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[Bowdon]

BT Partly Suspends G.INP Roll-out to ECI Fibre Broadband Cabinets

Openreach (BT) recently began the roll-out of Physical Retransmission ReTX (G.INP) technology to their ECI based Street Cabinets, which can improve the performance of their 40-80Mbps Fibre-to-the-Cabinet (FTTC / VDSL) lines. But this has now been partly suspended after problems occurred on some lines.

The G.INP (ITU G.998.4) technology is an error correction solution that is designed to help resolve spikes / bursts of Electromagnetic Interference (impulse noise), which can affect the stability and performance of related lines. Impulse noise generally comes in two main forms – intermittent and repetitive, which we’ll briefly explain below.

[Chrysalis]

yeah, but sadly that statement seems not 100% true, as I never had g.inp at all, they are suggesting they have only disabled it for lines who had it enabled but had problems.

[digitalnemesis]

Perhaps the reason why G.INP doesnt work as well as interleaving on some noisier lines is due to high levels of retransmissions resulting in greater latency when this occurs?

[loonylion]

Perhaps the reason why G.INP doesnt work as well as interleaving on some noisier lines is due to high levels of retransmissions resulting in greater latency when this occurs?

G.INP latency is momentary, interleave latency is permanent. G.INP should always be preferable.

[digitalnemesis]

Yes but what I'm trying to say is on certain extremely noisy lines then there would be extreme levels of retransmissions on G. INP resulting in decreased sync rates and increased average latency?

So G.INP would be great on lines with sporadic bursts of noise but on lines with continuous interference,  constant retransmissions would cause DLM to further reduce sync to compensate? Perhaps interleaving would be better anyway?

[kitz]

yeah, but sadly that statement seems not 100% true, as I never had g.inp at all, they are suggesting they have only disabled it for lines who had it enabled but had problems.

Unfortunately it also doesnt quite tie up either with the PPP type faults and why they had to remove it - even on lines which weren't affected.

“Openreach constantly monitors its fibre network and this identified some lines which would perform better without retransmission.

We’ve returned these lines to a pre-retransmission state, so that customers continue to receive the optimum speed. All other lines on the platform remain enabled with retransmission.

I cant see any reason why your line would not benefit from g.inp unless it was hardware related.

All credit to Mark though for trying to find out more info.

[kitz]

Yes but what I'm trying to say is on certain extremely noisy lines then there would be extreme levels of retransmissions on G. INP resulting in decreased sync rates and increased average latency?

There's some white papers around which state that g.inp doesnt work as well with certain types of noise and in those cases FEC is better.
Too tired to search, but iirc there is a concise article from ASSIA which would be the best place to start.

[kitz]

Here you go.

Knowing that ASSIA had some info, it was very easy to find - see image attached below

frequent short bursts - recommended FEC & Interleaving  -   (REIN)
Intermittent bursts >1ms - recommended g.inp  - (SHINE)

[digitalnemesis]

Perfect cheers darlin

[William Grimsley]

Perfect cheers darlin

Ok...

[kitz]

nowt wrong wi' that.  - Oop here we often say cheers-me-dears or cheers darlin if someone has done you a favour.
I may also say something like thank yee kind sir... and theres plenty of examples of me using the first and the last on this very forum. 

Makes the world a nicer and happier place ..
As long as its used in the right context it can put a smile on someone's face knowing what they did is appreciated. 

[William Grimsley]

Hehe, think I may have took it the wrong way. LOL.

[S.Stephenson]

Hehe, think I may have took it the wrong way. LOL.

You need to become fluent in northern 

We say hello to people on the streets it's marvellous.

[stevebrass]

Hehe, think I may have took it the wrong way. LOL.

You need to become fluent in northern 

We say hello to people on the streets it's marvellous.

You've got streets? Luxury!

[Black Sheep]

Hehe, think I may have took it the wrong way. LOL.

You need to become fluent in northern 

We say hello to people on the streets it's marvellous.

Agree wholeheartedly. Northern hospitality is leaps and bounds above our Southern cousins attempts.