In reply to a post by Pheasant:

Technically it actually *is* FTTP, as in it fits the definition of fibre to the premises....

However Virgin Media FTTP uses neither of the 'typical' PON related architectures (GPON, NG-PON2 or XGS-PON etc.) nor for that matter Point-to-Point (usually 1Gbps or 10Gbps BiDi ethernet) FTTP network designs typically used by either Openreach or any of the other Altnets.

Instead they use DOSCIS 3.1 via RFoG and essentially media convert (using Vector Technologies, Boostral 610 or 711 modems) at the premises to back to coaxial for both their Hubs/modems and for set top devices.

Yes, ok, technically a fibre does reach the premises. However I would not put RFoG in the same category as PON or Ethernet FTTP technologies, mostly due to the latency.

The rest of what you said just repeats what I said

It's an important distinction, in as much with fibre running directly to the premises gives them far great flexibility to change the active devices at the greatest depth in their network - be that with DOCSIS 3.1 or in future DOCSIS 4 media converters or for that matter they could in theory actually adopt any other technology - they could even deploy a PtP or PON network if they desired.

The latency bogeyman that can plague them with HFC and earlier versions of DOCSIS could be mitigated with alternative traffic queuing strategies available in D3.1 (e.g. active queue management) and media acquisition in low latency docsis (LLD3.1)

Edited by Pheasant (Mon 22-Mar-21 08:53:14)

I still think the biggest reason HFC/RFoG kind of sucks is that it's not really in the same category, it's as much about delivery of TV services as it is Broadband.

It's possible to run GPON over the same fibre, this would be the future imo, but VM won't do it as they don't want any product offering differences vs HFC.

Honestly. VM are dead to me now, so many massive customer services issues, and a poor product. Thankfully CityFibre will reach me soon.

At least RFoG eliminates the potential for area-wide SnR issues, but yeah it can't solve congestion. Presumably the lasers are a different wavelength to GPON so they could overlay a better technology if they wanted to at a future date.

Pushing glass all the way to the premises with RFoG gives them a N+0 architecture (no amplifiers between the node and home) - a lot more capability to actually deliver stuff like full duplex DOCSIS and a literal pathway for symmetric 10G service, without all the inherent issues that would present on the present N+1 to N+10 topologies they have on HFC.

DOCSIS certainly isn't dead yet. They're pushing ahead with the next generation...Distributed Access Architecture, Flexible MAC Architecture, Remote-PHY and Coherent Optics.

https://www.cablelabs.com/on-the-path-to-10g-cablela...

By carving up and decentralising many of the key (but quite limiting) DOCSIS headend functions deeper into the network. They are in effect re-inventing DOCSIS from a central/shared entity to a distributed or switched/dedicated medium...

Note that VM can stay with RFoG for TV but choose something like EPON for broadband, all delivered over the same fibre. Obviously the ONT and hub 3/4 will have to be replaced, but that's no big deal.

Yes they could indeed, run side by side, ala hybrid PON. This is a older paper, but an interesting read.

HFC Transformation To FTTP: The role of RFoG, PON and Hybrid Solutions

Personally I don't believe VM would jump to the 'either' option in the UK. Think they have to much vested in D3.1 and they will continue the DOCSIS path for the foreseeable. But down the track who knows, having glass at the premises gives a huge scope.

Looking at that, if I where VM then I think the first step would be to remove a whole bunch of L3 cabinets, and wire all my L4 cabinets back to L2.5/3 with fibre.