chrisgilroy
join:2008-03-10
Pittston, PA
1 edit | reply to tschmidt
Re: [connectivity] Low margin and high ping issues. help please!
Well, the software obviously is the new crappy (at least imo) on the a90 but im ASSUMING that datamode is fastpath, but i definitely know on the 6100 (just checked) datamode is showing interleaved
Would the dslam be basically a "shed"? because if so im very very close to that, to my actual CO though im fairly fair away if im not mistaken.
ontop of that COULD the old (im talking very old) line coming from the pole to my house cause that much attenuation?
I actually just wikipedia'd and read that POSSIBLY the "shed" I'm referring to could be a "remote dslam" which im assuming is still somewhat "boosting" what would ordinarily be line-length that is too far to begin with? |
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tschmidt
Premium,MVM
join:2000-11-12
Milford, NH
 ·Hollis Hosting
 ·Verizon Online DSL
·Fairpoint Communic..
| Based on the attenuation numbers you are roughly 16,000 feet from the DSLAM. That could be located at the Central Office or in a Remote Terminal. DSL cannot be "boosted" like T1 or ISDN. With a remote terminal DSLAM normally located in the CO is moved nearer the customer and then fiber or copper used to backhaul data.
Just because wiring is old does not mean it is bad. As a matter of fact older wiring is often of larger gauge that has less attenuation then modern smaller wire.
/tom |
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chrisgilroy
join:2008-03-10
Pittston, PA | Hmm, I mean it is a thicker gauge wiring but I can't remember what my old numbers were because I never had these massive DC numbers. |
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chrisgilroy
join:2008-03-10
Pittston, PA | Even at 16k feet though, 3mb should work fine though no? I guess the reason I keep thinking it's something related to the connection outside of the home to the office is because as I said it worked perfectly fine at 3mb before. |
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tschmidt
Premium,MVM
join:2000-11-12
Milford, NH
·Hollis Hosting
·Verizon Online DSL
·Fairpoint Communic..
| Have you had dry loop DSL continuously? Do you remember what the margin was at 3000/768 and what it was when you first downgraded to 1500384?
Have you ever had a multi-day outage? The reason I ask is being a dry line a craftperson may have used your line for another customer not realizing it was in use. The pair you are on now may not as good as the one you were on before. Just a possibility.
/tom |
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chrisgilroy
join:2008-03-10
Pittston, PA
3 edits | I believe I did have phone service last time. I dont remember the stats when I had it back in the day though. I had about a years worth of no service (used cable) since I originally had the 3mb plan without issues.
EDIT: Sorry didn't realize what you asked. When I did (when I just had it activated a week ago), was sitting at roughly the same numbers. The really strange part, when I just had it changed to the 1500 speed my margin was like 15 for that day, (yesterday) then today its been under 7 all day. Also, since downgrading it still has lost sync about 5 times today so far.
I've only had it for about a week now, but ever since it's been losing sync, regaining sync it was typically syncing at the 3mb speed, sometimes it would dip to 2700 though. Hence the reason I decided to try 1500.
I haven't had a full days worth of outtage it typically just loses sync and resyncs within seconds. Really annoying 
I would possibly (unless it could be done without doing it at my actual pole) say that I highly doubt anyone ever touched the pairs at the pole anyway.
All I can say without a doubt, is when I originally had dsl (with phone service) it never lost sync like it does now. |
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chrisgilroy
join:2008-03-10
Pittston, PA
3 edits | Check original thread, Update2 |
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chrisgilroy
join:2008-03-10
Pittston, PA
2 edits | Check original thread, Update 3+4 |
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Jodokast96
R.I.P Bassman442
Premium
join:2005-11-23
Erial, NJ | reply to chrisgilroy
No, 16,000 ft. is pretty far for 3.0. In most cases, 13,000 is about the max. |
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tschmidt
Premium,MVM
join:2000-11-12
Milford, NH
·Hollis Hosting
·Verizon Online DSL
·Fairpoint Communic..
| As Jodokast96  posted 16,000 feet it too far for 3000/768. I don't know what the magic number Verizon uses but my attenuation is 46/31 at about 14,000 and was unable to get upgraded to 3000. When FairPoint bought northern NE from Verizon they also said I was too far but were willing to upgrade speed.
I would not be overly concerned about the differences between the two modems - the way they measure stats is a bit of an art.
That being said on a good line margin should not vary all that much. DSL is adaptive so modem and DSLAM automatically adjust speed in response to line impairments. My margin is 24/10 with 3000/768 service and varies by two or three dB. Keep in mind dB is a logarithmic measure so a 3 dB change either doubles or halves the amount of signal.
/tom
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chrisgilroy
join:2008-03-10
Pittston, PA
1 edit | Ok, left the modem sit off all day, just got home from work:
DSL Speed (Kbits/Sec) 1787 447
Margin (dB) 17.0 22.0
Line Attenuation (dB) 53.0 34.5
Transmit Power (dBm) 20.0 12.0
About 5 minutes later the down margin went to 14 and the up margin is still at 22. I notice your down margin is 24 and your up is 10 only, would it be "normal" for my up margin to be so high while the down is constantly lower always?
Also, what exactly would make it start and 17 and then just continuously go lower over the course of 10-20 minutes?
Currently sitting at about 6.4 down margin. Very frustrating.  |
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tschmidt
Premium,MVM
join:2000-11-12
Milford, NH
·Hollis Hosting
·Verizon Online DSL
·Fairpoint Communic..
| said by chrisgilroy : what exactly would make it start and 17 and then just continuously go lower over the course of 10-20 minutes? Have to ask someone else if you want to know exactly, all I have are guesses.
Since attenuation is constant the change in margin is due to noise. If attenuation were changing most likely have a circuit fault.
Customer’s upstream data arrives at CO much attenuated. Tiny DSL signal is in a cable with hundreds of other customers carrying voice, DSL, T1, BANA alarm circuits. It goes to a main distributing frame (MDF) with thousands more. That is why upstream uses lower end of the frequency band. There is less attenuation at low frequencies.
Downstream uses higher frequencies so is more affected by cable length.
Phone cable is a few feet away from power lines carrying megawatts of electricity. DSL signal is tiny compared to that. DSL signal strength is measured in milliwatts, 1/1000th of a watt. Phone cable is twisted to reduce susceptibility to noise – but nothing is perfect.
Lightning, rain, vehicles, industrial plants, radio stations (DSL overlaps AM radio) all either have the potential to inject noise into your tiny DSL signal or affect the ability of cable to reject it.
Then we have bridged taps. When phone company installs distribution cable they are not sure exactly how many pairs will be needed at each address. What this means is when a pair is used to provide phone service it may continue down the street for thousands of feet. Worse there may be more then one. At low frequencies used for voice phone service bridged taps are inconsequential, however at DSL frequencies they are a problem. Signaling protocols used by DSL can deal with bridged taps to a degree. Ideally you don't want any on your line.
Imagine you are a DSL signal originating at the Central Office traveling down the wire. For simplicity lets assume there is only one tap, at your drop. When signal get to the tap half goes to your modem the other half continues down the wire. When it gets to the end of the wire it sees an open circuit. To the signal this is like looking into a mirror. Having nowhere else to go it starts traveling back down the wire from whence it came. When it gets back to your drop and half goes to your modem the other half continues to the CO. This signal is delayed from the original due to the time it took to go down the wire and back. Think ghosts on analog TV. Won't be able to use that analogy much longer now that TV is digital. Reflected signal keeps bouncing back and forth until wire resistance dissipates energy as heat.
Bottom line instead of one nice signal traveling between CO and customer we have a menagerie of signals delayed in time running around the circuit. Sometime they add making the signal bigger sometime they subtract making it smaller.
The engineering to make century old telephone network carry multimegabit data is pretty amazing. When you think about it, it is a wonder it works at all.
/tom |
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chrisgilroy
join:2008-03-10
Pittston, PA
| You know, your one comment about having half goto the modem, the other half continue until the mirror effect. I remember when the tech (a year ago) said about my distance I was shocked. He said it was most likely due to a "loop" I BELIEVE he said, which he would have an actual linemen come out to see if they could trim that loop or something to that effect. Personally I think he didn't have any solid answers as to why I couldn't sync properly at 7mb, but I was syncing at about 4, 4.5 max (again about a year ago when I originally had DSL with phone service) so he threw that out there because me being somewhat dumb when it comes to actual DSL terminology. Ask me anything about computers and I can help/fix it, ask me about telephone/electricity and I'm lost.
So, in your opinion could my issue (attenuation AND margin) in your guess be something that COULD be fixed or do you think it's pretty much a hopeless issue that isn't worth pursuing? The only reason I ask is because unless there's a chance something may come of it, I don't want to sit on the phone with an overseas (at least the 5 people I talked to were all indian accent) tech trying to run line tests (which come back fine btw) after line test after line test.
Also, if there is this remote dslam (which I believe it is) no more than 5k feet from my house and I do happen to connect to that does that even sound remotely possible with having my trans stats?
The only reason I ask is because I'm trying to come up with some questions for the tech if I ever do get one to come out. |
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Jodokast96
R.I.P Bassman442
Premium
join:2005-11-23
Erial, NJ
·Verizon Online DSL
| If you are connected to a remote 5000ft away, your stats are way off and should show an attenuation of 20 or so on the DS. Since Tom's got 768 on the US, his margin should be lower than yours which it is, so that's kind of normal. I say kind of because, at least to me, US stats don't seem to play quite the same as DS stats. If nothing else, any tech that comes out should at least try switching your pair. |
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chrisgilroy
join:2008-03-10
Pittston, PA
| Yea, the first thing I was going to ask is if they could switch my pair, and go from there.
Again not knowing much about how dsl let alone telcom works is literally every pair in the trunk "live" to the point of where (at the pole) they could just take my pair and connect them to a non-used "live" pair or does more need to be done at the dslam/co/etc?
The only reason I ask is because if it was as simply as just switching the pair at the pole I would be (in my computer knowledge) dumbfounded as to how actual provisioning works then. Does it go by something at the co? dslam? username? (highly doubt) mac address? I would have to say something tied to the modem information only because if you could just swap lines at the pole then every line is theoretically "live" to transfer phone/dsl signal if something tries sending that particular signal.
Like Tom says, the amount of tech that goes into getting 2 copper lines to transmit actual signal and getting it to the right point just seems WOW to me. |
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tschmidt
Premium,MVM
join:2000-11-12
Milford, NH
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| said by chrisgilroy :if it was as simply as just switching the pair at the pole I would be (in my computer knowledge) dumbfounded as to how actual provisioning works then. For DSL to work it needs a copper pair back to the Central Office or RT.
Provisioning entails much more: assigning port on DSLAM, setting up ATM, setting speed, setting up user account in RADIUS server, making sure there is adequate backhaul capacity and probably lots more.
Swapping pair is much simpler. First of all probably will not be switched all the way back to the CO but to a cross connect box. High pair count cable exit the CO and get split and re split at cross connect boxes. Those are the file cabinet size green boxes you see by the side of the road. If tech finds a bad circuit section, either through manual inspection or MLT they will find an unused cable pair and use it.
If there is a bad section and there are spare pairs it is an easy task. Most likely will not affect the DSLAM or anything within the CO itself.
/tom |
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