Kitz Forum

Broadband Related => ISPs => Topic started by: re0 on May 24, 2019, 01:42:23 PM

Title: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: re0 on May 24, 2019, 01:42:23 PM
Since moving to Zen's G.fast service, I get the full 330/50 sync at about 200m. But one thing that is clear is that single-thread speeds, while not appalling, are pretty poor compared to multi thread.

Just to give some figures, speedtesters are giving 220-280 Mbps and multi-thread downloads seem to be hitting that 300 Mbps mark. However, single-thread downloads are a bit enemic since speedtesters say usually under 100 Mbps and just trying HTTP downloads from different sources seldom reach max speed, and it's not unusual for them to hover around 120-220 Mbps. If they do reach max speed, it can take a while - slow ramp up.

I could be experiencing a situation where the servers I am downloading from do not have sufficent capacity, but given that the fact that speedtests also highlight the same thing I am thinking it is not the issue. Perhaps the slow ramp up may be caused by web server configuration to deal with the load.

I've gone through basically all what Zen have asked me to do, and then some. Stuff like using their supplied router with the Openreach modem. I've done more, such as trying two different modems, three routers, multiple wired and wireless devices, different browsers, getting results no different.

They have recently sent an engineer out who technically did not find a fault at all (which is what I was expecting) but Zen did not want to change backhaul until this had been done. There was a minor balance issue which did not quite meet the fault threshold, but since having that fixed the downstream attainable rate is looking a bit happier.

Before:
Code: [Select]
xdslctl info --stats
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:    0
Last initialization procedure status:   0
Max:    Upstream rate = 61552 Kbps, Downstream rate = 338781 Kbps
Bearer: 0, Upstream rate = 50005 Kbps, Downstream rate = 330011 Kbps

Link Power State:       L0
Mode:                   G.fast Annex A
TPS-TC:                 PTM Mode(0x0)
Trellis:                U:ON /D:ON
Line Status:            No Defect
Training Status:        Showtime
                Down            Up
SNR (dB):        3.6             7.5
Attn(dB):        31.0            0.0
Pwr(dBm):        0.0             3.9

After:
Code: [Select]
xdslctl info --stats
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:    200000
Last initialization procedure status:   0
Max:    Upstream rate = 61789 Kbps, Downstream rate = 344897 Kbps
Bearer: 0, Upstream rate = 50005 Kbps, Downstream rate = 330011 Kbps

Link Power State:       L0
Mode:                   G.fast Annex A
TPS-TC:                 PTM Mode(0x0)
Trellis:                U:ON /D:ON
Line Status:            No Defect
Training Status:        Showtime
                Down            Up
SNR (dB):        4.1             7.6
Attn(dB):        31.0            0.0
Pwr(dBm):        0.0             4.0

Either way, here is one of the TBB speedtests:
(https://www.thinkbroadband.com/_assets/speedtest/button/1558699218235714455.png)

Perhaps even if you are not on G.fast but are on Zen with one of their "Fibre" products, you could share you experience of single-thread performance. Would be much appreciated, especially if you were able to resolve the issue if you had one since it is something I wish to do.

I would also like a second opinion on the provided TBB speedtest since I believe it to be indicative of some problem in their network - what do you think? I was under the impression such single-thread performance could mean there is an issue with backhaul.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: Chrysalis on May 24, 2019, 03:59:07 PM
its been a complaint with zen that comes up every now and then, although in your case the speed isnt terrible at least and should be ok for all streaming services.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: re0 on May 24, 2019, 04:46:56 PM
I've been reading that about Zen. There were quite a few threads on TBB relating to the issue over the past few years and prior.

While I would agree it should be okay for streaming services, it's just a bit annoying when downloading files. I don't consider it to be performing good in that respect.

Another issue with Zen I've had so far is routing - it's annoying that my traffic always gets routed Manchester first then London. Other ISPs in the area have latency ~10ms to London-based servers, but on Zen I seem to be getting an extra 10-15ms.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: re0 on June 05, 2019, 02:58:15 PM
I consider the problem seemingly resolved after the faults team have routed me to London, which I have been told will remain. Apparently being routed to Manchester in the first place was an "error".

(https://www.thinkbroadband.com/_assets/speedtest/button/1559741540781715255.png)

Single-thread speeds have dramatically improved, and multi-thread speeds are more consistent. This is all good news for me.

Furthermore, good has also come out of this for the latency since it's now dropped by 10ms, so London is 12ms now and servers further afield have reduced latency for me. It's not quite 10ms as I had previously, but I'll take it. ;D
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: kitz on June 06, 2019, 11:17:11 AM
Quote
but Zen did not want to change backhaul until this had been done.

afaik they use BTw's Shared WBMC for their g.fast backhaul services - even if they have an 'LLU' presence in the exchange for ADSL & FTTC.   
It will obviously enter one of their gateways at some point ie Manchester or London... so it depends on how much capacity they have on their gateway host link (https://kitz.co.uk/adsl/wbc_wbmc.htm#WBMC_shared) which will be taking feeds from multiple g.fast connections around the UK.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: kitz on June 06, 2019, 11:31:45 AM
Quote
Furthermore, good has also come out of this for the latency since it's now dropped by 10ms

Glad that swapping the gateway improved things for you. :) 
Totally unsure how many g.fast connections that Zen have, but at a guess I bet that the majority of them are coming off at Manchester as most (if not all) of their trialists were around the Manchester area.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: re0 on June 06, 2019, 12:02:23 PM
I don't think Zen has unbundled my exchange anyway. To my knowledge, it's only Talk talk and Sky who have LLU presence (which is not unusual to see).

It was just frustrating that the support initially told me that I would have to keep getting a new PPP session until I got London, which never happened when I tried. I don't know if that implied that I was bound to Manchester.

I can't really speculate about that since all I know is that it was just an error that they routed my connection to Manchester. As long as it stays with London, I have no issue.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: GeorginaWC on June 07, 2019, 01:25:28 PM
Your speeds look like you lucked out a bit. I've seen far worse.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: kitz on June 07, 2019, 02:14:13 PM
Quote
It was just frustrating that the support initially told me that I would have to keep getting a new PPP session until I got London, which never happened when I tried. I don't know if that implied that I was bound to Manchester.

That's the way things worked historically for their WMBC adsl services. You just kept trying to get a new PPP session on a London PoP. 

Not sure about their unbundled exchanges and g.fast though. 
Reading between the lines they purchased a brand new host link for their g.fast trialists - of which all were based around the Manchester area -  so I suppose it is possible that by default those were bound to their Manchester PoP.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: kitz on June 07, 2019, 02:23:59 PM
Quote
I don't think Zen has unbundled my exchange anyway.

Just a note - It is the headend not local exchange when it comes to FTTC and g.fast.   
I do have a partial but not complete list of which exchanges they had unbundled up to about a year ago.
I believe they were aiming to unbundle most of the headend exchanges in England - although saying that, my headend exchange is not on the list I have.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: re0 on June 07, 2019, 03:46:25 PM
Your speeds look like you lucked out a bit. I've seen far worse.
Possibly. I don't expect perfection, but with single-thread speeds are attaining 1/4 in speedtests consistently then you know something is up. Now it's closer to 4/5 most of the time, which is good enough.

That's the way things worked historically for their WMBC adsl services. You just kept trying to get a new PPP session on a London PoP. 

Not sure about their unbundled exchanges and g.fast though. 
Reading between the lines they purchased a brand new host link for their g.fast trialists - of which all were based around the Manchester area -  so I suppose it is possible that by default those were bound to their Manchester PoP.
On Plusnet (WBMC) I don't recall having anything above about 14ms to London - unless DLM shoved interleaving on on ADSLx. That seems to indicate that it was likely always connecting to London PoP(s). Perhaps the route may have deviated slightly. Though this was some years ago, so I don't remember exactly - and I don't remember if it was shared or dedicated WBMC at the time.

Just a note - It is the headend not local exchange when it comes to FTTC and g.fast.   
I do have a partial but not complete list of which exchanges they had unbundled up to about a year ago.
I believe they were aiming to unbundle most of the headend exchanges in England - although saying that, my headend exchange is not on the list I have.
Same for the presumed headend - no Zen.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: kitz on June 07, 2019, 07:02:04 PM
Quote
On Plusnet (WBMC) I don't recall having anything above about 14ms to London

All of Plusnet's PoPs are in London.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: re0 on June 07, 2019, 10:29:22 PM
Ah that would make sense then. :) To be honest, I don't remember the details.

Anyway, I think the problem is resolved here with the issues of speed, and latency is better as well. Any deviation in latency on each PPP session is just slight changes in routing.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: CarlT on June 10, 2019, 06:27:36 PM
Zen plan to unbundled every exchange with an NGA headend.

They have at least 400 exchanges unbundled covering 55% of NGA premises and are currently unbundling another 50 to provide 65% coverage. Will be at 700 exchanges and 80% by 2021.

They are also modifying their network so that entitling doesn't have to go through London or Manchester.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: re0 on June 10, 2019, 07:16:56 PM
I have read about this. I think my geographical location is set to be covered in(?) Q2.

Anyway, routing to London is good enough for me to be quite honest.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: adslmax on July 16, 2019, 06:33:00 PM
Before:
Code: [Select]
xdslctl info --stats
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:    0
Last initialization procedure status:   0
Max:    Upstream rate = 61552 Kbps, Downstream rate = 338781 Kbps
Bearer: 0, Upstream rate = 50005 Kbps, Downstream rate = 330011 Kbps

Link Power State:       L0
Mode:                   G.fast Annex A
TPS-TC:                 PTM Mode(0x0)
Trellis:                U:ON /D:ON
Line Status:            No Defect
Training Status:        Showtime
                Down            Up
SNR (dB):        3.6             7.5
Attn(dB):        31.0            0.0
Pwr(dBm):        0.0             3.9

After:
Code: [Select]
xdslctl info --stats
xdslctl: ADSL driver and PHY status
Status: Showtime
Last Retrain Reason:    200000
Last initialization procedure status:   0
Max:    Upstream rate = 61789 Kbps, Downstream rate = 344897 Kbps
Bearer: 0, Upstream rate = 50005 Kbps, Downstream rate = 330011 Kbps

Link Power State:       L0
Mode:                   G.fast Annex A
TPS-TC:                 PTM Mode(0x0)
Trellis:                U:ON /D:ON
Line Status:            No Defect
Training Status:        Showtime
                Down            Up
SNR (dB):        4.1             7.6
Attn(dB):        31.0            0.0
Pwr(dBm):        0.0             4.0

Hi re0

I am going live soon with Zen Internet with commited date of 30th July 2019 with G.fast & line only from PN. Don't mind asked you where can I get these stats from? Is it from Zen sending out fritz!box 7530 to me next few days for free of charge along with Engineer to bring Openreach Modem MT992. Or do I need to buy a G.fast modem same as you?
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: j0hn on July 16, 2019, 08:18:21 PM
You will be provided a locked MT992, no stats at all.

The Fritzbox is used as a router, there is also no stats.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: adslmax on July 16, 2019, 09:04:19 PM
 :no: Pretty stupid of Openreach to hidden these important stats, Bloody BT.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: re0 on July 16, 2019, 09:35:49 PM
Don't mind asked you where can I get these stats from? Is it from Zen sending out fritz!box 7530 to me next few days for free of charge along with Engineer to bring Openreach Modem MT992. Or do I need to buy a G.fast modem same as you?
ZyXEL XMG3927-B50A for these stats. There are a quite a few modems about, but virtually no UK availability as of present.

You should be able to access very limited line data on the Zen portal (more information here (https://support.zen.co.uk/kb/Knowledgebase/Troubleshoot-Check-your-Fibre-Optic-Broadband-line-rate)), but I don't use it.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: adslmax on July 16, 2019, 09:58:02 PM
ZyXEL XMG3927-B50A for these stats. There are a quite a few modems about, but virtually no UK availability as of present.

You should be able to access very limited line data on the Zen portal (more information here (https://support.zen.co.uk/kb/Knowledgebase/Troubleshoot-Check-your-Fibre-Optic-Broadband-line-rate)), but I don't use it.

The line data via zen will not show any max rate only the sync rate. Oh well I have emailed AA Isp to see if I can purchase ZyXEL XMG3927-B50A off them, wait and see.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: dee.jay on July 19, 2019, 08:34:38 AM
:no: Pretty stupid of Openreach to hidden these important stats, Bloody BT.

Heh, they are hidden for a very good reason, I'd suspect!
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: Alex Atkin UK on August 29, 2019, 10:30:48 PM
The line data via zen will not show any max rate only the sync rate. Oh well I have emailed AA Isp to see if I can purchase ZyXEL XMG3927-B50A off them, wait and see.

In my experience it hasn't updated since 2015, my line rate is WAY slower than it was back then.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: fat jez on August 29, 2019, 10:34:16 PM
The annoying thing is I believe Zen have access to actual line sync rates, not sure if they get SNR. Last time I spoke to them, I suggested showing them on the customer portal would be useful.
Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: flilot on August 30, 2019, 12:18:21 PM
The annoying thing is I believe Zen have access to actual line sync rates, not sure if they get SNR. Last time I spoke to them, I suggested showing them on the customer portal would be useful.

The sync rates reported in the Zen portal seem to differ from actual sync rates.  See images below; sync rate reported by the portal for my FTTC line is 67401, as reported by my modem it's 67603.  Strange.

Title: Re: Anybody on Zen G.fast? Poor single-thread downloads.
Post by: fat jez on August 30, 2019, 04:29:11 PM
The sync rates reported in the Zen portal seem to differ from actual sync rates.  See images below; sync rate reported by the portal for my FTTC line is 67401, as reported by my modem it's 67603.  Strange.

Yes, they do. The Zen tech support person told me my line was syncing at 375Mbps, which is very different to the 312 the portal reports for my line.