Help With Tot Adsl

[tajartale]

I've been having a lot of problems in the past 2 weeks with my TOT 4mb package. My old Billion modem initially stopped working, so I bought a new D-Link from Pantip.

At about the same time I did this, a squirrel somehow shorted the line running into my apartment building and there was a man out on the street, fixing the line (the phone lines were all dead on that day).

Since then, I have intermittent connection with days of full speed and no problems interspersed with lots of dropping during peak hours. In the past two days, I've had virtually no internet access at all. TOT is saying I bought the wrong modem, but I'm not sure since it seems like there are other factors involved.

I have had the technician come several times. Last time he looked at the new modem I bought and said the modem was the problem and left. To his credit, his old Billion modem worked ok for the 5 minutes he was here, so he didn't check anything else. Ten minutes after he left, though, my modem worked ok too, so I wasn't sure. My modem then worked fine for 3 days at normal speed and no problems before this week.

I have noticed my SNR Margin values (down) drop from the usual 17-19 ish to around 6-8 right before I lose connection. Also, I can audibly hear A LOT of static on the phone from time to time. Also, I usually lose my connection at peak hours which would seem to be unrelated to the quality of my modem (or is it?).

I've checked that I'm setup for the correct bandwidth and on good days, I get the same speed I've been getting over the past several months. On bad days I am not getting the full speed (according to speedtest and thaivisa.com). My attenuation numbers are staying constant at around 41 down and 26 up.

I am using a brand new D-Link DSL-526B. D-Link suggested I take it back if I had a problem, but the thing is, on several days in a row, I don't have a consistent problem. So I'm not convinced the hardware on my end is to blame and anyway, replacing the old one with a new one doesn't seem to me to be something that would fix the problem, if there's a compatibility issue.

Can someone please help me sort out from this info whether my modem is, in fact, the issue or if there isn't likely something wrong outside my apartment?

Can someone also give me some suggestions for getting TOT to at least look at their line? The little machine they bring in always detects a normal speed/quality when they are here, so I'm at a loss for words at that point.

There is an office in this apartment that is usually helpful if I can give them specific information, but they aren't tech-savvy.

Any help would be greatly appreciated as I'm pretty frustrated...thanks!!!!!!

[Pib]

Just your statement of: "I have noticed my SNR Margin values (down) drop from the usual 17-19 ish to around 6-8 right before I lose connection. Also, I can audibly hear A LOT of static on the phone from time to time" indicates it's a physical line problem, either outside your residence (I.e., the TOT line & their responsibility to fix) or inside your residence (i.e., your/the building owner's responsibility to fix).

Your attenuation number is OK but with your SNR dropping down to around 6 to 8 db that is entering the area when you are probably going to loss your internet connection...it will fade in and out, etc. Go to this TV post for more specifics: http://www.thaivisa.com/forum/topic/375614-adsl-help/page__view__findpost__p__3696069 on attenuation and SNR.

I expect your modem is not the problem; just an intermittently noisy line...probably a bad/loose connection which is gets worst/gets better during the day/night due to the temperature and humidity changes....even the wind causing a swing in the telephone line or vibration from nearby traffic could affect the funky connection (i.e., gets better, gets worse). These type of connection problems can be the hardest to find.

You probably need to document specific dates and times down with the line stats (i.e., atten and SNR) and give this info to the technician when he comes again...just do your best to stress it's an "intermittent" problem and they need to check as many connection points as possible regarding your line (i.e., at the junction box, at the central station, etc). And "you" need to check as many connections as you can where the line runs "through your residence." Good luck.

[Supernova]

I have noticed my SNR Margin values (down) drop from the usual 17-19 ish to around 6-8 right before I lose connection. Also, I can audibly hear A LOT of static on the phone from time to time.

You need to make TOT aware of this. When reporting a line fault, don't mention anything about ADSL; just tell them you hear a lot of static on the phone. They will send someone out to fix it.

[lomatopo]

OK, so you had a Billion modem and everything worked fine; you never, ever had any issues. Then you bought a D-Link and have issues? If nothing else changed then the obvious culprit is the D-Link unit, or am I missing some key information?

The noise on the line usually means you have another phone jack in the circuit, so you may need some filters. You are responsible for the line in your building, not TOT.

My first instinct is that you have a problem with your in-house wiring. But you need to take a look at the D-Link's logs to see what is really going on. How often does this happen? What applications are you running?

Having said all that, I am hearing a lot of complaints about these new D-Link units, especially on TOT lines. Typically they lose connectivity to the gateway and the DNS server(s), powering the unit off/on allows reconnection.

I'd try (borrow) another modem, not D-Link. And get someone to test your internal wiring. Maybe see if there is new firmware for the D-Link (I don't think there is.)

Does anyone nearby have TOT? Do they have similar problems?

Looks like there is a lot of newer firmware out there. This box has the vaunted Broadcom chipset.

Edited November 17, 2010 by lomatopo

[tajartale]

OK, so you had a Billion modem and everything worked fine; you never, ever had any issues. Then you bought a D-Link and have issues? If nothing else changed then the obvious culprit is the D-Link unit, or am I missing some key information?

The noise on the line usually means you have another phone jack in the circuit, so you may need some filters. You are responsible for the line in your building, not TOT.

My first instinct is that you have a problem with your in-house wiring. But you need to take a look at the D-Link's logs to see what is really going on. How often does this happen? What applications are you running?

Having said all that, I am hearing a lot of complaints about these new D-Link units, especially on TOT lines. Typically they lose connectivity to the gateway and the DNS server(s), powering the unit off/on allows reconnection.

I'd try (borrow) another modem, not D-Link. And get someone to test your internal wiring. Maybe see if there is new firmware for the D-Link (I don't think there is.)

Does anyone nearby have TOT? Do they have similar problems?

Looks like there is a lot of newer firmware out there. This box has the vaunted Broadcom chipset.

Since this is the kind of response TOT will likely give me, I will respond here and try to address what was raised in the other two responses.

First of all, I do live in an older building which could be an issue. However, I have not had a serious problem with this until recently. In fact, my connection had, at last, stabilized for several months running up to this recent breakdown. Even with the old modem, I didn't have the best internet connection, back when the plans were only 2mb. Since I upgraded to 4mb, I haven't had much problem at all. I also have always noticed some fuzz on the phone, but recently it's a lot worse.

Of course, it seems suspicious to me that it started when they 'fixed' the line outside. But it probably seems suspicious to the technician that it started when I bought the new modem. So I am trying to be fair and figure out which it is.

Yes, I considered using a different modem...I would like to try a different modem! Any way to do this without having to buy a new one? The TOT guy lent me one for a week before, but last time he was here I was a little miffed and I don't think he'll do that again.

I guess I can just go out and buy one as I say, but I would like it to be one that TOT can't argue against. I did try to purchase one from TOT, but they refused to sell me anything without a new contract. Since I am likely leaving before the end of the next year, I was trying to take care of it myself.

If there's another route, I'm all ears.

Now, as for the other posters, I have more info and more questions.

Currently, I have a reasonable (but not fast) connection. It is stable enough to play radio from LA with only one or two interruptions in the past hour, but hangs a bit on all sites, including when loading thaivisa.com. The stats are as follows:

SNR Margin (dB): 17.3 19.0

Attenuation (dB): 41.0 25.0

Output Power (dBm): 19.7 11.9

Attainable Rate (Kbps): 8704 1192

Rate (Kbps): 5120 640

The low SNR Margin I was getting earlier was corrected after I reset.

My question is, can I be getting this kind of behavior while also having a problem with modem compatibility or are the two mutually exclusive? Does the low SNR Margin prove the problem isn't my modem or does it prove nothing of the kind? It would be great if I could definitely conclude one way or the other.

THanks for all your help~!

[Supernova]

The noise on the line usually means you have another phone jack in the circuit, so you may need some filters. You are responsible for the line in your building, not TOT.

Filters are used to reduce crosstalk. Static is usually caused by a fault on the line and it's TOT's responsibility to get this fixed.

[Pib]

To the OP: Most anything is possible with electronics. To further evaluate the modem side and since modem settings can make a big difference I would recommend you check some important modem "WAN" settings like:

- Mode is set to Routing

- Encapsulation is set to PPPoE

- Multiplex is set to LLC

- VPI set to 1

- VCI set to 32

- ATM QoS set to UBR

- MTU set to 1500

- Connection set to Nailed Up Connection

[Prasert]

Tajartale, you're on the right way in diagnosing the actual problem: SNR values

I checked some values on an 8M down 1M up ADSL line (G.DMT so the old ADSL v1).

The above graph shows downstream SNR in green and upstream in blue. Length of this line is about 2km untwisted copper.

(the 2 outages you see is a switched off router during lightning in the area).

The steep drops you see are completely consistent with the monsoon rains falling down at those times. However, the internet connection remains stable.

To convince TOT the problem started since they changed the wiring, you should start gathering data from your router. Either write down the SNR values manually over a longer period, or have your computer do it (the software I use is MRTG and it works by sending SNMP requests to the router, asking for SNR values. Don't know if your router supports this).

When you have more information over a longer period of time, you will most likely see a relation between the graph and the weather, and it will correspond with the static you hear on the line.

As for the change in SNR values after resetting the router (or just the adsl interface):

When the interface switches on, it starts to train the line, which means that every frequency block (called bins) is tested by the router and the DSLAM. The connection speed depends on the quality of these blocks. If enough blocks are available for the full 8M/1M connection, the DSLAM and router will negotiate this speed.

When the signal degrades over time, the DSLAM sees a decrease in SNR. If the decrease is larger than the threshold value (usually 3dB), the DSLAM will disconnect and starts training the line again.

As for the Dlink router:

I have tested numerous adsl routers over the last 3 years. The shittiest are the ones that TOT used to provide with their lines.

Turn on the logging in your router and check the messages during the time problems occur. It will probably be an addition to the list of SNR values and show that the router is not the problem.

So start collecting SNR data from your router, either manually or by a script. Multiple values measured over a period of time are very useful, contrary to one-time measurements like a speedtest.

Once you have that information, you can show the TOT employee why he doesn't see a problem at the specific moment he's checking your line. (Don't call it an engineer, as this title implies creativity and logical thinking while using your brain. Those requirements are not in their job description)

Important to keep in mind:

All of the above is only about the connection between your router and the DSLAM, and has nothing to do with internet speeds! But it is the first basic requirement for a stable internet connection.

Edited November 17, 2010 by Prasert

[tajartale]

To the OP: Most anything is possible with electronics. To further evaluate the modem side and since modem settings can make a big difference I would recommend you check some important modem "WAN" settings like:

- Mode is set to Routing

- Encapsulation is set to PPPoE

- Multiplex is set to LLC

- VPI set to 1

- VCI set to 32

- ATM QoS set to UBR

- MTU set to 1500

- Connection set to Nailed Up Connection

All the above are correct except I don't see where to set MTU or 'Nailed Up Connection'. The TOT guy ran thru the settings quickly and didn't change anything, if that means anything.

[lomatopo]

Sorry I missed the part about the squirrel and the man, my bad. What was the time-line again? Billion modem failed, new D-Link modem, no problems, squirrel, man, problems? Or Billion modem failed, new D-Link, problems, squirrel, man? If the former then have TOT check the man's handiwork, if the latter then the modem is the issue.

Can you call into your fixed line from your mobile? Can you call out from your fixed line to your mobile? If you call in to your fixed line a second time from your mobile does it ring? (Infrequently ISPs and Telcos (the same in this case) <deleted> up the voice break out and cross-connect adjacent lines causing excessive noise impacting xDSL performance.)

[tajartale]

Tajartale, you're on the right way in diagnosing the actual problem: SNR values

I checked some values on an 8M down 1M up ADSL line (G.DMT so the old ADSL v1).

The above graph shows downstream SNR in green and upstream in blue. Length of this line is about 2km untwisted copper.

(the 2 outages you see is a switched off router during lightning in the area).

The steep drops you see are completely consistent with the monsoon rains falling down at those times. However, the internet connection remains stable.

To convince TOT the problem started since they changed the wiring, you should start gathering data from your router. Either write down the SNR values manually over a longer period, or have your computer do it (the software I use is MRTG and it works by sending SNMP requests to the router, asking for SNR values. Don't know if your router supports this).

When you have more information over a longer period of time, you will most likely see a relation between the graph and the weather, and it will correspond with the static you hear on the line.

As for the change in SNR values after resetting the router (or just the adsl interface):

When the interface switches on, it starts to train the line, which means that every frequency block (called bins) is tested by the router and the DSLAM. The connection speed depends on the quality of these blocks. If enough blocks are available for the full 8M/1M connection, the DSLAM and router will negotiate this speed.

When the signal degrades over time, the DSLAM sees a decrease in SNR. If the decrease is larger than the threshold value (usually 3dB), the DSLAM will disconnect and starts training the line again.

As for the Dlink router:

I have tested numerous adsl routers over the last 3 years. The shittiest are the ones that TOT used to provide with their lines.

Turn on the logging in your router and check the messages during the time problems occur. It will probably be an addition to the list of SNR values and show that the router is not the problem.

So start collecting SNR data from your router, either manually or by a script. Multiple values measured over a period of time are very useful, contrary to one-time measurements like a speedtest.

Once you have that information, you can show the TOT employee why he doesn't see a problem at the specific moment he's checking your line. (Don't call it an engineer, as this title implies creativity and logical thinking while using your brain. Those requirements are not in their job description)

Important to keep in mind:

All of the above is only about the connection between your router and the DSLAM, and has nothing to do with internet speeds! But it is the first basic requirement for a stable internet connection.

Thanks for this thorough response. I'm trying to follow best I can! When you say "Turn on the logging in your router and check the messages during the time problems occur. It will probably be an addition to the list of SNR values and show that the router is not the problem..." can you be specific what you mean?

I turned on the log this afternoon and started checking the messages, but most of the info it reports seem to be actions ('PPP session established') and not values...it sounded to me like I was looking for numbers? Maybe I'm looking at the wrong thing. At any rate, the download speed is a little slow, but it hasn't disconnected since before I turned the log on, so there's no event to report.

My current values are like this:

SNR Margin (dB): 17.1 18.0

Attenuation (dB): 41.0 25.0

Output Power (dBm): 19.7 11.9

Attainable Rate (Kbps): 8608 1184

Rate (Kbps): 5120 640

Which seems to me to be pretty much the same as before, despite the fact that the phone is definitely more staticky now at 7pm (shhh... noise) than it was at say, 5.

I'll try to see if I can establish a pattern. Thanks again for your help.

[tajartale]

Sorry I missed the part about the squirrel and the man, my bad. What was the time-line again? Billion modem failed, new D-Link modem, no problems, squirrel, man, problems? Or Billion modem failed, new D-Link, problems, squirrel, man? If the former then have TOT check the man's handiwork, if the latter then the modem is the issue.

Can you call into your fixed line from your mobile? Can you call out from your fixed line to your mobile? If you call in to your fixed line a second time from your mobile does it ring? (Infrequently ISPs and Telcos (the same in this case) <deleted> up the voice break out and cross-connect adjacent lines causing excessive noise impacting xDSL performance.)

yeah, unfortunately the timeline is a little messed up and hard for me to pin down exactly. clearly the billion failed first. i had a substitute billion on loan from TOT for about 1 1/2 weeks. that worked fine. then one day the phone went out because of the squirrel. this was a friday. a separate TOT repairman came to work on that line (it affected the whole building). sometime over that weekend, i switched out the billion for my new d-link. there would have been a day or 2 when i was using the tot guy's billion after the squirrel incident, but i don't remember how solid the connection was for those few days. after that, i returned the loaned modem and had only my dlink to work with. it seemed to be fine at first, then got temperamental, then good for almost a week, and since then progressively worse.

hence why i wasn't in such a strong position to argue with the tot technician (even though i suspect he's incorrect).

[Prasert]

Thanks for this thorough response. I'm trying to follow best I can! When you say "Turn on the logging in your router and check the messages during the time problems occur. It will probably be an addition to the list of SNR values and show that the router is not the problem..." can you be specific what you mean?

The moment the line goes bad and disconnects, you will probably see lots of messages about the ATM circuit (=phone line connection) or PADI requests being sent. The easiest option is to copy them, post 'm here and I'll explain them.

Attainable Rate (Kbps): 8608 1184

Rate (Kbps): 5120 640

This looks like the router is capable of 8M/1M but is now connected at 5M/640k

What is the speed on your contract? Because with the current SNR values the router should be able to connect at 8M/1M (if the DSLAM offers that speed!)

And do you see any information on the modulation type? E.g. G.DMT / ADSL2 / ADSL2+

[Pib]

In my case I'm on the TOT 6Mb/512Kb plan. I have the TOT issued Billion 5210S RC modem, and a ZyXel 660R-T1 modem that JI-NET issued me when I was with them...when on JI-NET plan I was still using the TOT line/DSLAM. I switch back and forth between the two modems every few months just to ensure each one is working fine, available on a moment's notice in case one of the modems dies, to give each modem a vacation every few months, etc.

Other than getting different SNR and Attenuation readings which are about 5db different between the two modems and different setup menus, both modems work equally well on my TOT line/package. The ZyXel modem gives me about a 5db lower SNR reading and also an attenuation reading that is about 5 db lower. This 5 db difference in readings stays the same whether switching the modems out every 10 minutes or so.....or running each modem for several days to months.

Since I'm using the exact same TOT line/DSLAM when using eiether modem and the downstream attenuation should not change regardless of what modem is hanging on the end of the line, I attribute the different SNR and Attenuation different readings between the two modems to the "measurement circuits/accuracy" of each modem. Which modem is right/closer to the actual values? Impossible to tell unless a "calibrated' tester was placed on the line to make the measurements.

[lomatopo]

This looks like the router is capable of 8M/1M but is now connected at 5M/640k

What is the speed on your contract? Because with the current SNR values the router should be able to connect at 8M/1M (if the DSLAM offers that speed!)

And do you see any information on the modulation type? E.g. G.DMT / ADSL2 / ADSL2+

Incorrect. The router (modem actually) is capable of 24 Mega-bits per second. The current status of the line means that it could support a maximum of 8.608/1.184 Mbps but that it is provisioned for 5.120/0.640 Mbps.

I've had to trouble-shoot a number of lines like this, very challenging. Be patient, and good luck.

[Prasert]

TOT issued Billion 5210S RC modem

ZyXel 660R-T1 modem

Other than getting different SNR and Attenuation readings which are about 5db different between the two modems and different setup menus, both modems work equally well on my TOT line/package. The ZyXel modem gives me about a 5db lower SNR reading and also an attenuation reading that is about 5 db lower. This 5 db difference in readings stays the same whether switching the modems out every 10 minutes or so.....or running each modem for several days to months.

The values I posted earlier are measured on the DSLAM.

I compared these with a Cisco router and a Zyxel router; both the router and the DSLAM give me the same SNR value.

However, the exact value is not important.

The change in values over time is important!

[tajartale]

This looks like the router is capable of 8M/1M but is now connected at 5M/640k

What is the speed on your contract? Because with the current SNR values the router should be able to connect at 8M/1M (if the DSLAM offers that speed!)

And do you see any information on the modulation type? E.g. G.DMT / ADSL2 / ADSL2+

Incorrect. The router (modem actually) is capable of 24 Mega-bits per second. The current status of the line means that it could support a maximum of 8.608/1.184 Mbps but that it is provisioned for 5.120/0.640 Mbps.

I've had to trouble-shoot a number of lines like this, very challenging. Be patient, and good luck.

And the contract is for 4/.5...on previous contracts the numbers corresponded precisely, but ever since I switched to this contract, I've had a modem reading for 5/.64 even though I'm not supposed to and never do get those speeds. I do generally get close to the speeds I pay for. I don't know why the discrepancy. There was the same discrepancy on the previous modem and over the past 4 months.

[tajartale]

This looks like the router is capable of 8M/1M but is now connected at 5M/640k

What is the speed on your contract? Because with the current SNR values the router should be able to connect at 8M/1M (if the DSLAM offers that speed!)

And do you see any information on the modulation type? E.g. G.DMT / ADSL2 / ADSL2+

I pay for and usually get close to 4m/.5m. I don't know why, but that value has read that way since I signed the contract (though I've never gotten over 4m).

Also, I don't see where to find the modulation type. I did find this in the log and wonder if it helps answer your question:

Nov 17 17:45:17 user crit kernel: ADSL G.994 training

Nov 17 17:45:23 user crit kernel: ADSL G.992 started

Nov 17 17:45:25 user crit kernel: ADSL G.992 channel analysis

Will post again in the am or when I next can get it to drop for me.

[Pib]

TOT issued Billion 5210S RC modem

ZyXel 660R-T1 modem

Other than getting different SNR and Attenuation readings which are about 5db different between the two modems and different setup menus, both modems work equally well on my TOT line/package. The ZyXel modem gives me about a 5db lower SNR reading and also an attenuation reading that is about 5 db lower. This 5 db difference in readings stays the same whether switching the modems out every 10 minutes or so.....or running each modem for several days to months.

The values I posted earlier are measured on the DSLAM.

I compared these with a Cisco router and a Zyxel router; both the router and the DSLAM give me the same SNR value.

However, the exact value is not important.

The change in values over time is important!

Not quite sure what you mean by "measured on the DSLAM."

Are you saying the DSLAM provides the readings/values/measurement and just transmits the readings to the modem vs the modem making the measurement? If this is the case and in my case with the same DSLAM being used, the distance from the DSLAM being the same, and the routing from the DSLAM being the same to my two different modems, seems the DSLAM would send basically identical downstream readings for the two modems unless the measurement circuits/accuracy of each modem were actually making the measurement and provided different readings.

Edited November 17, 2010 by Pib

[Prasert]

user crit kernel: ADSL G.994 training - handshake procedure

user crit kernel: ADSL G.992 started - line established

user crit kernel: ADSL G.992 channel analysis

Unfortunately, the number is incomplete in your log.

G.992.1 = G.DMT

G.992.3 = ADSL2

G.992.5 = ADSL2+

Looking at the current SNR values, I assume it's G.DMT, and also since the router says it can do 8M/1M, the maximum possible with old-school ADSL (and this maybe makes lomatopo reconsider his incorrect remark).

In that case, the current SNR values are good.

And besides this discussion:

You are not paying for and entitled to 5M down and 512k up.

You may use 5M/512k of bandwidth shared with n other users. The value for n is the contention ratio.

[Pib]

Just as FYI, this link http://www.kitz.co.uk/adsl/linestats.htm has some good info explaining ADSL modem (a.k.a., ADSL router) stats/measurements. It's a little dated regarding current day ADSL upper speeds, but the basic/core info is good.

[Prasert]

Not quite sure what you mean by "measured on the DSLAM."

Exactly as it says: I query the DSLAM for specific port values.

Of course that's not allowed by subscribers, but since I work with DSLAMs on a daily base, I can check both sides.

[Pib]

Not quite sure what you mean by "measured on the DSLAM."

Exactly as it says: I query the DSLAM for specific port values.

Of course that's not allowed by subscribers, but since I work with DSLAMs on a daily base, I can check both sides.

Thanks...that explains it. Cheers.

[tajartale]

so today not having further problems, but will post here again when (probably not if) it returns. thanks for all the info!

[lomatopo]

so today not having further problems, but will post here again when (probably not if) it returns. thanks for all the info!

Did you change anything?

Like I said there are a lot of negative reports (in Thai and global forums) about these new D-Link models (all ADSL2+ compatible so 24 Mbps, which all have the same DSL chipset and firmware). I pulled some D-Link DSL-2640BT units because of complete loss of connectivity (different issue from yours I surmise),and am still trying to figure out what's wrong. Have not yet had a chance to try some of the newer firmware yet. Replacement modems are working fine.

Still curious to see your maintenance logs. Have a look through the user manual to determine how you can capture, view and save those logs.

Downloaded the User Manual, from page 69...

System Log

These windows allow you to view the System Log and configure the System Log options. To access the System Log window, click the System Log

link in the Management directory.

Click the View System Log button to view the System Log.

Click the Configure System Log button to configure the

System Log options.

Edited November 19, 2010 by lomatopo