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docsis 3.1 latency

just a question of curiosity more than anything , but I was under the impression that with the new docsis 3.1 we would see some or at least a slight reduction in over latency with virgin, sadly for me at least this wasn't the case and the latency and bqm graph looks no different. im just wondering if any one who's tech savvy could break this down further and give us an insight into why there was no improvements in latency reduction.

 

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Re: docsis 3.1 latency

Hello

Can you please post you BQM.

Regards Mike

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Re: docsis 3.1 latency

The fundamental benefit of D3.1 is increased bandwidth and better use of the wireless spectrum between CMTS and the cable modem.  There's no inherent changes that will materially improve latency, although improvements in signal processing speeds probably make a very small improvement.  I have seen a solitary Hub 4 BQM where latency looks a tiny, tiny bit better than a Hub 3, but most Hub 4's seem to be the same or worse.  D3.1 is more demanding of line quality, so to me that's an expected outcome. 

Low Latency Docsis is now part of the D4.0 specification (along with symmetrical upload/download potential), but even that isn't a panacea, because it isn't inherently lower latency, rather it is based on trying to improve traffic scheduling between CMTS and modem as I understand it, so there' limits to what can be done.  VM won't even start to think about D4.0 until they've completed the D3.1 rollout and the dust has settled, then there's trying to make a business case for the billion pound plus costs of rolling out D4.0.  I'd be surprised if VM could make a case for investing in D4.0 if there's widespread availability of Openreach FTTP, and even if they could we're talking about a rollout between 2024-27.

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Re: docsis 3.1 latency

Low Latency DOCSIS is also part of 3.1 and is now supported by the newest software release for E6000. VM is probably already testing it.
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Re: docsis 3.1 latency

@gitty  Fair comment, but it doesn't seem to appear to be in the D3.1 rollout that VM are in the middle of (indeed comments in the forums suggest that VM have pioneered their own unique form of HLD).  

As for testing it, I'm confident you're right, as they've already been trialling full duplex DOCSIS (in Theale, was it?  There was a press release) and speeds up to 2.5 Gbps both ways.  I'd be very surprised that they'd attempt a mid major release upgrade to D3.1 LLD from a cost or operational risk point of view, and more so given that they've never really worried too much about latency before.  So I'm happy to be corrected that LLD can be part of D3.0, but I'll stand by my unproven projection that for the VM masses LLD arrives along with FD as part of D4.0, sometime around 2026.  Even that assumes that the O2 tie up doesn't mean that user-enhancements for fixed broadband customers don't take a very inferior second place to network enhancements to give "Vim2o" a leap-frogging advantage in national 5G mobile roll out.  

Happy to be proven wrong, and interested to hear your take?

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Re: docsis 3.1 latency

LLD comes as a sofware upgrade (CMTS+modem), so nothing is stopping them from introducting the feature at a later date. This goes for all operators in the world: LLD is a feature that comes after the initial rollout of 3.1.
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