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utlonghorn34

join:2012-12-20
Austin, TX

[Line Problem] Intermittent connectivity

Howdy y'all - I'm trying to sort out my folks' DSL connection in northern Alabama over the holidays.

The connection seems to drop in and out all day, every day. I've observed the problem with both their Netgear DGN2200 ADSL+/router device, and an old Speedstream 5260/5660 I've hooked up to test things. The overseas AT&T support desk confirms that IP connectivity is coming up and down all day, but apparently they have no way to access historical line quality information? (ie: you have to call them while the circuit is dead?) They're sending out a guy (on Christmas Eve, whoa!) to have a look at the box outside tomorrow, but figured I'd start a thread here anyway.

The Speedstream modem seems to provide much more detailed information about the failures as they happen.

On the 5260/5660 ATM Statistics page:


AAL5 Statistics:
Transmit Receive
SDUs 180422 285695
Cells 507658 8372901
Octets 20206982 398118127
Errors 72 0
Discards 72 762
SAR Timeouts 0
CRC Errors 753
Oversized SDUs 0 0


On the 5260/5660 DSL Statistics page:


DMT Statistics ATU-R ATU-C
Received Blocks
Transmitted Blocks
Corrected Blocks 0 0
Uncorrected Blocks 0 0



Failures ATU-R ATU-C
Loss of Framing 2 2
Loss of Signal 13 15
Loss of Link 14 14
Loss of Power 0 0
Errored Seconds 14 18



15-minute Interval Statistics ATU-R ATU-C
No. of 15-min Intervals with Data 8 8
No. of Intervals with no Data 88 88
Elapsed Seconds in Interval 278 278
Loss of Framing Seconds 0 0
Loss of Signal Seconds 4 2
Loss of Link Seconds 51 51
Loss of Power Seconds 0 0
Errored Seconds 4 3
Received Block Count
Transmitted Block Count
Corrected Block Count 0 0
Uncorrected Block Count 0 0
Current 1-day Statistics ATU-R ATU-C
Current Elapsed Seconds 6576 6576
Loss of Framing Seconds 11 12
Loss of Signal Seconds 26 21
Loss of Link Seconds 267 267
Loss of Power Seconds 0 0
Errored Seconds 39 44
Received Block Count
Transmitted Block Count
Corrected Block Count 0 11617
Uncorrected Block Count 650 512


The house (2003 construction?) is wired with two lines into every jack (inner/outer pair), separated by floor (ie: two pieces of CAT-5 that end up outside, apparently color-coded by floor - so there's probably a junction box for each floor that breaks out into circuits for the individual wall jacks).

At this point, the DSL modem is the only device connected to the house wiring, and only one pair of the downstairs wiring is connected to the BellSouth box outside. Picture of the wiring mess attached.

Any ideas from y'all, or perhaps things the AT&T guy might look for while he's out here?

Thanks in advance!

utlonghorn34

join:2012-12-20
Austin, TX

Ahhh, should probably include some of the SNR / line quality information, too:

When the DSL is down, the Speedstream reports "Defects detected" for ATU-R and ATU-c:


DSL Status
Cell Delineation False
DSL State Down

DSL Channel Info ATU-R ATU-C
Current TX Rate (bps)
Previous TX Rate (bps)
CRC Block Length
Interleave Delay
DSL Physical Layer Info ATU-R ATU-C
Current Attainable Rate 0 0
Current SNR Margin
Current Attenuation
Current Output Power
Current Status Defects detected
No Loss of framing detected
No Loss of signal detected
No Loss of power detected
No Loss of signal quality detected Defects detected
No Loss of framing detected
No Loss of signal detected
No Loss of power detected
No Loss of signal quality detected


While the DSL is working:


DSL Channel Info ATU-R ATU-C
Current TX Rate (bps) 512000 7360000
Previous TX Rate (bps) 512000 7360000
CRC Block Length
Interleave Delay
DSL Physical Layer Info ATU-R ATU-C
Current Attainable Rate 512000 14431372
Current SNR Margin 7.5 23.0
Current Attenuation 20.0 11.0
Current Output Power 126.5 20.0
Current Status No Defects detected
No Loss of framing detected
No Loss of signal detected
No Loss of power detected
No Loss of signal quality detected No Defects detected
No Loss of framing detected
No Loss of signal detected
No Loss of power detected
No Loss of signal quality detected


As the DSL is flaking out, the ATU-R "current output power" drops to 0 and eventually back up to 119-126. The ATU-R SNR Margin value jumps all over the place, too - it went up to 120 or so the last time the connection dropped (before stabilizing between 7 and 9 when the connection came back up).


utlonghorn34

join:2012-12-20
Austin, TX

Click for full size
And a screenshot of the status page as the connection is flaking out...

jc3116
Premium
join:2003-01-03
Snellville, GA
reply to utlonghorn34

Disconnect the blue cat 5 wire (looks like an alarm wire, in on the O-W and back out on the Bl-W). Connect the Bl-W pr on the white cat 5 wire and get rid of the duct tape splices. You should also check your modem stats at the entrance bridge (the grey cover) and compare them to the inside stats.
The dsl tech has probably done this provided he actually came out today.

Merry Christmas.


utlonghorn34

join:2012-12-20
Austin, TX

So the AT&T guy was really helpful - he quickly confirmed that the signal loss was on the house side of things; he also said he was hearing the DSL modem - orange and orange/white pair - on the blue blue/white pair in the same cable jacket (crosstalk).

I pulled off every phone outlet cover in the house, and found that in one outlet, orange/white was shorted onto blue/white... probably not helping things. They'd also untwisted the pairs 7-8" back in *every* outlet.

The AT&T guy also explained that most homes are daisy chained, jack to jack, and not central patch panel style like I'd assumed (based on my initial survey of two wall jacks). Sure enough, jacks were daisy chained onto each other, sometimes very poorly. Went through one by one and eliminated all the unnecessary terminations on the pair attached to the DSL modem. The white-jacketed Cat5 cable entering the NID outside was apparently a dedicated alarm system circuit; the AT&T guy cut off the splices - splicing the white Cat5 b/b&w pair onto the blue Cat5 b/b&w pair - and that helped things, too.

Seems like things are working properly now!

ADSL Link Downstream Upstream
Connection Speed 8128 kbps 509 kbps
Line Attenuation 20.5 db 10.2 db
Noise Margin 28.6 db 23.2 db

Thanks for the reply jc3116, and kudos to AT&T for having knowledgeable folks out in the field!

Merry Christmas!