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ReTX status with Lantiq VRX220 chipset ...

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madhatter:
I have a Netgear DM200 modem running OpenWRT 18.06.1.
I am on the BT 40/10 FTTC package and am interested in whether I'm on
Re-Transmission High or Low. My line is very stable and speeds appear to
be at the maximum for this package. I sync at 40Mb and get a Line profile
of about 36.80Mb.
I'm assuming that is 96.8% of 38Mb (contracted max. for this package)
- which would seem to indicate ReTX high - rather than 92% of sync speed.

I understand that the Broadcom based chipsets allow for a better/easier
command interface to determine ReTX status.

However, I've being playing around with Lantiq commands and appear to
have found some which give me line status details.

The following commands show the upstream and downstream status and
seem to show ReTX is enabled on the downstream but not on the upstream.
It's my understanding that is correct for my modem type connecting to a
Broadcom based cabinet. Whilst the first commands output appears to show
ReTX status, it doesn't show if it's High or Low.

The second command output shows my interleave depth (I think).
Is this enough to determine whether I'm on ReTX High or Low ?

Thank you in advance for any help.

# dsl_cpe_pipe.sh lfsg 0
nReturn=0 nDirection=0 bTrellisEnable=1 bBitswapEnable=1 bReTxEnable=0 bVirtualNoiseSupport=0 b20BitSupport=0

# dsl_cpe_pipe.sh lfsg 1
nReturn=0 nDirection=1 bTrellisEnable=1 bBitswapEnable=1 bReTxEnable=1 bVirtualNoiseSupport=0 b20BitSupport=0

# dsl_cpe_pipe.sh g997fpsg 0 0
nReturn=0 nChannel=0 nDirection=0 nNFEC=254 nRFEC=16 nLSYMB=2694 nINTLVDEPTH=1 nINTLVBLOCK=127 nLPATH=0

# dsl_cpe_pipe.sh g997fpsg 0 1
nReturn=0 nChannel=0 nDirection=1 nNFEC=32 nRFEC=16 nLSYMB=16 nINTLVDEPTH=1 nINTLVBLOCK=32 nLPATH=0

j0hn:
I don't think you can tell from the Lantiq stats.

It's about 96.7% off the sync speed (40Mb) for retx low and between 91-92% for retx high.

You're on retx high.

ejs:
It's not that ReTX is on for the downstream and off for the upstream due to your type of modem. The lfcg command should show it's enabled in each direction, if not, the lfcs command can enable support for it, if that can't, then that'll be because your VDSL firmware version is old (I think 5.7.x.x.x.x and later versions have upstream ReTX support). It's on for the downstream and off for the upstream because that's how Openreach choose to do it (granted how Openreach choose to do it is partly due to modems lacking support for it years ago).

Unfortunately the lantiq commands do not properly handle more than one bearer channel, so those framing parameters including the interleaving depth for the downstream could be for the other bearer. In any case, I don't think you can determine retransmission high or low from the interleaving depth.

If g997csg 0 1 gives ActualImpulseNoiseProtectionRein, then that's the INPRein figure, 0 indicating ReTX low and 1 indicating ReTX high. The lantiq commands output INP values in units of 0.1, so ActualImpulseNoiseProtectionRein=10 would equal INPRein=1.00.

madhatter:
Thank you both for the updates.

The output from the g997csg command is

# dsl_cpe_pipe.sh g997csg 0 1
nReturn=0 nChannel=0 nDirection=1 ActualDataRate=39950000 PreviousDataRate=39998000 ActualInterleaveDelay=16 ActualImpulseNoiseProtection=440 ActualNetDataRate=39998000 ActualImpulseNoiseProtectionRein=0 ActualImpulseNoiseProtectionNoErasure=40

so as ActualImpulseNoiseProtectionRein=0 does that mean ReTX is low ?

Am I correct in assuming ReTX Low is better, in as much as you get more of your potential
maximum line speed ?
Regarding the line itself, I live next door to my local exchange and the green cabinet (PCP)
and it's associated fibre cabinet are about 100 yards away in the opposite direction.

j0hn:
Retx Low gives a better throughput with the IP profile being around 96.7%.
It is only an exact figure of 96.69% on Broadcom chipsets.

Retx High gives an IP profile of 91-92%

ActualImpulseNoiseProtectionRein=0  might suggest your line is retx low, but the IP profile is that of an retx high sync.
It's exactly 92%

Some ISP's will be happy to run a GEA test for you which will state the DLM profile of retx high/low, but it quotes the line from 13 days ago so recent changes would be missing.

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