07-31-2019 03:26 PM - last edited on 07-31-2019 04:11 PM by LawrenceC
I'm getting a lot of outages caused by the DSL modem doing retrains. The line itself isn't having a problem as far as I can tell. No noise on the voice line, performance is always good, and the retrains don't change the speed much (mostly twiddle the upload speed up and down just a little bit, or sometimes just do nothing). Three ways this causes a problem:
1) When the modem has been turned off for a while, it sometimes does a lot of retrains when turned back on, making it difficult to get much of anything done in the first half hour or so. Turning the modem off at night is a recent change that made the problem worse, but even when I used to leave it on 24/7 I was getting hammered by retrains, sometimes as many as 90 in a day, and numbers in the 130's were common after it had been up a few days. Not always - sometimes there would be none for a couple of days.
2) Retrains cause some applications to fail in a very inconvenient way. Worst example: I downloaded a 3+gb map update for a TomTom GPS, which requires using their download software. It has no decent recovery - just fails at every retrain, and I have to go back and restart it manually. It took three days of manually restarting it over and over before I finally got 4 1/2 hours continuous use with no retrain or other outage so it could finish.
3) Having the telephone ring has a high probability of causing a retrain. Worst example of why that's a problem: I needed to sign in to a bank account that calls on the phone with a security code that has to be typed in. The first three calls each caused a retrain, and lost the security code. It finally worked on the 4th try, but it wasted quite a bit of time, and I'm concerned that the bank might have a limit on the number of failed attempts and lock me out.
I have the modem data from this morning. After 21 retrains, mostly in the first hour and a half, the speed is exactly what it always is when the modem is first turned on. When I looked again 6 hours later, it had done 5 more, and changed the up speed to 832 instead of 864. The line SNR's shown below are typical - they don't change much. Does anyone have any ideas on why there are so many retrains, and how to get them to stop? Thanks.
Internet Service Provider: CONNECTING
PPP Parameter Status
User Name: vze1eu2wy
PPP Type: PPPoE
LCP State: UP
IPCP State: UP
Authentication Failures: 0
Session Time: 0 Days, 4H:2M:27S
Packets Sent: 104348
Packets Received: 103484
Broadband Parameter Status
Broadband Mode Setting: ADSL
Broadband Negotiated Mode: G.DMT
Connection Status: CONNECTED
Downstream Speed: 2944 Kbps
Upstream Speed: 864 Kbps
Retrain Timer: 0 Days, 0H:52M:11S
ATM QoS class: UBR
Near End CRC Errors Interleave: 5902
Near End CRC Errors Fastpath : N/A
Far End CRC Errors Interleave : 21064
Far End CRC Errors Fastpath : N/A
30 Minute Near End CRC Interleave : 315
30 Minute Near End CRC Fastpath : N/A
30 Minute Far End CRC Interleave : 0
30 Minute Far End CRC Fastpath : N/A
Near End RS FEC Interleave : 0
Near End RS FEC Fastpath : N/A
Far End RS FEC Interleave : 0
Far End RS FEC Fastpath : N/A
30 Minute Near End FEC Interleave : 1878
30 Minute Near End FEC Fastpath : N/A
30 Minute Far End FEC Interleave : 5
30 Minute Far End FEC Fastpath : N/A
30 Minute Discarded Packets Downstream : 0
30 Minute Discarded Packets Upstream : 0
SNR Downstream : 31 dB
SNR Upstream : 10 dB
Attenuation Downstream : 44 dB
Attenuation Upstream : 26 dB
Power Downstream 19 dBm
Power Upstream 11.9 dBm
Solved! Go to Solution.
08-14-2019 08:01 PM
Your SNR is high on the downstream, but the downstream has an incorrect sync rate. Upstream looks fine given the stats.
Do you have home phone service? If not, one thing you can do to make sure this problem isn't with your home wiring, is to remove the rest of your home's wiring from the equation, and then connect just your DSL modem's phone jack up to the NID / demarc. This takes a little bit of electrical load off of the line, and ensures that any dodgy wiring inside of your home is ruled out. Otherwise, if you do have phone service, check to make sure EVERY device, including alarm panels and intercoms, are behind a DSL filter. If you're having trouble filtering out some devices, Verizon may be able to help if you report DSL trouble, and install a whole-home ADSL filter inside of your NID.
If you're not sure what the NID is, it's a box or terminal found in your basement or on the side of your house (usually) where your electrical meter is. It connects the line coming from Verizon's network, to your home's wiring, and provides some surge/lighting protection too.
08-15-2019 09:29 AM
We do have phone service, and there are so many phones connected to it that it seemed impractical to buy that many DSL filters, so I used one of the filters that came with the DSL kit as a "whole house" filter. I put a jack into the line after the DSL line connects and before the ones that go to phones, and put the filter on the line that goes to all the phones. It does keep the DSL noise out of the phones, and I thought it worked fine for the DSL, but maybe it only mostly works.
That was 5 or 6 years ago, and I did buy a whole house filter at the time. Now I don't remember why I ended up not using that, and put in one of the little filters instead. What I have says "xDSL POTS Splitter" on the cover, the side says "tii communication circuit accessory model: 95S-1-12". It has a red/green twisted pair coming out of the potted part of the box, four push-in wire connectors on the inside, one of them labeled "data". There's also a jack, but that must be just for testing because the lid wouldn't close if there was anything plugged in.
Is that the kind of thing you meant, and do you think it's worth trying it? I have a very old NID, not made to hold one of these. Do you think it's worth trying it where the line splits now (maybe a foot from the NID, but inside the wall)? Assuming it doesn't outright kill it, what would I check for in the modem status report to be able to tell whether it's working better or worse? (The number of retrains is too unpredictable - this morning it had gone for three days without any, then did four of them within an hour or so).
Thanks for your help.
08-18-2019 08:36 AM - edited 08-18-2019 08:37 AM
The part "95S-1-12" would work well. Typically, the "left" side of the part will connect up to the Telephone company's demarc wiring or the NID's wiring bus. The "right" side will split off into two paris of wiring. One which is unfiltered for DSL and one which is filtered for POTS. They are self stripping parts, so no need to peel away the wiring jacket when inserting your home's wiring. Ideally, Verizon would replace your NID and install it for you when they replace the NID.
The current method you have now would work fine as well, assuming the filter itself isn't going bad (you would have noise on your phones if there was a chance of it being bad) and you don't have a bad two-way split or any loose splices/terminals. That would leave the problem with your retrains to be outside if your home wiring has been ruled out already. Again, can't stress enough before calling Verizon for trouble - if you have an alarm system, make sure it is behind a filter.
08-22-2019 02:00 PM
Ok, thanks. I installed that splitter/filter about a week ago, and so far it is doing well. It hasn't done very many retrains since then. The main change I see in the modem status data is in the CRC errors. The data I posted said it had sent 100,000+ packets each way, and had 20,000+ errors. I don't know how significant that is, but it doesn't sound good to me. When I looked just now, it had sent over a million packets each way, with no CRC errors at all. I've seen that a few times before, so it seems to be a consistent change.
For now, I'm considering the problem solved, although I've had periods before where it ran well for a week or two. Hopefully, changing the filter has done the job. Thanks for your help.
08-24-2019 03:02 PM
You're welcome. The DSL quality will certainly vary from day to day. Deep freezes or roasting hot days will typically stress the copper the most. The CRCs will cause reduced speeds and packet loss if they occurring too frequently. At this point, assuming you're all filtered up, any problem should point back to the copper sitting outside.
If you do end up getting a technician out to look at the connection, make sure they remove any bridge taps from your line. This is excess wiring that may run past your home or down side streets, that the telephone company has in place for flexibility or for future expansion. This extra wiring is supposed to be cut off from your line during DSL installation, since it can cause signal echo, and allows for more potential points of failure as the cables are weathered or serviced. This extra wiring also places extra load on the line, which reduces the maximum speed your DSL circuit can obtain without errors.