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[displaced]

We had a power cut about 8.40pm last night.  After everything came back up, I saw some interesting stuff on the HG612's stats page and MDWS.

Previously, I'd been getting an attainable of ~49/50Mbit, and syncing at between 1 and 3Mbit above attainable.  Line was solid - no resyncs, almost 0 ES on downstream, 30-40 ES on upstream.

After the powercut, my attainable's about the same but my downstream sync speed has leapt up to 57Mbit (and upstream's gone from about 9Mbit to 16Mbit!). 

My SNRM's also showing as 3.8/2.3.  Errored seconds still look OK-ish, probably on track to be a little higher than before, but nothing insane.

[roseway]

That's a fairly common experience after a power cut. If your modem is one of the first in your locality to reconnect when the power comes back, there will be fewer crosstalk disturbers initially, so it will connect at a higher than normal speed. A bit later, other users come back, increasing the crosstalk and reducing your SNRM. If you're lucky it will remain stable under these conditions and you can enjoy the higher speed until the next time you reboot or a resync occurs.

To answer your question, no, I don't think you're on a 3 dB target. If you look at my stats on MDWS you'll see that I've currently got an uptime of 46 days under the same conditions, and for the same reason.

[skyeci]

Sounds like early sync compared to your neighbours etc.. keep on an eye on your attainable. If it starts to drop below your sync you will start to see the effects of cross talkers on your line...

edit - looking at your max attainable its well below your sync. 57 sync with attainable at 49mb

[displaced]

Thanks, both -- that explanation makes sense.  Hooray for fast-syncing HG612s!

My situation does seem very similar to yours, roseway.  I'll be very interested to see how the ES and SES figures change over the next few days. 

I always had very low ES and zero SES.  Whilst browsing around MWDS, I saw plenty of people with higher ES with perfectly stable lines, so I always wondered if there was some headroom on my line, regardless of the attainable figure.  I suppose this is the perfect test! 


[edit - worst case, I'll start resyncing lower -- but that might help us figure out for certain whether Vodafone use the Speed or Standard profile]

[andyfitter]

I had something very similar happen a few nights ago. My sync and attainable are normally both around 77. Brief power failure around 2am and my HG612 came back up at around 79.5/79.5 sync/attainable.

It's holding quite well at that level, with a snrm of about 5.5. I understand why the rates were initially higher as my HG612 was one of the first to resync, but what I don't understand is why my attainable hasn't dropped back to roughly where it was before, bearing in mind that I would have thought all the other people who were affected by it would be back online after two days?

Any thoughts? (User andyf on MDW)

[j0hn]

definitely doesn't sound like a 3dB target, as it would only be on the downstream. looks like you've simply reconnected before all your crosstalkers.

[displaced]

So, the ES rate doesn't look pretty, and I've had my first ever 'natural' (i.e., not caused by an OR engineer monkeying with the line) bunch of SES's.

Just wondering what DLM action will look like.  Does it say "Hey, you're too unstable -- resync!" - basically equivalent power-cycling the modem, or is there a risk that the DLM might actually adjust some property of the line to cause a greater intervention?

Essentially, am I better-off long-term to just reboot it now?

[roseway]

Looking at MDWS it appears that you've only had 2 SES's in the last 24 hours, and your ES figures are unremarkable, so it doesn't look to me as though you're in imminent danger of DLM action.

When DLM does act, it doesn't just force a resync, it makes some adjustment first. In fact, resyncs are part of its assessment of the stability of the connection. But as I say, your connection looks OK to me.