Technical Discussion
  >> Technical Issues


Register (or login) on our website and you will not see this ad.


  Print Thread
Standard User zebb_edi
(newbie) Sat 19-May-18 10:30:51
Print Post

Long time to sync with exchange


[link to this post]
 
I've been having problems with my FTTC connection since January. Having been perfectly fine for a number of years it suddenly became very unstable and started dropping regularly overnight.

I am roughly 2km from the cabinet unfortunately so it's never going to be great.

I've now had 8 openreach engineers who originally found lots of battery on the line. They swapped connectors. They did a lift and shift, they swapped the line. They changed my E side to a different line. Initially there was battery on the line which seemed to go after changing things then come back for the next engineer. I think that's now resolved.

They recently messed with the profile and enabled interleaving which dropped my sync speed from ~20 Mbps to 12 Mbps but the line did stay connected for 4 days straight albeit with 55 million FEC errors and 113 CRC errors.

The last engineer then reset the profile and it jumped up to syncing at 17 Mbps. The handheld device they use shows no FEC or CRC and nor does my router initally whilst the engineer is here but then it appears at certain times it goes ballistic and unfortunately my line seems to be unstable again dropping out overnight. So of course whenever they are here they don't see the errors. My router reports far end stats but BT don't seem to be able to see those?

It seems like it's some sort of interference, but one thing that has started occurring since this fault is that it now takes an incredibly long time to actually sync with the exchange. It can be anything from 2 to 10 minutes. Several of the engineers couldn't actually get their devices to sync at all. The second to last engineer took 20 minutes to perform his close out test because his device kept timing out before it could complete it.

None of the engineers seem willing to investigate the slow syncing time though and just say some cards are slower than others. Does this seem normal to anyone else and is it possible it's contributing to the sudden drop in line quality?

If openreach's own tests can't complete easily then how can it be normal?
Administrator MrSaffron
(staff) Sat 19-May-18 12:07:55
Print Post

Re: Long time to sync with exchange


[re: zebb_edi] [link to this post]
 
If really 2km from the cabinet then a sync 20 Mbps was pretty amazing, 12 Mbps is still beyond expectations

VDSL2 can be slow to sync, but should be 2 or 3 minutes at worst, sounds like it may be having to go through extra permutations.

Solution is (a) someone pay for full fibre or (b) Banding via DLM to lower sync to a more regular 5 to 8 Mbps you'd expect at 2km

What modem are you using and which exchange/cabinet if a Huawei cabinet and not using a Broadcom chipset then switching to one may help

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User Zarjaz
(eat-sleep-adslguide) Sat 19-May-18 12:19:02
Print Post

Re: Long time to sync with exchange


[re: MrSaffron] [link to this post]
 
Yep, sounds like an unfeasibly high sync for the suggested D side length ?

I wonder if all this swapping of pairs has left the OP on an, in part, split pair ?


Register (or login) on our website and you will not see this ad.

Administrator MrSaffron
(staff) Sat 19-May-18 12:22:41
Print Post

Re: Long time to sync with exchange


[re: Zarjaz] [link to this post]
 
That is possible, but a split pair would make that sync even more amazing

I think vectoring can slow down the sync phase, and can imagine a vectoring engine will not enjoy a split pair, G.fast had a lot of work done to improve sync times i.e. the rare but long sync phase was a known problem with VDSL2

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User zebb_edi
(newbie) Sun 20-May-18 10:13:31
Print Post

Re: Long time to sync with exchange


[re: MrSaffron] [link to this post]
 
It's ~2km via the road, the line most likely goes slightly shorter route but I believe it's roughly that distance.

I'm using a DrayTek 2862. Had a DrayTek 2860 before and replaced it when the drops started happening to see if that resolved it. Also tried the openreach modem and that was much much worse.

The router is reporting it as a BDCM cabinet I believe.

The slow time to sync never used to occur, so I'm not sure if it's a cause or result of the problems i've been experiencing.

Unfortunately all phases of funding to improve the internet in the area have now finished and I've since discovered there's no further plans to upgrade anything in the area so i'm stuck unfortunately. Looking in to doing a community funded scheme with the local parish council currently.

---------------------- ATU-R Info (hw: annex A, f/w: annex A/B/C) -----------
Running Mode : 17A State : SHOWTIME
DS Actual Rate : 16888000 bps US Actual Rate : 1145000 bps
DS Attainable Rate : 17504268 bps US Attainable Rate : 1145000 bps
DS Path Mode : Fast US Path Mode : Fast
DS Interleave Depth : 1 US Interleave Depth : 1
NE Current Attenuation : 32 dB Cur SNR Margin : 4 dB
DS actual PSD : 12. 5 dB US actual PSD : 10. 5 dB
NE CRC Count : 132 FE CRC Count : 28217
NE ES Count : 50 FE ES Count : 24435
Xdsl Reset Times : 0 Xdsl Link Times : 17
ITU Version[0] : 00000000 ITU Version[1] : 00000000
VDSL Firmware Version : 07-07-09-05-01-07 [with Vectoring support]
Power Management Mode : DSL_G997_PMS_L0
Test Mode : DISABLE
-------------------------------- ATU-C Info ---------------------------------
Far Current Attenuation : 19 dB Far SNR Margin : 6 dB
CO ITU Version[0] : b5004244 CO ITU Version[1] : 434da48c
DSLAM CHIPSET VENDOR : < BDCM >

Edited by zebb_edi (Sun 20-May-18 10:15:22)

Standard User RobertoS
(elder) Sun 20-May-18 10:34:37
Print Post

Re: Long time to sync with exchange


[re: zebb_edi] [link to this post]
 
Check the DNS Server settings in your router are not 38.134.121.95

If they are, the links in this thread are relevant.

It seems Draytek routers are suffering from zero-day exploits changing the DNS Server addresses and some reports of drops like yours being caused.

My broadband basic info/help site - www.robertos.me.uk. Domains, site and mail hosting - Tsohost.
Connection - AAISP Home::1 80/20. 200GB. Sync 68940/13151Kbps @ 600m. BQMs - IPv4 & IPv6
Administrator MrSaffron
(staff) Sun 20-May-18 13:28:11
Print Post

Re: Long time to sync with exchange


[re: zebb_edi] [link to this post]
 
Lantiq based chipset but with vectoring and g.inp support so should be fine, don't recall if anyone has seen any improvement shifting from lantiq to a broadcom based modem/router that also has the vectoring and g.inp

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
  Print Thread

Jump to