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[Ktor]

Faulty cabinet firmware and/or faulty DLM who knows. I still have had pointless and undesired interleaving for 3 months and counting.

So I asked the ISP for a deadlock statement so I could take the problem to arbitration. They offered to register a complaint with BT Openreach which I accepted and as usual they do nothing for a week then contact me to ask if I really wanted a complaint lodged with openreach, which, of course I did.

Lucky me instead of the ISP ignoring me I get to be ignored by BT Openreach for two weeks before they also tell me to p1ss off. Apparently some operations manager doesn't know anything about cabinet firmware and some 'coach' says nothing could be done without reporting a fault and is isn't a fault so you can't report it.

Just as I have said all along "We don't give a crap, take what we give you and like it".

Back in march when I was told an overnight 20% drop in downstream speed and 25ms more latency from bi-directional interleave wasn't a fault and to p1ss off I started maintaining the attached modem stat (Unlike copper and cabinets BT/ISP don't have a monopoly on being aholes). I didn't imagine I would still be maintaining it 3 and a half months later - looks like I will be for at least another 6 months of pre-paid line rental before I probably switch to Virgin. The idea of buying anything from BT has become abhorrent, I already ceased a second land line for that reason.

I mentioned the stat to the ISP guy today, he told me the package was unlimited and bandwidth doesn't cost them anything - so that's all-right then - lol.

[WWWombat]

I have G.inp and i hate it,because it adds latency,with g.inp i have interleaving depth of 8 up/down cuz i have the inp 61 up/down delay 0,

I think you are getting slightly confused.

INP generally stands for "impulse noise protection", and VDSL2 uses values for INP to offer protection against noise. However, "G.INP" isn't the same as "INP". It is a different means to protect against noise by using "retransmission".

When looking at line statistics, you can usually tell that G.INP (retransmission) is in use when the "INP" value is set to something much higher: above 30 is common in the UK and in Ireland. Alongside this, the "delay" value would be set to 0 (zero, so there is little additional latency), and interleaving depths will be 0, 4, 8 or 16.

In your case, "INP" is set to 2 (up and down), and "delay" is set to 8ms down and 3ms up. Those values suggest that G.INP (retransmission) is not in use. Instead, your modem is using old-style INP settings that turn on FEC and interleaving, and allow for 11ms of additional latency.

Beyond that, I don't know of tweaks that you can use - others may be able to guide you better. However, in the UK, our telco has locked down the DSLAM so that it ignores almost all the tweaks you could set. I believe you can deliberately set a lower speed, in the hope that this reduces error rates, which in turn persuades the system to put you back on fastpath.

[willc]

that's the issue.the inp.i have like 40k forward errors corrected a day (specially when gaming,i get even more),and the correction adds latency,on bf4 30% of my hits don't register(not bf4 hitreg problem,got fixed).only way from what i saw on uk forums,to have the line in fast is (to disable g.inp in my case) then inp 0 and delay 0,that way forward errors will not be corrected.i didn't see people with g.inp enabled and inp 0 delay 0 or some kind of fast lane with g.inp.
so that's why i'm asking if somebody knows a modem with CO settings usable on CPE,since my dslam accepts modifications from the modem.the dslam is a Selta SAMBHA 200.

[Dray]

I recommend you to have G.INP enabled rather than any alternative.

[willc]

well in this situation yes,cuz without is worse.but still, the correction its simply a disaster.before with adsl2+ fastpath had a ping of 10 on a server test,now its 19/20/21,and its not a cable problem or something like that,cuz the technician did some tests on the line with a tester and it's ok.
somehow if i set a data rate of 100 down and 1 up, the interleaving depth in upload changes to 2 from 8, with the same inp of 61 but snr goes to 32db from 11db.

[Chrysalis]

Cannot advise you really as you in italy and no idea what their policies are but on a technical level.

fast path = minimal added latency, however errors may cause packet loss.  Which would be hits not registering in games if the packet loss is bad enough.
interleaving with no g.inp = permanent increased latency, base latency is higher but jitter remains same as fast path.  Much less likely to get packet loss than fast path.
interleaving via g.inp = variable latency, when errors need correcting latency for the affected packets will increase, so you have comparable base latency to fast path but jitter is introduced.  This is typically the most desirable configuration, as jitter is better than packet loss.

The only 2 modems I can think off that might give you the ability to overide the dslam in this case is either the asus devices or possibly the fritzbox devices.  Its not something that I have ever seen as a publicised ability and I have never heard of anyone in the world been able to overide the isp's interleaving configuration in this way.

[WWWombat]

only way from what i saw on uk forums,to have the line in fast is (to disable g.inp in my case) then inp 0 and delay 0,that way forward
errors will not be corrected.i didn't see people with g.inp enabled and inp 0 delay 0 or some kind of fast lane with g.inp.

I'll repeat: "INP" is not the same as "G.INP".

In the UK, we have 3 basic modes of operation:

1) Fastpath
INP=0, delay=0.
Most susceptible to errors
In mode (1), G.INP is not active.

2) Interleaving and FEC
INP=3 or 4, delay=8ms, 12ms or 16ms
With these settings, interleaving depth is around 1,000 and latency increases by between 8ms and perhaps 20ms.
In mode (2), G.INP is not active.

3) Retransmission - aka G.INP
INP=40-50, delay=0.
With these settings, retransmission is the main protection method, but small amounts of interleaving exist. The interleaving depth is less than 100, and the latency doesn't increase in any appreciable manner.
In mode (3), G.INP is active. Retransmission is used when errors occur.

In the UK, mode (3) - with G.INP enabled - is generally thought to be the best mode to use - it gives the lowest error count, with the lowest impact to latency for gamers.

It looks like your line is currently in mode (2), or the Italian equivalent.  You do not need to try to disable "G.INP" because it is not turned on for your line.

[j0hn]

.the dslam is a Selta SAMBHA 200.

looks like a nice piece of kit
http://www.selta.com/ProductDetail?id=01t20000004m10XAAQ
look into the Asus DSL-AC68U, absolutely useless in the UK. might be better on an unlocked dslam.

[willc]

the asus has same configs like mine.what i need it's something like this:manual page 17,look at the image.those settings work if u choose the CO mode aka mini dslam,u create a vdsl line to transmit,and you choose the parameters.i need those settings in CPE mode,to modify the line i receive.i looked at some modems,and all of them work the same,CO u have parameters,CPE no parameters.

@WWWombat

i'm in mode 3,but i can get in mode 2 using telnet commands on my modem "xdslctl configure --Ginp 0x0",but i can't get in mode 1 cuz my modem doesn't have inp and delay commands, and my isp have only 2 profiles, mode 3 and 2,doesn't have mode 1, and don't want to do it,and that's what i'm trying to do,but i need a modem with those settings.

[WWWombat]

@willc

I don't think you are in mode 3. The screenshot show INP values of 2 and "delay" values that are non-zero: both are clear indications that you are in mode 2.

If you used to be in mode 3, and have put yourself into mode 2, then undo everything - you made things worse. If you want better latency for your gaming, mode 3 is better.

Also note that, in general, the telco companies do not want you to be able to tweak your settings, or to adjust your line profile. Even when you make a change at your side, there is no guarantee that the DSLAM will stick to your setting ... and, as you have discovered, some settings are only possible on the DSLAM side anyway.

There are modems that will let you (try to) tweak your target noise margin. However, in this country, the VDSL2 DSLAMs will ignore that, and use a target of 6dB anyway. Here, there are almost no tweaks that work - and I haven't heard of a single person who has managed to tweak INP and delay settings to result in fastpath. Not one, in 6 years.

[willc]

@WWWombat
you didn't read my post well :

I have G.inp and i hate it,because it adds latency,with g.inp i have interleaving depth of 8 up/down cuz i have the inp 61 up/down delay 0, and it's bad at playing online games,30% of my hits wont register.so from my modem i can disable G.inp, but the interleaving depth will go to 837 down and 285 up cuz inp will go to 2 down/up and the delay will go 8 down 3 up,so it's worse, my ping will go +5/7 in speedtest and will not talk bout gaming.

so ye, i'm in mode 3 cuz 2 is worse,and can't find nothing that has some inp and delay tweaking

[WWWombat]

Yes @willc, I did read your post. I was mislead by your screenshot which seemed to contradict what you wrote in the text.

In the same quoted text, I'll highlight the bit that we should pay attention to now:

I have G.inp and i hate it,because it adds latency,with g.inp i have interleaving depth of 8 up/down cuz i have the inp 61 up/down delay 0, and it's bad at playing online games,30% of my hits wont register.so from my modem i can disable G.inp, but the interleaving depth will go to 837 down and 285 up cuz inp will go to 2 down/up and the delay will go 8 down 3 up,so it's worse, my ping will go +5/7 in speedtest and will not talk bout gaming.

G.INP/retransmission adds virtually no latency, compared to the old-style FEC+Interleaving settings (in the UK: INP=3, delay=8ms).

My calculations are that, when retransmission is activated in the UK (with INP settings higher than 30, and delay=0), the small amount of "interleaving depth" (and "interleaving block size" )amounts to around 0.2ms of latency, compared to the 8-16ms of latency that BT used to allow.

I can't calculate the equivalent figure for you, as you haven't given us the same data for running with G.INP. Without G.INP (with INP=2), your line has added latency of 11ms.

Here in the UK, the 0.2ms seems to be pretty much invisible.

If your gaming is suffering, I suspect there may be other more significant causes than the 0.2ms that comes from G.INP activation.

Do you have access to something that monitors your ping times 24 hours a day? To see how consistent your ping times are?

I have one of these running from somewhere in London, pinging my router once a second, and producing graphs like this:

can't find nothing that has some inp and delay tweaking

I don't think you ever will.

[forceware]

My line is used mostly for gaming, I can say for my line g.inp mode was the best experience for me. Fast path was in second place followed way behind by interleaving and fec which I'm currently on. Desperately waiting for a eci g.inp fix.

[willc]

My line is used mostly for gaming, I can say for my line g.inp mode was the best experience for me. Fast path was in second place followed way behind by interleaving and fec which I'm currently on. Desperately waiting for a eci g.inp fix.

it depends,every case is different.in my case i have a lot of FEC 80k a day when gaming,normally 40k,means that errors get corrected,that's what increase latency,and the inp@61 up/down does it.looking at a table here  Burst Protection  adds huge latency.

[forceware]

The highest number I see on that table is 4ms which isnt a great deal to be honest