Selected ISP Support > Earthlink DSL > OK stats, but frequent loss of sync

reply to bk_856er

Re: OK stats, but frequent loss of sync

I received the Innoband 8860-C1 today and just set it up. The first impression is good and there were no glitches integrating it into my network. However, for some reason the modem is reporting 1.0/384 instead of my usual 1.5/384, with corresponding lower speed tests. Downstream attenuation is down (56dB) and downstream margin is currently 9dB. I'll update again with more details after I get some additional experience with the unit....

Bob

That's a bad sign. It should sync at the same rate as your other Modem. If you plug the other Modem back in, do you regain the 1.5 Sync Rate?

I'll swap modems tomorrow. I power-cycled the Innoband and now it syncs at 1.1/384. Weird. I'm no expert, but I assumed that the modem should sync with the DSLAM port setting, which according to a check by Covad just the other day was 1.5/384...

Thanks for confirming the proper sync behavior. Before I posted here I put an inquiry into Innoband with all the modem data and configuration, so we're on the same page. I see that you are a night-owl like me!

Slightly off-topic, but does anyone have an opinion of this Wilcom device?

»www.wilcominc.com/Item.cfm?ProdID=108

I currently use their PS-15S POTS wall-mount ADSL2+ splitter, but the "advanced filtering" claim of the DSL600-PS unit caught my attention. Maybe it would clean up my line a little and increase my downstream margin?

Bob

reply to bk_856er
Using the same "change to GDMT" trick that I used for the Zyxel modem, I was able to get my 1.5/384 sync back along with zippy downloads. I like this modem!

Set to ADSL2+ mode, the downstream attenuation was 52dB and the margin was 9dB and the modem synced at 1.0. With GDMT the values are different as displayed below. This is where I will keep things if everything remains stable. The attenuation makes me a bit nervous. The modem has options to tweak gains and other settings, which I will investigate later...

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Status
Device Information
Model Name 8860-C1
Host Name home.gateway
System Up-Time 18:29:49s
Current Time Fri, 10 Jul 2009 - 18:59:43
Hardware Version Solos-W ADSL-M v1.00
Software Version 5.52g.dk21.44

ADSL
Parameters
Connect Mode ADSL
Modulation G.Dmt
Profile Type COVAD
Activate Line true
Coding Gain auto
DSP Firmware Version E.25.41.44 A
Connected true
Operational Mode G.Dmt
Annex Type AnnexA
Upstream 384000
Downstream 1536000
CO Vendor GSPN
Elapsed Time 0 day 0 hr 7 min 39 sec

ADSL
Parameters
Downstream Upstream
SNR Margin 15.0 dB 23 dB
Line Attenuation 62.5 dB 31.5 dB
CRC Errors 2 0
Latency Fast Fast

Speakeasy Speed Test after change to GDMT
Download Speed: 1319 kbps (164.9 KB/sec transfer rate)
Upload Speed: 323 kbps (40.4 KB/sec transfer rate)

Sorry if you just saw your modem loose sync. I just provisioned your circuit to 3.0/384 because your had very good margins at 1.5/384.

Your margins came out to 3.0/384 @ 11.0db/23.5dB
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Statements made by me are not the views or practices of my employer and they cannot be held responsible for any statements I may make.

You the man! I was actually composing a post in the Covad Direct forum at the time to update you - thanks for your help on this! Keeping fingers crossed...

Bob

reply to e_dub

I only left the 3.0/384 port rated provisioned for 15 minutes. Long enough for me to check for errors and LOS.

Sorry but I can't leave the port provisioned at 3.0 unless there's an order change.
--
Statements made by me are not the views or practices of my employer and they cannot be held responsible for any statements I may make.

reply to bk_856er
If your line could maintain 11dB S/N at 3008 downstream, you would be stable at that speed. However, I don't think you're maintaining that margin, since you're losing sync.

Are you getting static on your phone? The description of the 'death spiral' sounds similar to an issue I had several years ago after a nearby lightning strike. I ended up with so much static on my line that voice was unusable and DSL was very slow. I reported the voice issue to AT&T and they eventually moved my line to a different cable pair.

e_dub: that's still great info to have - thanks! Is my next step to call up EL and request a 3.0 upgrade?

DrStrange: the thread/story here is sort of long so I will recap for you. A while back the original Zyxel modem at the default ADSL2+ settings started losing sync regularly. Investigation showed the fluctuating margins. Changing to GDMT mode totally stabilized the line. Tried a modern Innoband modem, and although it was stable set to ADSL2+, it only synced at 1.0/384. I changed the Innoband to GDMT mode and got 1.5/384 sync and rock-solid stability, which is where I am at right now. No more fluctuating margins and no more loss of sync.

As part of the original troubleshooting I sniffed the premises with an AM radio, relocated some components and wiring, monitored the margins, etc. None of that changed anything. The dial-tone has no static that I can discern. Something obviously changed or deteriorated a couple of months ago, when the Zyxel ceased to be stable at its default ADSL2+ settings, but I don't know how to track down that issue to resolve it.

Bob

reply to bk_856er
Ah, sorry. Senior moment.

I don't know if you'd notice static on LPV. I see you've done all the things I would have.

reply to bk_856er
Rather than push EL for 3.0 upgrade, I decided to monitor the line stats for a bit longer and keep some good notes. In my case the limiting parameter is the downstream S/N margin, which generally holds steady at ~15dB. According to e_dub's short test at 3.0 my downstream margin would be 11dB at that speed and basically good to go.

Here's an interesting observation. Thurs/Fri/Mon at exactly 9:00PM PST my downstream margin drops abruptly to ~9.5dB and stays like that for 2-2.5hrs. Then it returns just as abruptly to 15.5dB again. On Sat/Sun this did not occur, so I will tentatively assume it's a weekday thing. All other times of the day also seem to be fine. Line attenuation remains constant. Naturally the diminished margin would be killer on the sync at a higher speed of 3.0, and even at my current 1.5 speed I can see a large accumulation of CRC errors reported by the modem during the low margin period.

I have ruled out interference from within the premises. In fact, the only activity that induces a signal reduction is running the kitchen garbage disposal motor, which is about 15ft from the modem (15dB S/N down to 13dB S/N only while the motor is on). I still need to correlate the nightly line noise spike with possible neighbor activities, but does this pattern sound like something else, such as systematic maintenance on the line/equipment or??

The new modem has been great and the line stability (DMT mode!) and speed tests have also been very consistent. If nothing else, I now have a much better feel for the habits of my line.

Bob