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[mikehiow]

I lost sync yesterday, at which point the phone died too. Currently awaiting an engineer.

What got me curious though was that the fttc modem is still attempting to sync jumping between initialising and establishing link. If I unplug the modem it just sits there on no signal.

I'm just curious how that's possible? What does the modem look for in the first instance before trying sync? Is it just some resistance on the line or what?



Sent from my HTC One using Tapatalk 4 Beta

[ColinS]

What does the modem look for in the first instance

Power=On?

[Black Sheep]

DSL will work to a fashion down 1-leg of the 2-wire circuit, but the PSTN (Phone) requires both legs to be intact. It sounds to me like there's an extremely high HR on either the wires or the equipment, which is allowing the router to attempt a handshake, but not providing full synch. 

[kitz]

I agree with BS,  your router is attempting the handshake, but at some point it failing one of the stages to set up the full DSL link

http://www.kitz.co.uk/adsl/adsl_technology.htm#sync

Ive watched your thread with interest because some of the things you were experiencing sounded so similar to my own problems, but BE & BS are more capable than me when it comes to FTTC technology and you are in the best of hands with them.

Like you Ive also experienced FECs with interleaving switched off...  noise bursts with no attributable source,  Ive seen changes in attenuation and although I havent experienced downstream loss of speed, I reckon I would have lost some if I didnt have a large amount of 'spare' SNRm to start with.

Its also ironic for the first time yesterday, I too started seeing issues with the physical phone line and also for the first time seeing a signs that my issue could be attributable to a HR fault.

With your phone line being down you should get some sort of priority, Im still waiting to hear when my next visit will be.   Good luck, I hope that the engineer finds where your problem is and you are soon back up and running.

[mikehiow]

What is HR? Im not convinced this is related to my broadband fault - since moving the modem back to the master socket the attenuation dropped quite a lot and my speeds have returned to normal.

Of course that's not to say my speeds weren't a mixture of two issues.

There was an OR engineer outside my house this morning pulling a new line for someone - I wonder if some work was done in the cab for that yesterday and perhaps mine was knocked.

Sent from my HTC One using Tapatalk 4 Beta

[Black Sheep]

HR = High resistance. With current flowing down a wire you want low resistance. If the wire is corroded, or trapped in a lid (thus lessening the wires cross-section -- making it thinner), then there is a higher than usual resistance impeding current flow.

The problem with your BB is related to the problem with your phone, as they both utilise the same pair of wires. We (Kitz and I) were merely pointing out how your router is attempting to synch, whilst your phone is completely dead. All this is based on what you are telling us in your own words.

[mikehiow]

I think we've crossed wires. Kitz was referring to my other thread where I was banded to 60mbps with some odd characteristics (like the FEC count with interleaving off). That's what I was responding to when suggesting my broadband issue isn't related to this incident (the phone and VDSL being down)

Thanks for clarifying what HR stands for - should have been obvious really.

Sent from my HTC One using Tapatalk 4 Beta

[NewtronStar]

Hi did you have any big thunderstorms when this happened ?

[Bald_Eagle1]

Mentioning thunderstorms, we had quite a prolonged spell of them yesterday.

Their effect can be seen in the attached 2 day montage.

Strange thing is though, how DS SNRM started to fluctuate at around 23:00 last night (quite a while after the thunderstorms had passed by) & has continued to do so since.

I forced a modem resync this morning & shortly afterward a modem reboot.
I also completely power cycled the modem on returning from work this evening.

As a consequence, my connection has now lost use of the D2 band again & DS sync speed is down to 17571 Kbps & DS SNRM still continues to fluctuate 

[ColinS]

Actually, my original post wasn't just a joke, it was observation.  The modem does not even need anything to be connected to the DSL port for it to attempt connection.  As I write this I have another DSL modem (HG622) sitting alongside me, powered up, but not connected to anything at all.  The DSL light is flashing as it 'attempts' to sync.

If you think about it, this is by design.  The modem has no way of knowing (for sure) when or whether a (temporary) line fault might resolve itself.  Is it better for it to keep trying, in the hope that sooner or later it will be sucessful, or just sit there waiting for somebody else to do something?  These things are supposed to run 24/7 unattended, so I would suggest that the former strategy is at least understandable.

[Bald_Eagle1]

Watching the HG612's GUI on a live connection, it seems to refresh the data roughly on a 10 second cycle, so that's perhaps how regularly it attempts to sync whenever anything is connected to it, even if a DSL connection is unobtainable at the time.

[mikehiow]

Sync reappeared by its self this morning. 35/13 with attainable sat just a little bit higher. Interleaving sat at 900/300.

I don't think an engineer has visited yet as the phone is still out. I just hope it doesn't take ages for the speed/interleaving to return once the fault has been fixed.

Sent from my HTC One using Tapatalk 4 Beta

[Black Sheep]

Actually, my original post wasn't just a joke, it was observation.  The modem does not even need anything to be connected to the DSL port for it to attempt connection.  As I write this I have another DSL modem (HG622) sitting alongside me, powered up, but not connected to anything at all.  The DSL light is flashing as it 'attempts' to sync.

If you think about it, this is by design.  The modem has no way of knowing (for sure) when or whether a (temporary) line fault might resolve itself.  Is it better for it to keep trying, in the hope that sooner or later it will be sucessful, or just sit there waiting for somebody else to do something?  These things are supposed to run 24/7 unattended, so I would suggest that the former strategy is at least understandable.

I have to say, this is not the case with my day-to-day findings ?? Even when I've fixed the line, the minute the synch light begins to start flashing, the EU's will generally comment that, "This is the first time it's done that for 'x' amount of days". I have my JDSU sat next to me in 'Synch & Data' mode, it remains 'Idle' until it sees a DSLAM when it will attempt to 'Handshake' and hopefully gain full synch.

Mike has posted today at 0736, that his router has connected but at extremely low speeds. This supports the evidence that there is a HR on both legs, or at least 1-leg fully 'dis' on his MPF.

[Bald_Eagle1]

Sync reappeared by its self this morning. 35/13 with attainable sat just a little bit higher. Interleaving sat at 900/300.

Are DS & US SNRM still showing plenty of scope for improvement?

SNRM on my connection has always been around the 6dB mark, confirming my connection maxes out whatever it is being sent.

However, it has lost around 10 Mbps DS since December, also seeing reduced power, particularly in the D2 band.

I don't know if lower sync speeds drive power levels i.e. a connection only uses whatever power is needed or if power levels drive sync speeds i.e. does lower power = lower sync speed (e.g. lowered power levels to combat crosstalk onto other connections)?

These lower sync speeds and power levels do also seem to coincide with the reduced speed estimates that many users are now reporting.

[roseway]

How a modem/router tries to reconnect varies from model to model, and it also depends on the router's configuration. A lot of routers have an option "Reconnect automatically". Over the years I've tested numerous different models; some of them sit there for ever trying to reconnect, even when they are disconnected from the telephone line, and others quickly give up when there's no signal. Some have to be manually prodded into action after a line disconnect. I don't think there's any "standard behaviour" for this.