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Author Topic: Broadcom's PhyR and G.Inp  (Read 2168 times)

Weaver

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Broadcom's PhyR and G.Inp
« on: May 19, 2022, 02:49:29 PM »

[Moderator note: This discussion has been split off from the "Fritzbox 7590 AX not talking to DSL" topic.]

As Alex said, I am using ADSL2 and lucky enough to have an exchange that uses a Broadcom chipset like my ZyXel modem so the two can speak the powerful PhyR L2 ReTx error correction protocol. This improves downstream performance greatly and allows me to safely run at 3dB SNRM downstream. This gives me about a 10-20% downstream speed improvement. See https://docs.broadcom.com/doc/1211168566993
« Last Edit: May 21, 2022, 05:47:28 PM by burakkucat »
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Edinburgh_lad

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Re: Broadcom's PhyR and G.Inp
« Reply #1 on: May 19, 2022, 05:39:32 PM »

This study is done by Broadcom. 'Something is rotten in the state of Denmark' one would want to state here in response...

Anyhoo, if the line is 'kaput', you can try as many PhyR technologies etc. as you want, but ultimately, the line would need fixed. Because, there's so much you can fix in terms of broken packets. (Just for comparison, you can glue two pieces together and the item may look like new, but ultimately, it'll be weaker in that area as a result.) So, I think everyone with problem lines has hopes that filters and different technologies will do magic there, but effectively, that's not the case: the issue must be tackled at the root.

Therefore, I'd argue that these PhyR technologies are only good for a temp problem, like occasional noise.
« Last Edit: May 19, 2022, 05:47:43 PM by Edinburgh_lad »
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Edinburgh_lad

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Re: Broadcom's PhyR and G.Inp
« Reply #2 on: May 19, 2022, 05:51:49 PM »

Yeah, the right word has come back to me: PhyR can be used as a way of 'minimising' the effects of issues, but not 'eliminating' them.

(Ipse) dixit.
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Alex Atkin UK

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Re: Broadcom's PhyR and G.Inp
« Reply #3 on: May 19, 2022, 10:41:10 PM »

Therefore, I'd argue that these PhyR technologies are only good for a temp problem, like occasional noise.

You seem to be overlooking the fact Weavers lines are very long, there is no "fixing" them.  It merely helps them to perform to their maximum potential.
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Edinburgh_lad

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Re: Broadcom's PhyR and G.Inp
« Reply #4 on: May 20, 2022, 12:37:55 AM »

But I thought this PhyR thing is about impulse noise protection, rather than length of the line. So, yeah, his line is long, but how does it relate to PhyR?
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Alex Atkin UK

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Re: Broadcom's PhyR and G.Inp
« Reply #5 on: May 20, 2022, 03:53:01 AM »

Longer lines will inherently pick up more interference but PhyR helps to stop that line losing sync and possibly even allow a slightly higher sync rate.
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tubaman

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Re: Broadcom's PhyR and G.Inp
« Reply #6 on: May 20, 2022, 08:34:27 AM »

PhyR is Broadcom's proprietary version of G.INP, and that is used to great effect on VDSL lines, allowing a reduction in SNR and thus increased speed as @Weaver has said.  I certainly wouldn't want to be without G.INP on my line as it effectively increases my sync rate by over 20%.
 :)
« Last Edit: May 20, 2022, 01:16:20 PM by tubaman »
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Weaver

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Re: Broadcom's PhyR and G.Inp
« Reply #7 on: May 20, 2022, 10:09:26 AM »

Long lines have more attenuation so the level of the signal at the far end is small compared to the noise and this, by definition, means low SNR. (Not to be confused with SNRM.) It may be though that the level of the signal at the source is turned way up because of the long line and so this cancels out the effect of the long length. Another thing, long lines don’t transmit high frequencies. I can’t get anything on tone 160.
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Edinburgh_lad

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Re: Broadcom's PhyR and G.Inp
« Reply #8 on: May 21, 2022, 01:09:36 PM »

PhyR is Broadcom's proprietary version of G.INP, and that is used to great effect on VDSL lines, allowing a reduction in SNR and thus increased speed as @Weaver has said.  I certainly wouldn't want to be without G.INP on my line as it effectively increases my sync rate by over 20%.
 :)

Over 20% is quite a lot. How's it possible to achieve that much? And how can you tell that without it, your connection's speed would be 20% less?
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j0hn

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Re: Broadcom's PhyR and G.Inp
« Reply #9 on: May 21, 2022, 02:14:08 PM »

This study is done by Broadcom. 'Something is rotten in the state of Denmark' one would want to state here in response...

The study is done by Broadcom because PhyR is a proprietary Broadcom technology. It only works between a Broadcom DSLAM and a Broadcom chipset modem.

Therefore, I'd argue that these PhyR technologies are only good for a temp problem, like occasional noise.

Why only good for a temp problem? It's basically G.INP.
It runs all the time. There are very few lines that wouldn't benefit from having it. It does wonders with different types of noise
In the UK it's only deployed on some BT Wholesale ADSL DSLAM's.

Having always been on a Huawei cabinet with no ability to disable G.INP you won't know how much it's likely helping your line.
With no error protection at all my line received around 2,000 ES per day. With G.INP it received 1 ES per day and that was from a light ballast in my house coming on at 7am everyday.
Not only does it lower error numbers but it can increase sync speeds, lower latency and eliminate packet loss.

G.INP was a bit of a game changer with DSL. Many of the forums long term members remember it being rolled out and the difference it made to their lines.
Many of them on ECI cabinets saw the huge benefit only to have it taken away again.

There's a reason that the forums largest threads are discussing the deployment of G.INP.

Over 20% is quite a lot. How's it possible to achieve that much? And how can you tell that without it, your connection's speed would be 20% less?

Unlike G.INP, you can manually disable PhyR and see the difference.
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Weaver

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Re: Broadcom's PhyR and G.Inp
« Reply #10 on: May 21, 2022, 05:11:23 PM »

I don’t know how to disable PhyR on my modem - maybe there’s a setting somewhere though. I can compare the Broadcom-based ZyXEL VMG 1312-B10A units that I use now with the DLink DSL-320B-Z1 modems that don’t have PhyR and the downstream speed difference is about 500kbps out of 3Mbps, very roughly, and the DLinks have to use 6 dB downstream SNRM at a minimum all the time. So that gives me a chance of doing a comparison.
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burakkucat

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Re: Broadcom's PhyR and G.Inp
« Reply #11 on: May 21, 2022, 05:44:01 PM »

I don’t know how to disable PhyR on my modem . . .

Broadband ---> Advanced tab.

[This discussion has meandered away from the "Fritzbox 7590 AX not talking to DSL" topic, so I guess that a moderator needs to split it off.]
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j0hn

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Re: Broadcom's PhyR and G.Inp
« Reply #12 on: May 22, 2022, 12:24:23 AM »

PhyR itself likely won't make all that difference you see. Part of it might be the Broadcom chipset or the Zyxels additional noise filter.
If PhyR on your ADSL works like G.INP does on VDSL2 it will give a small increase in sync speed. The additional stability and very large reduction in errors due to using retransmissions means lines can run at lower SNRM targets which is where the biggest chunk of speed comes from.

In my example above I said my line received around 2,000 ES per day with no error protection on (fastpath). What I didn't say was that was at 6dB.
G.INP reduced this to 1 ES at 3dB.

I've had the luxury of having my pair swapped between our ECI cabinet that I used for around 3 years, on to the newly installed Huawei cabinet.
As there was an issue with the E-Side during the changeover my account wasn't formally activated by BT or Openreach until it was fixed so it ran for a couple months with no DLM. There's a thread about it somewhere.
The line was stuck on fastpath the whole time hitting thousands of ES some days.
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tubaman

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Re: Broadcom's PhyR and G.Inp
« Reply #13 on: May 22, 2022, 09:04:32 AM »

Over 20% is quite a lot. How's it possible to achieve that much? And how can you tell that without it, your connection's speed would be 20% less?

A lot of that gain is from it reducing the SNRM on the downstream from 6dB to 3dB.
I know what my connection is like without it as I've had it since before G.INP came online.
 :)
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