Broadband Related > ISPs
Anybody on Zen G.fast? Poor single-thread downloads.
re0:
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: ---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
--- End code ---
After:
--- Code: ---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
--- End code ---
Either way, here is one of the TBB speedtests:
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.
Chrysalis:
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.
re0:
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.
re0:
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".
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
kitz:
--- Quote ---but Zen did not want to change backhaul until this had been done.
--- End quote ---
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 which will be taking feeds from multiple g.fast connections around the UK.
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