DSL Status - What Does It All Mean?

[willscott]

I have 2 accounts with Plus; one at home, and one on my air cadet squadron. Both use the same Linksys hardware.
Whilst trying to trouble shoot why my home connection has stopped working since I was upgraded to IPStream Max, I came across the DSL Status page in the WAG354G.
Can anyone shed any light on what these pages are telling me, especially the Downstream/Upstream Line Attenuation, which are different by a magnitude of 2. The first is my squadron, the second my home

[Cliff_Jordan]

In simple terms (the only ones I understand) the line attenuation figures relate to how noisy the line is. The higher the figure, the more noisy the line and the slower the sync speed will be. The difference between upstream and downstream is because the sync speeds are different. No doubt someone else will be along to give a more technical explanation of this - or correct mine.
But there does seem to be a problem with both connections when I compare them with mine, as I am getting a much higher download speed with a higher attenuation figure.

[Anotherone]

Here is a more correct explanation -
Attenuation is a function of line length.
Downstream (DS) Attenuation is always greater than Upstream because DS runs at a higher frequency and gets attenuated more (physical fact).
Interleaving is a form of providing error correction, when off (ie Fast) it will give you slightly more speed but more prone to errors and possible disconnects with a bad line. Also when off, you get less latency.
Your home connection seems to put you closer to your exchange than your squadron is to theirs. You should be able to achieve a much better connection at home.
Were those figures obtained from the SAME router, or 2 routers?
I am baffled by the fact that your home router is showing DSL status "Up" but no DS or US rates!
Edit: With your line attenuation you should be able to achieve maximum speed if your line is not noisy. You are about 2Km from your exchange.
Whiffler is about 2.5Km from his exchange, based on the attenuation figure and should be able to get higher sync speeds around 7M, but his noise target may have gone to 12dB as the SNR Margin is showing 12dB, this will reduce the sync speed. He may have a noisier line.

[zubel]

From Wikipedia:

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Attenuation is the reduction in amplitude and intensity of a signal. Signals may attenuate exponentially by transmission through a medium, or by increments calculated in electronic circuitry or set by variable controls. Attenuation is an important property in telecommunications and ultrasound applications because of its importance in determining signal strength as a function of distance. Attenuation is usually measured in units of decibels per unit length of medium (dB/cm, dB/km, etc) and is represented by the attenuation coefficient of the medium in question.

Basically, we know the attenuation coefficient of a copper wire so from the calculated attenuation we can generally determine the *length* of the wire.
This is the first and foremost limiting factor with ADSL speed.  As your line length increases, your attenuation increases and the amount of 'signal' that can be squeezed down it reduces.
The difference between the two images you posted indicate to me that the line with the higher attenuation is simply a longer physical line from the exchange and so should not be anything to worry about.
B.

[Anotherone]

Education is a wonderful thing B ;)
And this forum or my connection seem a bit laggy at the moment ::)

[willscott]

I actually invested in a Philips modem/router over the weekend to see if the 2 Linksys devices I had tried were at fault. The philips actually showed that 8Mb can be achieved.

[Bob_Milton]

Here is a definition of dBs and an indication of their significance.
I offer it because of your remark mentioning a differing magnitude of 2.
dB, deciBel, 1/10th of a Bel. It is a logarithmic expression of a power ratio, used so that gains and losses may be added or subtracted to or from a signal, instead of multiplying and dividing. The Bel is a large unit hence the use of deciBels.

Example: if the power ratio is 2:1 or 1:2 then the difference is said to be 3dB (approx). Log2 is .3010, so ten times log2 is 3.01dB.
I'm sorry if the definition confuses instead of helping.

[Anotherone]

The Philips modem router seems to show you happily syncing at 8128! and confirms your line attenuation.

[zubel]

Which leads me to believe that the upgrade to MAX isn't causing the problem.
I suspect that BT may have done something incorrectly at the exchange.  So you're syncing happily with the exchange, but the communication between the exchange and Plusnet is at fault.
Moving back to a fixed 2Mbps product *may* solve the problem but I would hazard a guess that it may still persist.
I would stick with the MAX product in all honesty.  Once the authentication is fixed, you'll be up and running on a top-speed product.
Have you been asked to try the bt_test_user@plusdsl.net and/or bt_test@startup_domain usernames in your router?
Alternatively, is there a log in your router anywhere that may show Authentication problems? (It will say cryptic things along the lines of CHAP Authentication and possibly LCP/PPP comments).  If so, could you post the log?
B.

[willscott]

Quote from: Barry

Have you been asked to try the bt_test_user@plusdsl.net and/or bt_test@startup_domain usernames in your router? Alternatively, is there a log in your router anywhere that may show Authentication problems? (It will say cryptic things along the lines of CHAP Authentication and possibly LCP/PPP comments).  If so, could you post the log? B.

Yes, I've tried those test accounts daily, with no success.
From memory my router doesn't have a log detailing authentication problems. I'll look tonight though.
Your suggestion that the exchange isn't communicating with PN sounds plausible, as that would explain why my account works on another line, but not at home. Can anyone from Plus.Net check this out?

[#11]

I wonder if its been provisioned on the incorrect realm. Perhaps something went pear shaped when they did the upgrade.
Guess only PN would be able to check/order investigation though.

[Chris]

Quote

I wonder if its been provisioned on the incorrect realm.

Already been checked, nothing wrong there.

Quote

bt_test@startup_domain

That username doesn't even hit our network and should work for *any* customer using an IPStream product. When logged in to this you'll only be able to browse to one page, www.bt.net/digitaldemo IIRC.
I've got an idea, PM on the way willscott.
In fact, it won't work :( If you can't log in to the @startup_domain test login then giving you a different account to log in on won't work.

[James]

Good call James, that was exactly what I thought initially, but that wasn't the case.
Even if it had been, he would have been able to log into bt_test@startup_domain which he wasn't able to do so.
It looks like BT botched something as part of the upgrade, of which we (me and Christopher) are hopeful will be rectified as part of the downgrade.

[Anotherone]

I agree Barry, 2 threads are confusing, but this one originally was about how to interpret the stats. The other was about his connection problem and the one PN were addressing (or not as the case may be!!).
@James,
Why not just tell BT to get their collective finger out. The problem is clearly with them!!

[paulby]

Barry locked the other thread as I was posting!  So, in reply to this:

Quote

Paul, I have access to another PN account in another location. I reconfigured the modem to connect using my home account details, and it connected no problem, and used my static IP address, so I conclude that there isn't a problem with my username/password.

It could be, as Jameseh has said (in the other thread) that you may have been reprovisioned on the wrong realm (the bit after the @ in your user name).
If this is the case then you won't be able to log in on your line but would explain why you could log in at the other location.
I think it would be worth PMing Jameseh or phoning support to find out what they think your user name is (particularly the bit after the @) and, if it hasn't changed, what realm your line has been assigned.
Edit: Scrub that - just noticed Jamesh has posted while I was typing!