3BB Fiber problem

[phukettrader]

Question for all you telecoms experts out there..

For the last three days, I have woken up to find that my 3BB FTTx connection is down. The red LOS light on the 3BB supplied FibreHome router is blinking and the PON light is off. Power cycling the router does not solve the problem. However, at about 09:00-09:30 the link returns to normal all by itself.

The first couple of days I thought that maybe 3BB were playing, but after it happened again last night, we called 3BB to report a problem. Their answer was that no, they have not been playing, and the problem is me because I should turn the router off every night because maybe it gets too hot!! Even after explaining that it has been working perfectly for over a year now and the only time the router normally gets reset is when we have a power cut, they would not change their position and have refused to send a technician to take a look.

Here's some background, I live in rural Chiangmai and for the last three nights, coinciding with this problem, it has been rather cold with temperatures going down to about 19 degrees overnight. Looking at the logs on my CISCO RV320 router (I use the 3BB kit in Bridge mode together with a backup ADSL connection and both feed into the CISCO Dual WAN router which does the "real" work), I can see that every night, the fibre connection drops at between 01:00 and 02:00.

I was therefore wondering whether it is possible that there is a dodgy connection somewhere, maybe in the main junction box in the road outside my house, such that the cables contract and expand with the heat, with the connection being broken when the temperature falls below a certain level. Is this possible with the fibre technology used here?

Over to you experts, as I would like to go back to 3BB with a credible scenario if it happens again tonight.

Any ideas?

[Gregory Morozov]

With that regular pattern I highly doubt the cable is the problem. Much more likely some hardware on the way loses power and gets powered back on again in the morning, maybe manually when someone comes to work at 9...

[Pib]

Yea, sounds like a 3BB problem. And their response about you should turn your router off every night because it gets hot is laughable. Heck, at night the router would be running cooler than day time due to lower ambient temperature at night. Call'em back...get a tech to your home...make the problem sound worst if necessary. Got to go....I have some more laughing to do...3BB customer support should go into the comedian business.

[keeniau96]

In the past month or so I have had several occasions with the 3BB fiber service, exactly as described by the OP. Last time was about a week ago, started around mid-day and continued into late evening and night. Called 3BB who have been very helpful on several previous occasions. Wife talked to them who explained that it was happening because of 3BB equipment additions and just wait a bit. Waited until late evening, went to sleep, in the morning green light and back to normal.

[phukettrader]

Well, it happened again last night - off at about 22:30, back on at about 08:30. Called 3BB again and explained that we are fairly sure the problem is due to something going on with their equipment somewhere between my house and their main "hub". They are now going to send somebody to have a look at my house - not sure what because everything is working again!

The girl on the helpdesk also kindly suggested that they can't find the problem I should probably cancel the service - laughable

[Cheesekraft]

I am having the same problem with sinet ad well in Chiang Mai

[phukettrader]

OK, so two guys from 3BB have just come and they said the problem was that the fiber transmit power was wrong. it was -30.45DB and they said it should be about -27DB (whatever that means!). They spliced a thinner yellow fibre optic cable onto the existing black fibre cable in the back of the router, then fiddled around with the main junction box in the road outside for about 1 hour, after which the router reported transmit power of -22.55DB, which they said that was OK and left.

So, we will see what happens tonight...

[RichCor]

The numbers they're stating deal with the power level of the light travelling to your Fiber Optic port.

Most FTTx installations are 'shared' services, even if you may currently be the only 'customer' currently on that individual fiber optic trunk line, it has the capacity to serve 32 or 64 'customers' before reaching/exhausting capacity of that fiber optic run.

The originating light 'signal' has to be powerful enough to reach all of the connected customers, and survive going though various optical splitters and splices along the way. Apparently 3BB believes it is delivering too bright a signal to your port connector. Your Fiber Optic modem has a range of light 'brightness' or 'sensitivity' range it can reliably operate in. Some optical modules have an operating range of -29 to -8 dBm.

A decibel (dB) is a unit used to express relative differences in signal strength (power or amplitude) using base 10 logarithm rules.

dBm is decibel in milliwatts. These units are used to quickly assess gain or loss (without having to invoke complex mathematics).

My TOT FTTx connection is delivering -28 (dBm) Optical module input power. Since FTTh is a 'shared service', if other new customers are inserted on the same fiber optic line prior to my splitter then this value will drop (attenuate) towards 0 by 0.3dB for each customer inserted prior to me.

I'll shut up now.

[phukettrader]

Thank you RichCor for that detailed explanation of the fibre optic technology. I can't say that I understand everything you said, but it does at least put what 3BB were saying into some context.

I still can't get my head around why this has only just started happening for the last 4 nights after working perfectly for nearly one year, nor why the problem only happens in the night time. During the day it never drops the connection.

I still prefer the idea proposed by Gregory in the first reply that some breaker is tripping somewhere upstream from me and Somchai is resetting it every morning when he pitches up for work without reporting the problem up the command chain, but I guess we'll wait and see if it drops again tonight...

[Pib]

Acceptable downstream (receiving) and upstream (transmitting) power levels are critical for proper fiber and DOCSIS (cable) internet speed and reliability. Just for example a person might think that the more power the better for the downstream/receiving leg but actually too much power can be just as bad as not enough power.

I remember when still living in the U.S. I had a DOCSIS/cable plan also and it stopped working one day. The cable guy came out and found a power splitter had failed...failed in a way to greatly reduce the downstream/receiving power. He said for their system that a -7dbm was perfect.

But it varies from system to system as to what are acceptable power level. Just for example and "Generally", repeat "generally' for DOCSIS (cable) internet the levels shown at this weblink are what your are looking for. And my TrueOnline DOCSIS plan is within the limits, although approaching the higher end of each limit especially for the modem transmitting/upstream power...been that way for years...and I am at the end of their trunk line in my moobaan....but I will have to say (knock on wood) my TrueOnline reliability/up-time has been like 99.9%. Even during the big flood of late 2011 when I had over a meter deep water in my moobaan for almost a month my True Cable TV and Internet never went down. Folks on TOT ADSL, the other internet provider to our moobaan, lost their internet day one of the flooding due to the ground level junction boxes being under water....but for the True cable TV and internet all their cabling and electronics are high on the poles.

Don't have a clue what the acceptable power levels are for a "fiber" system.

At this moment in time at 8:55pm here in Bangkok below is what my cable modem shows for downstream and upstream power levels.

[phukettrader]

Well, looks like whatever the 3BB boys did yesterday did the trick. Signal did stayed up all night without a hiccup

[55Jay]

An interesting thread!

[RichCor]

Made a bit of a mistake on my dB / dBm levels explanation.

Since dBm here is a measure of 'Gain' or 'Loss', with '0' as reference signal level, then -n (negative values) are used to represent fractional loss.

-3dBm represent a ~0.5 or 1/2 of original signal being received. Each 3dB movement represent a Gain of 100% (x2), or a Loss of 50% (1/2) power.

-6dBm represents ~0.250 or 1/4 of original signal being received.

-9dBm represents ~0.125 or 1/8 of original signal being received.

-10dBm represent ~0.1 or 1/10 of original signal being received.

So when 3BB said they measured -30.45dBm (decibel milliwatt) that is equal to 0.0009015 (~1/1000) of original reference signal.

When they made the adjustment to -22.55dBm, that is equal to 0.005559 ( ~1/180) of original reference signal being received, so big difference.

Gotta love logarithmic scales.

The original signal level was much too low, outside of the low-end range of the Router's Optical Sensor specifications.

If it was a Fiber Optic cable issue then is would have affected light signal levels in both UL and DL directions.

So it sounds reasonable that 3BB identified the correct issue and resolved it for you.

[wgdanson]

On 11/24/2015 at 11:06 AM, phukettrader said:

Power cycling the router

Do you mean turning it off then on again?