cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
2775
Views
0
Helpful
5
Replies

DMT Bits Per Bin ?

melaniemaillet
Level 1
Level 1

Hi All

I am just wondering if someone knows how to interpret the DMT Bits  Per Bin
we got in a sh dsl int atm0:

DMT Bits Per Bin
000: 0 0 0 0 0 0 0 0 2 3 3 4 5 5 6 6
010: 6 6 6  6 6 5 5 5 5 4 4 3 3 3 3 0
020: 0 0 0 0 0 0 0 0 0 0 0 B B B B B
030:  B B B B B B B B A B B A B A A A
040: 0 A A A 0 0 0 0 0 0 A A A A 0 0
050:  0 0 0 0 A 0 2 A A 0 A A A 0 0 0
060: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
070:  0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
080: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
090:  0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0A0: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0B0:  0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0C0: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0D0:  0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0E0: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0F0:  0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

I read first 6 bits where for Voice, the bits until the 31st bits  where for upstream and others where for downstream. Now I am wondering  what means the code
040: 0 A A A 0 0 0 0 0 0 A A A A 0 0
050: 0 0  0 0 A 0 2 A A 0 A A A 0 0 0

What means the zero value, is that showing bad line quality? Is someoneknows how to interpret this code?

Thanks in advance for your help

5 Replies 5

Giuseppe Larosa
Hall of Fame
Hall of Fame

Hello Melanie,

DMT uses multiple tones at different frequencies the bits per tone means if a specific tone is used or not

the tones are spaced every 4 Khz

in your case those specific lines say that some tones are not used. = 0 bits of modulation per tone

The reasons are: a safe guard is left between upstream and downstream because they travel in different directions so some tones are not used

in this range should also be included the pilot tones that are used to negotiate speed and line rate and to report other diagnostic data

this is an example taken from an ADSL1

DMT Bits Per Bin
000: 0 0 0 0 0 0 0 5 6 7 8 9 9 A A A
010: A A A A A A A 9 9 9 8 8 7 6 0 0
020: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
030: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
040: 0 0 0 0 0 4 4 4 5 5 5 5 5 2 5 5

Hope to help

Giuseppe

Hi Giuseppe,

Thanks for your help.

Got a another question if the tone is not used, will it affect the downstream quality of the line? As in a tone we can have 0 to 16bits, 0 is bad and 16 is showing good quality?

Ta

Mel

Hello Melanie,

I agree for those tones that are not intentionally not used

a 0 should be unusable for example for the presence of high interference

note that all this is dynamic: signal to noise ratios are measured for each tone over time intervals, and the modems exchange this information on some special purposes tones used for this OAM and for basic negotiation.

Hope to help

Giuseppe

Quite old post...

So I understood the higher is the tone number the higher is that bin capability, so in bandwidth terms, the higher is the sum of all bins in upstream or downstream section, the higher is the bandwidth , isn't it ??

So a pattern rich of  2, 3, 4 values is symptom of bad quality line 

Am I rigth ???

Thanks

Highly misleading reply. I know it's an old thread, but it's a high result on Google searches.

 

Melanie asked about 040-05F. Reply regarded the guard band between upstream and downstream, normally around 01E-02F (but in his DSLAM 01E-044). Of note, Melanie's line stats very clearly show the guard band being referred to, her DSLAM puts it at 01F-02A or so.

 

So let's look at what was actually reported:

DMT Bits Per Bin
000: 0 0 0 0 0 0 0 0 2 3 3 4 5 5 6 6
010: 6 6 6 6 6 5 5 5 5 4 4 3 3 3 3 0
020: 0 0 0 0 0 0 0 0 0 0 0 B B B B B
030: B B B B B B B B A B B A B A A A
040: 0 A A A 0 0 0 0 0 0 A A A A 0 0
050: 0 0 0 0 A 0 2 A A 0 A A A 0 0 0
060: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
[... all zeroes, so I'm truncating...]
0F0: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

 

THE SHORT, SHORT VERSION:

Melanie asked about 040-05F. She noted awareness of 000-007 being voice/guard.

Melanie also implied knowledge of 01F-02A being the buffer/guard between upstream and downstream.

040-05F show great bins (A, the hex for 11), and awful bins (0, and the single 2 in there) mixed in more or less at random. This implies an issue on the loop/circuit/wire.

 

Notice the very important word "implies."If you are not experiencing any issues, if you're synching at or above your purchased data rate, if you're not getting any errors/LOS/LOF/etc then odds are you're doing fine. Depending on your SLA, you may or may not be able to get a dispatch on this.

 

If you ARE experiencing issues, then this is a much stronger implication.

First step is to bounce the router or port--including reseating this cable at both ends.

If you're still having issues, you will want to re-terminate the cable (may be fastest to replace it with a known-good cable). Who knows, maybe you had a bad crimp or something.

 

If you've done all that, bounced the router, and are still having issues, let your provider know what you're seeing and what you've done. They will likely do the same thing on their end, and either check their line stats or request yours once they've done that. Once all that's done, if you're still having issues, showing errors, poor line stats... you've got a case to demand a dispatch that no provider should turn down.

 

THE LONG VERSION:

 

DMT is “Discrete Multi-Tone.” That describes how DSL works: It whistles Discrete (not discreet; it basically means distinct) Tones, a Multitude of them, onto the line at once, each tone representing a certain amount of bits of data.  

How many bits depends on the line quality.  

I'm going to add column headers (HDR, just me-speak for header) to the DMT Bits per Bin to more easily identify each bin; I'm also going to underline headers for row and column:

DMT Bits Per Bin 

HDR: 0 1 2 3 4 5 6 7 8 9 A B C D E F
000: 0 0 0 0 0 0 0 0 2 3 3 4 5 5 6 6
010: 6 6 6 6 6 5 5 5 5 4 4 3 3 3 3 0
020: 0 0 0 0 0 0 0 0 0 0 0 B B B B B
030: B B B B B B B B A B B A B A A A
040: 0 A A A 0 0 0 0 0 0 A A A A 0 0
050: 0 0 0 0 A 0 2 A A 0 A A A 0 0 0
060: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
[... all zeroes, so I'm truncating...]
0F0: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

 

So to read this, you take the row header (eg 010) and replace the last digit with the column header (eg 8). So bin 018 is the last 5 in the 010 row. Note a sensible person would have made those row headers end in an x or a * (like 0x, 01x, 02x, or 00*, 01*, 02*, etc). The engineers designing this assumed you knew what you were looking at. Typical.

 

Now notice the colour-coding I've added.

This pink colour is being used for guard bands.

This blue colour is being used for upstream.

This bold grey colour is being used for downstream.

This bright red denotes the problem area.

 

Now, each digit above represents a “Bin” or tone. There are 16 per row, the row and column headers just make it easier for you to see.  

 

The first 8 bins in 000 (technically bin 000-007) should be zeroes, they are are reserved for analog voice since DSL protocols have to (or had to) exist on the same line as voice calls.   

 

(Yup, POTS uses only 1/32nd of the tones the line is able to carry. Sad, huh?)  

All those other digits are describing a frequency and how complex of song can be whistled within that frequency, up to 16 bits.  

This is actually pretty cool physics. This is a mapping of the quality of a line for conducting each certain—ie, each Discrete—frequency. And a frequency is a Tone. And there are a Multitude of them. DMT.  

Another way to say this? You’re looking at a copper loop, but instead of your eyes receiving photons your “eyes” are the DSL interface and it is observing via voltage tones.  

Technically each of these bins has its own SNR and Attenuation. They’re like tiny 16-bit DSL lines. Cool huh?  

OK, back on track. What should you see here? Generally you should see high numbers at the lowest tones (000, 010, etc), and lower numbers the higher you go.  

Why? Because these are ever higher frequencies, and you need ever-more precise equipment and ever-more precise line quality to create and propagate a signal at these higher frequencies. Straight physics.  

(It's a little odd that the start of the Downstream carries more bits per bin than the Upstream, but that could be a quirk of the hardware in use. Or a line issue. Can't be sure.)

 

Now, look at 01F-02A. Those are all zeroes. They are a guard band, keeping the Upstream tones from bleeding over into the Downstream range and vice-versa. This is not a strict requirement via the DMT specs, but DSLAM vendors are allowed to create and use one to protect tones and transmission. Sometimes you'll just see a dip in bits per bin around here. It's all a matter of the quality of the transceivers being used there. Don't worry about this area.

 

Now, look at 02B-03F. All A's and B's, meaning in those bins (aka frequency ranges) the line can sustain whistling 10-11 distinct bits of tone on there. That's pretty excellent, really. I wouldn't be concerned here, except that all of a sudden in 040 we get 0 bits in the bin--a useless bin. And then we get 041-043 a set of A's--excellent bins. Then we suddenly and instantly drop to completely useless from 044-049, then suddenly excellent at 04A-04D, then useless again 04E-053, then excellent at 054, useless at 055. Bin 056 is NEARLY useless at 2 bits, but then immediately bin 057 is great, as is 058, 059 is useless... 05A-05C are great, and then the rest of the line is useless.

 

HDR: 0 1 2 3 4 5 6 7 8 9 A B C D E F

040: 0 A A A 0 0 0 0 0 0 A A A A 0 0
050: 0 0 0 0 A 0 2 A A 0 A A A 0 0 0

 

This is so strange that it almost seems deliberate, but I've never seen DMT bits like that. This is why in the short version I say hey... if you're not experiencing issues, then it's probably fine. But if you are, and especially if you show bad margins, errors, etc... start the troubleshooting.  

 

OTHER SAMPLE DMT BITS PER BIN:

Here are some other sample DMT Bits per Bin readouts from my job, with my header inserted for clarity:

 

Notice this one's guard band between Upstream and Downstream is quite small in comparison, and in fact may partially exist as a limitation to 4 bits on the 2 bins on either side. Notice also how it fades off from 5 per bin to 4, then 3, then 2 and finally a whole mess of bins with 1. That's far more normal.

 

DMT Bits Per Bin

HDR: 0 1 2 3 4 5 6 7 8 9 A B C D E F
000: 0 0 0 0 0 0 0 0 2 3 4 4 5 5 5 6
010: 6 6 6 6 7 7 7 7 7 7 6 6 5 5 4 4
020: 0 1 0 4 4 4 4 5 4 4 5 5 5 5 5 5
030: 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5
040: 5 4 5 5 4 5 5 4 5 4 5 4 4 5 4 4
050: 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4
060: 4 4 4 4 4 4 3 4 4 4 4 3 4 4 3 4
070: 3 4 3 4 4 3 3 4 3 4 3 3 3 4 3 3
080: 3 3 3 4 3 3 3 3 3 2 3 2 2 2 2 2
090: 2 2 2 2 2 2 2 2 2 2 2 1 2 2 2 2
0A0: 1 2 2 2 1 2 2 1 2 2 1 2 1 2 1 1
0B0: 1 2 1 2 1 1 1 2 1 1 1 1 2 1 1 1
0C0: 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
0D0: 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
0E0: 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
0F0: 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
100: 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
110: 1 1 1 1 1 1 1 1 1 1 1 1 1 0 1 1
120: 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
130: 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
140: 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
150: 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
160: 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
170: 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
180: 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0
190: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
[... all zeroes, truncated...]
1F0: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

 

Here's another one. Notice like Melanie's, this site has lower bits per bin in its Upstream of 008-01F than in its first several rows of Downstream bins. Note also the tiny guard band at 020. This DSLAM vendor doesn't need a huge blank space! We see great D and E--that's 14 and 15!--usable bits in teh downstream bins to start with, all the way down to A (10) and 9s down in 0C0-0CF.

If there's a problem here (there wasn't, this was after a repair... but IF there was), it would be in 108-116 where suddenly in this block of 3 bits per bin we intermittently can't push more than 1 bit clearly, and/or in 13E-148 where we can't push any bits, but then go back to 2 and even 3 bits per bin.

If I were trying to synch at 20Mbps downstream, this might keep me from being able to synch at that rate, or cause intermittent packet loss.

 

 

DMT Bits Per Bin

HDR: 0 1 2 3 4 5 6 7 8 9 A B C D E F

000: 0 0 0 0 0 0 0 0 3 5 6 7 7 7 7 8
010
: 7 8 7 7 7 7 7 6 6 6 6 6 6 6 5 4
020
: 0 B B C C C D D D D D D E E E E
030
: E E D E D D D D D D D C D C D C
040
: D D C C B C C C D C C D D D C C
050
: C C C C C C A 8 8 A B C B C C C
060
: B C B C B B B B C B 9 9 8 A B B
070
: B B B B B A A 6 8 A A B B B B B
080
: B B B B C B B C B B B B C B B B
090
: B C C B B C 2 B C C C C C C C C
0A0
: B C B C B B B B B B B B B B B B
0B0
: B B B B B A B A A A A 9 A A 9 A
0C0
: A 9 A 9 9 A A A A 9 8 9 9 9 9 8
0D0
: 8 8 8 8 8 8 7 7 7 7 7 7 7 6 6 6
0E0
: 6 5 5 5 5 5 5 4 4 4 4 3 3 3 3 2
0F0
: 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
100
: 3 3 2 3 3 3 4 3 1 3 1 1 3 1 3 1
110
: 1 1 3 1 0 3 1 3 3 3 3 3 3 1 3 3
120
: 3 4 4 4 3 4 2 4 4 4 4 3 3 4 4 3
130
: 3 4 3 4 3 3 3 3 2 2 2 2 2 2 0 0
140
: 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2
150
: 2 2 3 3 3 3 3 0 3 3 3 3 3 3 0 3
160
: 0 0 3 3 2 0 0 0 0 0 0 0 0 0 0 0
170
: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
[... all zeroes, truncated...]
1F0
: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

 

But again, even though we don't have that gradual trail of 3s to 2s to 1s, we still have a gradual fade vs Melanie's line's back and forth sputtering of A/0/A/0 and then 0 signal in the super high notes. If I were Melanie and were having issues, I'd be troubleshooting. If I worked at Melanie's provider, I'd be asking my tech lead why I SHOULDN'T be concerned about that area.

 

Hope this helps explain to anyone in the future!

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: