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Author Topic: Openreach Trial SRA On UK FTTC Superfast Broadband Lines Again UPDATE  (Read 1211 times)

PhilipD

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Re: Openreach Trial SRA On UK FTTC Superfast Broadband Lines Again UPDATE
« Reply #15 on: April 17, 2018, 02:50:25 PM »

Hi

I think the only way out for us on ECI cabinets is hoping that OR start pushing G.fast pods on poles and manholes etc. That would solve the inequality of service we're getting as we would be all on the same pods, and if they were pushed closer to our houses we would get a genuine speed boost and be just like everyone else.

To be fair the speed differences are not that different, the main one is where interleaving is off because G.INP is enabled which can't happen on an ECI cabinet of course, but even then it's not a very noticeable difference.  I've been on ECI cabinets at two properties now and always had 80/20 with no interleaving.  The biggest decider to speed isn't ECI versus Huawei, it's distance, as always.

There isn't a huge inequality of service, just a small inequality for some connections.

I agree overall that G.Fast should never have been relegated to pods on the PCP, in my opinion any investment into the corroded copper telephone network should always result in some element of removing it, i.e. bringing fibre closer to homes.

G.Folly pods only benefit those people who don't need to benefit from a speed boost.

Regards

Phil
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Chrysalis

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Re: Openreach Trial SRA On UK FTTC Superfast Broadband Lines Again UPDATE
« Reply #16 on: April 17, 2018, 02:57:02 PM »

Its a domino affect really.

We dont know if ECI is capable of SRA or not, but even if it is, a decision may have been made that the other stuff needs to be working first as a prerequisite and as such no SRA on ECI.

So the falling dominoes would be.

Failed G.INP domino knocks the xDB DLM domino over which then knocks the SRA domino over.

I am curious what will happen to "IP profiles" with SRA, as SRA can change the sync speed every XX amount of seconds.  I cannot remember exactly how often it was on my ukonline service but I am pretty sure it was no longer than a minute. On ukonline it didnt matter as they didnt use IP profiles.  Also the potential compatibility fallout from this may be interesting as well.
« Last Edit: April 17, 2018, 03:00:30 PM by Chrysalis »
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Chrysalis

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Re: Openreach Trial SRA On UK FTTC Superfast Broadband Lines Again UPDATE
« Reply #17 on: April 17, 2018, 03:05:13 PM »


So here we are in 2018 saying why didn't Openreach buy V-41's when placing their orders in 2011.   Perhaps they may have done if there was such a thing as system level vectoring and V-41's actually available when they started designing their network.  It explains why Deutsch Telekom and France also rolled out FTTC with M-41's.  I guess you can't plan and order something which isn't yet available.  :'(

Do both those telcos still use the M41s and did they use only M41s or switch part way through?

Also SRA when working at its best is absolutely amazing.

My ADSL story was mostly talked about on tbb.

But basically I had an extremely bad line, it was really hideous and I am not exaggerating.

The attenuation was around 50db, and it synced at around 6400kbit on the downstream in optimal daylight conditions on fast path with a 6db SNRM.

In terms of stability there was the following problem.

1 - Been an overhead pole line at 50db attenuation it was affected by the nighttime, the upper half of the ADSL1 tones were decimated, bitswapping would fully disable about 10-15 tones so they remained off for the remainder of the sync, and the bitloading was all shifted to the first 50% of the tones, which under normal conditions should have handled it fine.
2 - Second problem, on working days, so monday-friday every week except bank holidays, there was a sudden large drop in SNRM across about 60% of the useable tones, most of it was focused on the strong lower frequency tones, given after a night most of the higher tones were turned off this was devastating to the line.  This would suddenly come on usually between 6.30am and 7.30am, then come and go randomly throughout the day, eventually stopping between 5 and 6pm.

It was a no win situation, if I synced "DURING" one of these events so with absolutely battered tones, I would sync at about 3-4mbit, but then when the first night came the line lost sync, and would sync with full bitloading again on the lower tones, but would be unstable again the following day when the noise burst appeared.  DLM obviously took action and the line would end up at a 15dn SNRM "and" interleaving.  But still was NOT stable.  I eventually moved to AAISP to try and deal with the problem, they improved it by getting me moved to a TI dslam that I believe had a broadcom chipset, but the line was never consistently stable.

Eventually I moved to UKOnline, line no more stable but at least didnt have to deal with DLM.  However a guy called Dan appeared on the tbb forums who worked for ukonline and he offered to enable SRA for tbb members.  When he activated it on my line it was WOW.  I went from resynching on a daily basis with huge periods of high packetloss as well when it failed to resync and just run with massive SES, to sync uptimes of over a YEAR.

It was not 100% flawless, it would go something like this.

6.44am no noise burst.
6.45am sudden noise burst.
X seconds of packet loss and ES
SRA kicks in and sync speed reduced live with no loss of sync.
Service stable no packet loss.
Noise bursts ends, SRA recovers the sync speed NO loss of sync.

BT eventually after a number of years said the issue was below a major road in the town centre on the E side, no chance of it ever been rectified.  Given the E side is not used on FTTC the problem doesnt exist now.
« Last Edit: April 17, 2018, 03:19:25 PM by Chrysalis »
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