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Author Topic: G.INP and ECI  (Read 30334 times)

Dray

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Re: G.INP and ECI
« Reply #90 on: April 09, 2015, 11:52:53 PM »

Just a guess but I'd say you don't work for Openreach, so where is this information coming from?
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Mike Turner

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Re: G.INP and ECI
« Reply #91 on: July 02, 2015, 08:26:09 AM »

I'm not sure if this is bad news for ECI cabinet users or not, but, after a VDSL reconnect this morning, I've lost G.INP on my ECI cabinet here in Martlesham Heath.

If it is of any interest, my basic before and after stats are:-

Attainable down from 62162 to 59221
Attainable up from 16631 to 18768
Actual down from 62162 to 51130
Actual up from 16631 to 18719
Latency down from Fast to 8ms
Latency up from 8ms to 0
INP down from 44 to 3
INP up from 2 to 0
G.INP down from On to Off
G.INP up from Off to Off
SNR down from 6 to 6
SNR up from 6 to 6
Bitswap down from On to On
Bitswap up from Off to On

It's all beyond me, but I can understand why losing downstream G.INP would lose me some downstream speed, but I don't know enough to understand why I should gain some upstream speed.
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Dray

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Re: G.INP and ECI
« Reply #92 on: July 02, 2015, 08:33:05 AM »

Shame you're not using MDWS, but it looks like G.INP mk2 has been applied.
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Mike Turner

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Re: G.INP and ECI
« Reply #93 on: July 02, 2015, 08:36:43 AM »

Surely, if that was the case, G.INP down wouldn't have gone from On to Off.
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WWWombat

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Re: G.INP and ECI
« Reply #94 on: July 02, 2015, 02:28:41 PM »

It does indeed look like G.INP has been removed entirely - though it looks like it only existed downstream anyway. We'd expect that, with an ECI cabinet.

In the old configuration, you had G.INP protection downstream (with INP=44, delay=0ms), and standard FEC+interleaving protection upstream (with INP=2, delay=8ms). This means you had a round-trip latency delay of 8ms (probably just over), and probably lost around 15% of the upstream bandwidth to the FEC process.

In the new configuration, you now have standard FEC+interleaving protection downstream (INP=3, delay=8ms), and no protection upstream (INP=0, delay=0ms). This means you still have a round-trip delay of 8ms (but it has swapped from being within the upstream path to being within the downstream path). Without FEC on the upstream, you notionally have more bandwidth available to the user data. However, on a lot of lines (at least where capacity is available), the modems choose to add extra FEC protection even when DLM hasn't asked for it; in your case, the spare capacity isn't there, so perhaps the modems haven't bothered to put it in place.
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Mike Turner

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Re: G.INP and ECI
« Reply #95 on: July 02, 2015, 02:38:34 PM »

Thanks for that clear explanation. My latency doesn't appear to have changed, (about 25 ms before and after), which fits with what you say.
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