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Standard User olicuk
(learned) Wed 13-Jan-16 23:14:48
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Any suggestions on FTTC dropout?

[link to this post]

My local cabinet was enabled for FTTC in early December and I was connected on 23rd. I'm around 300-400m from the cabinet, and have the Zen 80/20 service.

My initial connection speed has been good (appreciate things may get worse as more people are connected), the Zen portal reports my earlier connections as follows:

Upstream Downstream Sync Rate BRAS Profile Interleave Sync Date Date
19999 75475 77974 TR101 Auto 03-Jan-2016 19:01 03-Jan-2016 19:01
19999 74467 76933 TR101 Auto 28-Dec-2015 02:08 28-Dec-2015 02:08
19056 76912 79459 TR101 Auto 23-Dec-2015 14:00 23-Dec-2015 14:00
18837 77435 79999 TR101 Auto 23-Dec-2015 13:28 23-Dec-2015 13:28
19999 69821 72133 TR101 Auto 23-Dec-2015 13:00 23-Dec-2015 13:00

... and speed tests have aligned with that. Since late December I've been using the TBB BQM and as far as I can tell, my connection until the 10th Jan was good, eg/

Mon 4th Tue 5th Wed 6th Thur 7th Fri 8th Sat 9th

Then at about 4:30am on Sunday (10th) there appears to have been a forced re-sync, and presumably DLM added interleaving as the latency increased from around 11ms to 20ms:

Sun 10th - Interleaving?

First question, any way to work out why, as packet loss appears to have been low and the line stats good before that?

Monday and Tuesday seemed back to a normal apparent good connection, but at the higher latency. The number of dropped packets after 8pm until just after 10pm looked slightly higher, but nothing major.

Then today I've had this:

BQM Wed 13th - UGH!

From around 2am to 3am lots and lots of resets I presume? And then the connection fell over completely. At about 6:30am I woke up, found the internet was down, and my router was lit up like a Christmas Tree (I have a Draytek Vigor 130 VDSL modem, and have been using my old Draytek Vigor 2820vn router with it - the 2820 basically had basically all of it's grid of LEDs on!).

Having not looked at the BQM at the time, I switched off the router for a minute and switched it back on again; I didn't touch the modem. This looks to have been a bad idea, as it looks from the graph like there was another troublesome hour of re-syncs, and then the router keeled over again. Certainly internet access over that hour was patchy which seeing the graph is understandable!

When I got home I turned everything (modem, router, and the gigabit switch connected to it, and a few other networked devices) off for 30 mins, then turned it back on. The connection looks to be good again now, but doing speed tests and checking the line connection stats in the Zen portal it looks like the download sync rate has dropped significantly (by ~17Mbps)...

Upstream Downstream Sync Rate BRAS Profile Interleave Sync Date Date
19999 58625 60566 TR101 Auto 13-Jan-2016 17:26 13-Jan-2016 17:26
19999 75475 77974 TR101 Auto 03-Jan-2016 19:01 03-Jan-2016 19:01

Is today's problem likely just caused by my modem or router having a bad day and falling over? Is the sync speed likely to be hit long term... reading about DLM for example, it appears to effect changes overnight so would it have caused the sync to drop so much today? What's the best (least likely to cause further damage) way to see if the sync speed will go back higher?

I can't easily get to the Draytek modem stats but when I looked at them in late December they were:

VDSL Information: VDSL Firmware Version:05-04-08-00-00-06
Mode:17A State:SHOWTIME TX Block:0 RX Block:0
Corrected Blocks:0 Uncorrected Blocks:0
UP Speed:20000000 Down Speed:77364000 SNR Margin:6 Loop Att.:15

---------------------- ATU-R Info (hw: annex A, f/w: annex A/B/C) -----------
Running Mode : 17A State : SHOWTIME
DS Actual Rate : 77364000 bps US Actual Rate : 20000000 bps
DS Attainable Rate : 77410560 bps US Attainable Rate : 30167000 bps
DS Path Mode : Fast US Path Mode : Fast
DS Interleave Depth : 0 US Interleave Depth : 0
NE Current Attenuation : 15 dB Cur SNR Margin : 5 dB
DS actual PSD : 7. 0 dB US actual PSD : 13. 5 dB
NE CRC Count : 0 FE CRC Count : 0
NE ES Count : 0 FE ES Count : 0
Xdsl Reset Times : 0 Xdsl Link Times : 1
ITU Version[0] : b5004946 ITU Version[1] : 544e0000
VDSL Firmware Version : 05-04-08-00-00-06
Power Management Mode : DSL_G997_PMS_L0
Test Mode : DISABLE
-------------------------------- ATU-C Info ---------------------------------
Far Current Attenuation : 0 dB Far SNR Margin : 15 dB
CO ITU Version[0] : b5004244 CO ITU Version[1] : 434da48c

Grateful for any comments/suggestions/answers! Many thanks!

Administrator MrSaffron
(staff) Wed 13-Jan-16 23:20:12
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Re: Any suggestions on FTTC dropout?

[re: olicuk] [link to this post]
Errors on the VDSL2 segment that the DLM system can see may not have a massive impact on the BQM since VDSL2 can often recover quickly enough to just show as a little bit of jitter

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User olicuk
(learned) Wed 13-Jan-16 23:31:41
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Re: Any suggestions on FTTC dropout?

[re: MrSaffron] [link to this post]
Thanks Andrew

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