Could someone have a look at my line stats please?

[dav333]

I have decided to start doing some research on line stats because I have always experienced lag on online games and wanted to see if I could do anything to improve it.

One thing that immediately jumps out at me from these stats is that my noise margin appears to be 0db! I noticed it was as low as 2db a a couple of weeks back but previously i'm sure it has always been between about 8db and 10db. I don't seem to be suffering from any performance drop or disconnections so I am wondering what the implications of such a low noise margin are? And what might be causing it?

Any comments/observations/thoughts on that and the rest of my stats are welcome.

Netgear DG834 v3:
--------------------------------
[DSL Modem Stats]
        US Connection Rate:     832     DS Connection Rate:     5248
        DS Line Attenuation:    35      DS Margin:              0
        US Line Attenuation:    18      US Margin:              10
        US Payload :            2979072 DS Payload:             15678336
        US Superframe Cnt :     1856520 DS Superframe Cnt:      1856520
        US Transmit Power :     0       DS Transmit Power:      0
        LOS errors:             0       SEF errors:             0
        Errored Seconds:        0       Severely Err Secs:      0
        Frame mode:             3       Max Frame mode:         0
        Trained Path:           1       US Peak Cell Rate:      1962
        Trained Mode:           3       Selected Mode:          1
        ATUC Vendor Code:       54535443        ATUC Revision:  2
        Hybrid Selected:        1       Trellis:                1
        Showtime Count:         6       DS Max Attainable Bit Rate: 5248 kbps
        BitSwap:                1       US Max Attainable Bit Rate:     n/a
        Annex:                  AnxA    psd_mask_qualifier: 0x0000
        ATUC ghsVid:  b5 00 54 53 54 43 00 00
        T1413Vid: 00 00         T1413Rev: 00            VendorRev: 00
        ATUR ghsVid:  b5 00 54 53 54 43 00 00
        T1413Vid: 00 00 T1413Rev: 00    VendorRev: 00

        [Upstream (TX) Interleave path]
        CRC:    0       FEC:    0       NCD:    0
        LCD:    0       HEC:    0

        [Downstream (RX) Interleave path]
        CRC:    6       FEC:    1638875 NCD:    0
        LCD:    0       HEC:    0

        [Upstream (TX) Fast path]
        CRC:    0       FEC:    0       NCD:    1
        LCD:    0       HEC:    0

        [Downstream (RX) Fast path]
        CRC:    0       FEC:    0       NCD:    0
        LCD:    0       HEC:    0

[ATM Stats]
        [Upstream/TX]
        Good Cell Cnt:  62064
        Idle Cell Cnt:  61868641


        [Downstream/RX)]
        Good Cell Cnt:  326632
        Idle Cell Cnt:  390313077
        Bad Hec Cell Cnt:       13
        Overflow Dropped Cell Cnt:      0

[SAR AAL5 Stats]
        Tx PDU's:       1615180
        Rx PDU's:       1171472
        Tx Total Bytes: 162369226
        Rx Total Bytes: 1116951733
        Tx Total Error Counts:  0
        Rx Total Error Counts:  1


[OAM Stats]
        Near End F5 Loop Back Count:    0
        Near End F4 Loop Back Count:    0
        Far End F5 Loop Back Count:     0
        Far End F4 Loop Back Count:     0
        SAR OAM Ping Response Drop Count=0

[roseway]

Hi and welcome.

With a rate-adaptive ADSL service (as yours is) a target noise margin is set, typically 6 dB by default. At the time of starting the connection, the router negotiates the fastest connection speed it can achieve without going below that target noise margin. After that, the noise margin will go up and down, depending on the amount of noise (interference) on the line. So in the case of your set of stats, interference has increased since the connection was established, and the noise margin has fallen as a consequence. If it falls any further the router will probably drop the connection and re-sync at a lower speed. At that point in time, the noise margin will be equal or close to the target noise margin.

All this is quite normal, but the amount by which the noise margin has fallen since the connection was established may indicate that something is not quite right with your connection. There are various things you can do to improve your own setup - see here for some hints. And to get a better idea of what is actually happening, you could install Routerstats to monitor the connection conditions over time.

[dav333]

Thanks a lot for replying.

You mentioned that if the noise margin fell any more the router will probably drop the connection and resync at a lower speed. When I checked my routers log during Sunday afternoon i noticed that the router had dropped the connection late Sunday morning and resynced at a higher speed (6464). Using Routerstats on Sunday evening showed the downstream noise margin fluctuating between 2db and 4db. On Monday morning I noticed that my router was syncing at 5600 with a downstream noise margin of 10db. A quick check in my routers log showed that my connection had dropped late Sunday evening (11pm) and resynced at 5600 shortly afterwards. From 8am Monday morning I ran Routerstats. For the first 20 minutes the downstream noise margin fluctuated between 8 and 11db before dropping to 7db, then 6db and then fluctuated between 6db and 5db. It finally settled on 5db at about 9:30am and has remained on exactly 5db ever since (over 24 hours now). Whenever I have run Routerstats the upstream noise margin & upstream/downstream sync speed graphs have always completley stable with no fluctuations.

Do you have any thoughts on the above data and its significance?

If you don't mind I also have a few general questions:

1. Whats does "rate-adaptive ADSL service" mean?
2. Apart from monitoring upstream & downstream noise margin and sync sped are there any other useful things i should be looking at in Routerstats?

[roseway]

Your noise margin seems to be bouncing around a bit, which might indicate a possible problem. If you could leave Routerstats running for several hours and post a screenshot of its noise margin graph here, it would give us a better understanding of what's happening.

1. "Rate-adaptive ADSL service" simply means a service in which the connection speed isn't fixed, but will vary depending on the line characteristics at the time the connection is made. Most ADSL services are rate adaptive nowadays.

2. Not really, but if you want to have a play with the user-defined graphs you could monitor things like CRC errors.

[jeffbb]

HI

quote : there any other useful things i should be looking at in Routerstats?

Yes you can monitor

RX totals  that is :       Mbytes totals ,SF errors ,Rs corrected Rs uncorrected

Rx CRC/ES/LOF  every 15 min or some other time scale
all directly available under the telnet tab
 see attachments
Regards Jeff

[dav333]

Thanks for the replies.
Could someone tell me how to take and post screenshots from the routerstats graphs please?

[roseway]

If you right-click on a Routerstats graph, one of the options in the popup menu is "Capture now [jpg]". This takes a snapshot of the graph and copies it as a jpg file to the directory where Routerstats is running. You can include images like this as attachments to messages you post. You'll see this option in "Additional Options & File Attachments" underneath the window where you compose the message.

[dav333]

Just one more quick question; it will work just attaching the jpg graph images from where they are on my hard drive? In other words i don't have to upload the images to an image hosting website or anything?

[roseway]

To use the file attachment method, the image just needs to be on your hard drive. When you select the image file as an attachment and post the message, the image is uploaded to the forum and stored there.  The alternative way to display an image is to upload it to an image hosting website and use [img] tags to reference its address, but for simple images like Routerstats graphs it's easier to show them as attachments.

[dav333]

I've recorded some graphs so hopefully they might help with understanding whats going on with my connection.

Graph 1 is the noise margin from Tueday evening from about 6:30-7:45pm. I had rebooted my router before starting recording the stats.
Graph 2 is sync speed over the same time period. You can see the 4 times where the router lost sync. What confuses me is that the first time the router lost sync it resynced at a higher speed.
Graphs 3 and 4 are from this morning.

Although these graphs show lots of fluctuations I have several more where there was very little fluctuation in the noise margin with the margin staying between 4db and 6db or 2db and 3db etc etc etc over a fairly long period.

[dav333]

Does anyone have any thoughts on what the graphs I posted might indicate? 

[roseway]

It looks like you have a rather noisy line, which could be a fault or it could be simply that there is a lot of interference around where you live. The fact that it sometimes drops the connection and re-syncs at a higher speed just indicates that noise levels are changing all the time - at the time the re-sync occurs the noise level is lower than it was when the connection dropped.

The first thing to check is whether you can hear any crackles or hiss on the phone. If that noise is still present when everything except the phone is disconnected (use a corded phone for this) then it looks like a line fault and should be reported as a voice fault to your phone provider (don't mention broadband). To make sure of this before reporting it, plug the phone into the test socket - see the troubleshooting guide for details.

If there is no audible noise, then the further advice in the troubleshooting guide should help to pinpoint the problem.

[dav333]

Thanks for replying. 

I have noticed the noise margin tends to drop lower later in the day although I am not sure what might be causing interference since i live in a rural area with no obvious nearby sources of interference. I don't notice any crackles/hiss on the phone.

I was going to try and plug my line into the test socket to see if that caused any improvements but unfortunately my broadband cable won't quite reach it. I'm going to buy a slightly longer cable since i don't fancy dismantling my computer, moving it, putting it back together and and then repeating the procedure. Over the past few days i have been losing sync at least 4 or 5 times late evening/overnight so it will be interesting to see what happens if i leave the router connected to the test socket overnight.

[jeffbb]

Hi
quote Graph 1 is the noise margin from Tueday evening from about 6:30-7:45pm. I had rebooted my router before starting recording the stats.

This is puzzling The SNR margin is very low ,I would have expected at least 6db or maybe something approaching 6db.

your synch speed appears to be very low ,with your attenuation of 35db you should synch at about 7520Kbps with 6db target SNR margin
can you post your bits and tone graph?

Using routerstats it might be interesting to increase the snr margin say by 6db for a couple of hours  just to see how the line would behave .

Any chance of borrowing another router ?

Regards Jeff

[dav333]

Here are some more graphs.
It seems from the graphs, that plugging into either the master socket or test socket behind the faceplate improves the sync speed and the noise margin graphs. However the noise margin graphs still look rather unstable with the test socket graph dropping from 4db to 0db and then up to 6db at one point (although it didn't resync). I left it plugged into the test socket overnight and there were no losses of sync. Early this morning whilst plugged into the test socket it was at a stable 4db with occasional dips or rises to 3db and 5db.
Does anyone have any feedback on the graphs?

I've got a few more questions if you don't mind.

1. Could somene please post some "good" or "normal" looking noise margin graphs so i can see what a good/normal/stable one is meant to look like?
2. I have never updated the firmware of my DG834 v3. Could changing the firmware affect/improve in any way the noise margin- would it be worth trying?
3. I can't borrow a router unfortunately. I was however considering the idea of getting a new router- could a different router significantly improve the noise margin and are there any that you would particularly recommend? I've read some good things about the Netgear DG834GT.
4. When switching from one telephone socket to another (as in the tests I ran) should the router by turned off first or is it acceptable to just pull out the adsl cable and plug it in the other socket with the router still on.

I haven't got enough room to post the bits & tone graphs so i'll make another post.