHz downstream receivers. In this case the "smart" CMTS was able to generate dynamic downstream bonding groups based on the RCP if RCP verbose was enabled or you had to create a static downstream bonding group based on the RCP. But then the wideband capture tuners with the capability to pick the SC-QAM downstream channel across the entire frequency range up to 1 GHz came around and nowadays all D3.1 cable modem have those wideband capture tuners for its SC-QAM downstream channels by default. So the whole stuff with RCP and creating different downstream bonding groups with the size of 4, 8 or 24 downstream are not needed anymore for D3.1 cable modems at a D3.1 CMTS.

In the case of still supporting the older D3.0 cable modems the RCP stuff is still necessary even on the D3.1 CMTS and you're a lucky guy if you use a CMTS which can create dynamic bonding groups due the enabled RCP verbose option.

Just my though. :)

That makes more sense. The

That makes more sense. The first sentence of C.1.5.3 says "DOCSIS 3.1 cable modems support full band capture. Full band capture simplifies the receiver topology significantly in that there is only one level of receiver and there is full flexibility in assignment of receivers to channels.".

The section talks about both 3.1 and 3.0 modems so it's not clear to that the sentence applies to only 3.1 modems. I guess it should say " A DOCSIS 3.1 CM registering on a DOCSIS 3.1 CMTS MUST NOT communicate its receive capabilities using RCP encodings.'