Openreach G.INP Trial on ECI FTTC Broadband Lines Hits Snag UPDATE

Openreach’s (BT) long-running efforts to apply ReTransmission (ReTx / G.INP) technology to UK Fibre-to-the-Cabinet (FTTC / VDSL2) based broadband ISP lines at ECI using street cabinets may have hit yet another snag, which appears to have resulted in the enhancement being removed from some lines.

At present a huge proportion of broadband consumers in the UK are still using the hybrid fibre FTTC service and will probably continue to do so until the FTTP roll-out reaches more of the country. As such anything that can improve the performance of those existing connections remains important, which is where ReTx (aka – G.INP) comes into the picture.

G.INP (ITU G.998.4) is an error correction solution that is designed to help resolve spikes of Electromagnetic Interference (impulse noise), which can improve a line’s stability and thus performance. The introduction of this technology can, on some VDSL2 lines, even produce a small to modest increase in service speed (downloads).

The technology is nothing new to Openreach and they’ve already got it to work on their larger estate of Huawei based cabinets, but unfortunately the same cannot be said for those using kit from ECI. Various past attempts have been made to fix the ECI issues and all have run into problems. A new attempt was started earlier this year (here) and then extended in June 2020 (here).

However, since the start of August 2020, a number of those who recently had G.INP applied to their lines as part of the trial have now seen it vanish. Interestingly none of those reporting this to ISPreview.co.uk said they’d suffered any problems and all noted that errors on their line had reduced, while speeds also increased (one person even saw their downloads jump by an extra 9Mbps).

Sadly, Openreach did not respond to our request for comment, although we understand from others that the trial may have produced mixed results and encountered an unexpected problem with some DSLAMs (cabinets). A confidential briefing on this does exist, but we don’t have access to that (here). We can only hope that they’re able to find a solution.

UPDATE 21st August 2020

We’ve been able to get a little more detail from various sources (and thanks to all those people who keep reporting their experiences of G.INP to us). The briefing itself is quite short, but the key piece is this.

Extract from Openreach Briefing on G.INP

Unfortunately the larger loads towards the end of the trial have highlighted some unforeseeable issues whereby CPE [VDSL broadband routers etc.] would fail to sync, despite the GEA Service Test usually showing the circuit as testing ok. Our early root-cause analysis has indicated that this is related to an issue in the DSLAM.

We have discussed the issue with impacted CPs and, as a precautionary step while further analysis is undertaken, we have acted promptly to remove ReTx from any ECI lines that could be negatively affected. Further updates will follow once we have more information.

The statement confirms what we said above, which is that they’ve so far only removed it from some lines. Openreach also states that the “early indications from this trial were that speed a stability were increased.”