Sudden upload bandwidth drop

[JamesAllen]

Hi guys,

From the lack of posts I assume no one else has suddenly experienced a massive drop in upstream bandwidth today? My usual 0.95 or is fluctuating between about 0.10 and 0.3. I do a live radio show every Friday and I've just had to stop it as I kept losing connection. It's not with the stream provider as a bandwidth test is showing the upstream is screwed (along with my web cam feed failing). Some tests would fail on the upstream. They are fine on downstream and the ping is normal at 40ms or so.

I had this kind of issue in April 2011 (http://www.idnetters.co.uk/forums/index.php/topic,25336.0.html) where upstream just seemed to drop massively but I was told that wasn't possible if downstream was fine. Something is certainly wrong here though. In the previous case the problem went after a few days.

The last time it happened I switched to another router I had and the problem still remained.

It's nothing else on my network as I know exactly what is running.

Any ideas?

[Bill]

Long shot- have you tried a new filter?

[JamesAllen]

Hi Bill,

Not a bad suggestion, although I remember trying that last time and unfortunately it didn't sort it.

However, I have just done another speed test and everything is looking back to normal again. Upstream benching at 0.92.

I'd love to know what caused the hours of low and inconsistent performance.. :|

[Lance]

Do you know what your upstream sync was at the time?

[JamesAllen]

Hi Lance,
That's the thing with this issue. Sync speeds and noise margins were all normal. I had something like 1150 on the upstream. I rebooted the router as well just to be sure.

It feels just like it did in April. Very bizarre. Ping fine, downstream fine, upstream mangled. With the speed test, it would actually fail on some tests with an error.

Would love to know where this problem lies..

[Bill]

I had a couple of other thoughts after I'd knocked off last night...

1) I'm not clear whether it's just one machine or all of them on your LAN, if it's just one could there be a problem with your network card or cable?

2) With ADSL the upstream is handled by the low frequencies, istm that it's at least feasible for a source of low-frequency interference to upset the upstream without affecting the downstream. Perhaps someone with more technical knowledge than me would like to comment on that and, if it is possible, how you might go about proving/finding it? As it would be LF, I doubt that the old trick of a de-tuned AM radio would work.

[JamesAllen]

The issue was with all of my machines on the LAN so definitely not a network card - though I had the same thought when it was happening.

The interference thing is very interesting though. I didn't realise upstream could be affected like that separately. Could be something in that. Though like you say, quite hard to identify.

Done another speed test this morning and everything is looking normal again. Weird and annoying that it seems to occur on a Friday - it did back in April, again putting a stop to my radio show.

[Rik]

What happens if you disconnect all the other machines?

[JamesAllen]

I didn't try in this instance but the last time I had the same issue I disconnected all but my desktop and it didn't go away.

[Rik]

In that case, try disconnecting your desktop and all but one other. It's possible a power supply is giving off noise.

[JamesAllen]

Ah that's not a bad idea. Everything has gone back to normal now though, but a good test if this reoccurs.

Just bizarre that is happened the same way last April on a Friday and then again yesterday. All to return to normal the next day (well actually late last night).

Interference is something to keep in mind. Though it must be very intermittent.

[JamesAllen]

Hi guys,

Well after this problem resolving itself I've just had it happen again while streaming a replay of my radio show. Started about 5 mins ago.

Here are detailed stats from my router. Anything jump out?


/usr/sbin/adslctl: ADSL driver and PHY status
Status: ShowtimeRetrain Reason:   8000
Channel: FAST, Upstream rate = 1197 Kbps, Downstream rate = 14752 Kbps
Link Power State: L0
Mode:         ADSL2+
Channel:      Fast
Trellis:      U:ON /D:ON
Line Status:      No Defect
Training Status:   Showtime
      Down      Up
SNR (dB):   7.1      6.5
Attn(dB):   25.5      11.2
Pwr(dBm):   0.0      12.8
Max(Kbps):   17900      1220
Rate (Kbps):   14752      1197
         G.dmt framing
K:      231(0)      28
R:      16      8
S:      1      8
D:      64      4
         ADSL2 framing
MSGc:      59      10
B:      230      27
M:      1      8
T:      2      6
R:      16      8
S:      0.5000      5.9487
L:      3952      312
D:      64      4
         Counters
SF:      15508724      14824765
SFErr(CRCErr):   294      0
RS:      2016134244      1854394
RSCorr:      20307723      0
RSUnCorr:   7483      0

HEC:      264      0
OCD:      4      0
LCD:      0      0
Total Cells:   178348008      2032119
Data Cells:   211688592      391649
Drop Cells:   0
Bit Errors:   0      0

ES:      202      0
SES:      0      0
UAS:      39      0
AS(Uptime):   252022

INP:      1.03      0.41
PER:      16.25      17.84
delay:      8.00      5.94
OR:      32.00      7.17

Bitswap:   6824      94
Total uptime:   252022

Total time = 1 days 22 hours 1 min 25 sec
SF  = 15508724
CRC = 294
LOS = 0
LOF = 0
ES  = 202
Latest 1 day time = 22 hours 1 min 25 sec
SF  = 4878962
CRC = 89
LOS = 0
LOF = 0
ES  = 67
Latest 15 minutes time = 1 min 25 sec
SF  = 5246
CRC = 0
LOS = 0
LOF = 0
ES  = 0
Previous 15 minutes time = 15 min 0 sec
SF  = 55427
CRC = 2
LOS = 0
LOF = 0
ES  = 1
Previous 1 day time = 24 hours 0 sec
SF  = 5316826
CRC = 99
LOS = 0
LOF = 0
ES  = 70
15 minutes interval [-30 min to -15 min] time = 15 min 0 sec
SF  = 55366
CRC = 0
LOS = 0
LOF = 0
ES  = 0
15 minutes interval [-45 min to -30 min] time = 15 min 0 sec
SF  = 55366
CRC = 0
LOS = 0
LOF = 0
ES  = 0
15 minutes interval [-60 min to -45 min] time = 15 min 0 sec
SF  = 55427
CRC = 0
LOS = 0
LOF = 0
ES  = 0
Showtime Drop Reason:   8000
Last Retrain Reason:   8000

[Rik]

Nothing obvious, to me at least.

[JamesAllen]

Thanks Rik. Things are still not right now. The show has ended but a speed test still shows the upstream is low. Not sure what else to test.

BTW, on Friday I did a speed test not long after with just my home entertainment PC on and it was still showing low upstream then so not sure it is interference.

Very frustrating and worrying for when I next go live.

[JamesAllen]

I'm not sure if this means anything. But running the pingtest here: http://pingtest.net/ it is unable to determine packet loss, though ping at 32ms and jitter at 1ms looks good.

Could someone confirm that they see packet loss results. Thanks.

**EDIT: Scrub that - I just had to enable Java. The results are 1-3% packet loss.

**EDIT 2: Looks like downstream is getting bad now as well. Down to 3.5mb whereas it's normal 12mb. Something is seriously wrong here.

**EDIT 3 (): Downstream is back to normal but upstream is still not right.

[JamesAllen]

And without any changes, come 22:30 things are all back to normal with upstream at 0.99 again..

This is such a weird issue but seems to come on close to 6pm and ends after 10pm..

Also, with the upstream back to normal using pingtest shows 0% packet loss.

So something is certainly wrong somewhere.. Just not sure how to track it down..

[pctech]

At a pure guess this sounds like exchange congestion and unfortunately the only thing you could ask to do is for IDNet to put you on the Telefonica LLU service If O2/BE have a presence at your exchange http://www.samknows.com/broadband/broadband_checker

[JamesAllen]

Hi pctech,

Ah that is something I'd hope it wasn't but with the time frame it does look like it could be doesn't it. Thing is, I've had the connection for years now and never really had a problem apart from last April on a Friday when it happened. Happening again last Friday was a strange coincidence around the same time frame - though maybe coming on towards 7pm. Having it happen again tonight is very concerning.
I do need to find out for sure by a week on Friday as I have another radio show and it's really worrying to face problems during a broadcast.

With the top IDNet product, don't we get exchange priority though? Would that not minimise contention issues?

I'll have to ask IDNet support although when this happened last time I was told it's impossible for upstream to drop and downstream to be fine - which tends to be the pattern here.. Although today I did discover there was also packet loss and downstream suffered a few odd times (though not most of the time).

[pctech]

Big downloader/uploader moved in near you?

[JamesAllen]

Who knows.

Strange that this happened back in April for one day.. Now it's come back a year later. I need to resolve it though somehow as it totally stops me being able to broadcast.

[Glenn]

I know it's not a fix, but would FTTC be an option where you live?

[Bill]

I'm a Mac user so this suggestion may not be worth the drive space it takes up, but have you thought about running something like RouterStats Lite?

http://www.vwlowen.co.uk/internet/betatesters.htm

[JamesAllen]

@Glenn
That's a very good question actually. I was checking last night and FTTC should be enabled on the exchange in September. It's not close enough as I broadcast weekly, but it's a longer term solution even if the cost is higher.

@Bill
Ah yes, I ran routerstats a few years ago - must get that setup. The only thing is that is seems with this issue that all the router stats are correct. Noise margin when this happened was actual on the quiet side - i.e if I'd rebooted I would have synced higher and all other stats seemed normal.
Wonder if that gives more of an indication that the problem lies with congestion at the exchange.. hmmm.. I suppose I need to check every night this week to see if it is now a regular issue.

[Bill]

Wonder if that gives more of an indication that the problem lies with congestion at the exchange..

Sounds possible... maybe a local business doing an off-site backup?

No idea how you'd find out

[Bill]

Another thought- set up a tbb BQM?

http://www.thinkbroadband.com/ping

They can be tricky to interpret, but have the benefit of running 24 hours a day!