You are right - thanks. The line went down again this morning and I checked the transceiver stats before rebooting. The downlink noise margin was 0.-3 (sic) when it usually is around 6. After rebooting it was back to 6.
Thankyou for the help.
So, I called Verizon when the link was down and after about 20 minutes of testing they declared that there was a problem between the c/o and my house. "Yes" I said. They started a trouble ticket and declared it closed, by phone call, about 12 hours later. The following morning, the line was down again. So, yesterday morning, I called to reopen the trouble ticket - that's hard becasue the phone staff are trained on the assumption that every call is a new problem. We went through all the troubleshooting again during which they found that I had no problem because the line was working (here is the secret that they wouldn't hear: I fixed it by reboting the modem.) Yesterday evening a very polite young man called to say that they had started a 24 hour test of the line and this morning - about 14 hours later - they called to say that the trouble ticket was closed and the problem fixed. We'll see. So far, I have not been able to convince them that the test for an intermittent problem is not a 24-hour test but a 7 day test.
From a technical perspective, the noise margins on the down link are slightly higher, I think, closer to 7.5 rather than 6 where I mostly saw it, but I am not checking it every 5 minutes so don't have a very good picture of what is normal. We'll see. The customer staff are all very nice, follow the scripts and the follow up is good, but the attention to the technical problem is not half as good.
I'm typing with one hand and talking with Verizon in India as I type. The line went down again this evening and this very nice tech ws trying to diagnose a problem in my computer. Squelshed that idea, reset the line and now we are doing a line test - which won't show much since I rebooted the modem and fixed the problem. She has permission to open a trouble ticket at the c/o which - I predict - will complete a 24-hour line test in half that time, declare it solved and call me with that good news.
Now I am supposedly getting 24 hr line tests for several days (until Tuesday) and then they will contact me.
The modem is plugged in using the rj-45 cable that came with it and it is about 10 feet from the outside box as well as the first device on the line. The only way the modem could get closer to the outside box would be to park it on the lawn. The connection from the outside box to my distribution panel was done by professionals five years ago. I guess I'd believe in an internal problem if both up and down noise margins were bad, but my uplink is stable while the downlink margin is consistently lower (by 4-5 dB) and crashes every 12 hours or so. The uplink margin shows no variation at all. The fact that the crashes seem to coincide with sunrise/sunset makes me think that it is some device on a diurnal cycle between my house and the c/o or a device with a problem that crashes itself on a regular cycle.
Anyway, thanks for the ideas. I will double check the lines and makse sure that no spider is warming it's babies in the distribution box.
I think the problem is solved from an intellectual point of view - we know that the problem is a low noise margin on the down link. Now the problem remains conveying that through customer service to the c/o techs who can do something about it. Naturally, intermittent problems are the hardest to solve and the ones that the customer service can do least about. None the less, their scripts require them to do certain things in a certain order and it is not possible to actually solve the problem on the timescale apparently imposed by Verizon. Even the follow up calls, reporting the results of the 24 hour tests, seem to come before 24 hours have passed.
I am formulating a theory which runs along the lines that the customer's cost of complaining must at least equal the cost of Verizon's repair. If there is a physical line problem between the c/o and my house, my efforts/costs to get that problem resolved must be at least as high as the cost of fixing the line because any repair to infrastructure takes away from profits. It might make sense from a telco perspective but is not what I expect to be the responsibility of the telco in a commodity arena which esentially is monopolized by a few companies. If they own all the copper, they need to maintain it at a reasonable level of service. Similarly, ISPs can charge per MB when the serives is equivalent to power, gas and water. As long as the ISPs provide "up to x download speeds" they shouldn't be able to charge by consumption. Imagine if PEPCO promised up to 110V/50 Amps, or WASA up to 100 gallons of water a day. Their service is as much as I can use in a normal residence, and ISPs should be the same.
Back to the point, can we change the title to "unreliable DSL in Washington DC - problem identified but not fixed"?
You are right but the connection is generaly steady and then has periods, this is the longest one, when the service is unreliable. It has gone for months with no hiccups and then suddenly there is a period when it can't remain alive.
Yesterday we had a huge rainstorm and that did not bring the service down although it did lower the noise margin - on the downlink only - which reduces the chances that the cause is environmental. Yesterday I also started logging the exact time that the link went down, based on the logs. So far I've had three crashes since yesterday afternoon, 16:42, 05:31 and 08:37. Since the rains remain in the area and there are showers off and on, that may be a correlation though I still loose the link when it is completely dry.
We'll see. With any kind of luck the five day monitoring cycle will give the c/o staff something to work with.
Does not sound like a CO problem at all, sounds like it's in the lines. Even if you are only 10' from nid anything else on line can still interfere with it. See if you can plug directly into the nid. Have the techs ever done a pair change? That is change the pair of wires you are on to the CO with a spare pair. If not I would have this done first. If that doesn't help have the tech call the MCO dept. And have them run a MLT test to see how the line looks. Ask them if the multi notch setting is turned off, if not ask them to turn it off and see if the capacity and the noise margin increases or decreases. If it is better or the same, leave it off, if it's worse have them turn it back on. Then have them temporally turn you down to 1.5m and see how the capacity and the noise margin look then. I have had many DSLs work better and faster at 1.5m then 3m