"Mark" wrote in message
...
On Wed, 2 Jul 2008 19:48:17 GMT, wrote:

Out of curiosity can anyone throw
any light on why after a short burst
of noise, your ADSL speed is significantly
reduced, and takes a long time, which can
be one or more days, to recover.
The initial reduction of profile I can
understand, speed is reduced until the
error rate makes best use of the line.
A slower connection with a stable 10% error
rate being better than a faster connection
with a 98% error rate, the latter spending
most of the time error correcting and
retransmiting errored blocks/packets.
What I can't understand is why when the
noise burst ends, and it may only last
a few seconds or less, your former
faster speed is not quickly restored,
within a few minutes rather than after
one or more days, even though thoughout
this time your modem/router is showing
a steady 15 or 16db SNR.

It can take up to 5 days to recover.

Which is precisely the point that the OP was making: it takes a long time to
recover from a brief period of noise.

A good implementation of RADSL would try frequently to see if the situation
had improved, maybe with an algorithm which lengthened the retry time if it
found that it was getting frequent bursts of noise so it didn't drive itself
silly on a permanently noisy line but recovered quickly on a line that had
transient noise.

On 3-Jul-2008, "Mortimer" wrote:

It can take up to 5 days to recover.

Which is precisely the point that the OP was making: it takes a long time
to
recover from a brief period of noise.

Exactly, I'm the original poster, and find
it takes a few days to recover from a short
burst of noise, even though my router
log shows a consistent 15.5db SNR.
I'm with Zen, and although well regarded,
they cannot fully fill the pipe, but that
is the "up to" fact of life that we
all suffer from.
What tee's me off is how long it takes
to recover.
Only solution I've found, which helps a
little is to swap Draytek and BT modems.
This seems to force two retrains, the
second when I put the original one back
again.
After a few hours, to several days later
sync rate drops again.
I suspect that BT is deliberately using
conservative settings so that connections
are slower and disadvantaged against their
own product.
My modem is next to the BT NTE5, no
extension phones or wiring, in an
electrically quiet area, quality filter,
and no SNR change when I unplug the
phone. From the router it's CAT5.

On Thu, 03 Jul 2008 11:18:03 +0000, ato_zee passed an empty day by
writing:
[snip]

The bit that has me curious is:

Only solution I've found, which helps a little is to swap Draytek and BT
modems. This seems to force two retrains, the second when I put the
original one back again.

I can only guess the system is sensing a Layer 2 MAC address change and
this forces some form of retrain ? Something is banging in my head that
makes me feel that doesn't ring right.


--
begin oefixed_in_2005.exe

"Klunk" wrote in message
...
On Thu, 03 Jul 2008 11:18:03 +0000, ato_zee passed an empty day by
writing:
[snip]

The bit that has me curious is:

Only solution I've found, which helps a little is to swap Draytek and BT
modems. This seems to force two retrains, the second when I put the
original one back again.

I can only guess the system is sensing a Layer 2 MAC address change and
this forces some form of retrain ? Something is banging in my head that
makes me feel that doesn't ring right.

Well I've certainly seen retraining when you swap routers which doesn't
happen if you simply reboot the same router - judging by the increased
length of time that the DSL light flashes and the router's status remains at
"training" before attempting to make a CHAP authentication.

"Martin²" wrote in message
news
Stupid BT has changed the way it works.
Since January my line is stuck on 12dB SNR though it worked pretty well on
6db and less before that !

Its like this:
BT sells you a car that will do 'up to' 80 mph.
In reality it will at best reach 28 mph, and the engine cuts out every few
days, if not hours.
Instead of fixing the problem, BT reduces the speed to 17 mph,
but of course it still cuts out just the same !

In real life one could get a new car or the money back,
but BT is still a monopoly and law to itself !

BT are UNNECESSARILY reducing the usability of our connection.

We now have mobile broadband, as yet it's not any better, but is meant to
improve soon. We may be giving up broadband and the BT line.....
Regards,
Martin

Amen to that!
My connection has run at an average speed of 2.5 Mb/s for the past 4 years
(albeit with a couple of disconnections/reconnections per day, which I was
happy to work around).
Two weeks ago, it suddenly dropped to an average of 1.5 Mb/s.
Since then my ISP has been trying to get BT to sort things out with no
result so far.
I'm still getting a couple of drop-outs per day but BT's way of fixing the
fault is to keep reducing my speed until hopefully no drop-outs occur. They
haven't so far admitted any fault on the line or equipment but seem to be
just tweaking my SNR - to no good effect.
Last night I was working at below 1 Mb/s.
At this rate, I'll soon be on dial-up speed.
:-(

George

"Martin" wrote in message

We now have mobile broadband, as yet it's not any better, but is meant
to improve soon. We may be giving up broadband and the BT line.....

George Weston wrote in message
Amen to that!

Enter stage left the mobile phone mast campaigners - you know the ones,
don't want masts near the school but give the kids mobile phones to take
to school and expect them to work. You know the ones who moan about slow
broadband, and then object to the mast that could give them fast wireless
broadband . . .

Where is my soap box . . .
--
begin oefixed_in_2005.exe

wrote:
Out of curiosity can anyone throw
any light on why after a short burst
of noise, your ADSL speed is significantly
reduced, and takes a long time, which can
be one or more days, to recover.
The initial reduction of profile I can
understand, speed is reduced until the
error rate makes best use of the line.
A slower connection with a stable 10% error
rate being better than a faster connection
with a 98% error rate, the latter spending
most of the time error correcting and
retransmiting errored blocks/packets.
What I can't understand is why when the
noise burst ends, and it may only last
a few seconds or less, your former
faster speed is not quickly restored,
within a few minutes rather than after
one or more days, even though thoughout
this time your modem/router is showing
a steady 15 or 16db SNR.

resynch your router. It wil come up fast and relaible.

HOWEVERE beware teh dreaded BRAS profile. BT doesn't buffer in its
DSLAMS so they will lower the BRAS rate to the lowest rate you have been
ables to sustain for a period.

That WILL take days to recover from.

In message ,
writes

On 3-Jul-2008, "Mortimer" wrote:

It can take up to 5 days to recover.

Which is precisely the point that the OP was making: it takes a long time
to
recover from a brief period of noise.

Exactly, I'm the original poster, and find
it takes a few days to recover from a short
burst of noise, even though my router
log shows a consistent 15.5db SNR.
I'm with Zen, and although well regarded,
they cannot fully fill the pipe, but that
is the "up to" fact of life that we
all suffer from.
What tee's me off is how long it takes
to recover.
Only solution I've found, which helps a
little is to swap Draytek and BT modems.
This seems to force two retrains, the
second when I put the original one back
again.
After a few hours, to several days later
sync rate drops again.
I suspect that BT is deliberately using
conservative settings so that connections
are slower and disadvantaged against their
own product.
My modem is next to the BT NTE5, no
extension phones or wiring, in an
electrically quiet area, quality filter,
and no SNR change when I unplug the
phone. From the router it's CAT5.
This thread seems to be confusing at least three issues.

1)The speed at which the OP's router is currently connected.

2)The speed at which it would reconnect if rebooted

3)The BRAS profile speed.

As I understand it

1) Once the router has connected at a particular speed it will not
change unless it looses sync or is forced to do so by one end or the
other. In that sense ADSL is not dynamically rate adaptive, but does so
in steps. Once the router has lost sync due to a noise burst and
renegotiated a lower speed at reconnection (because the line is still
noisy) its speed will not recover again until another disconnection
occurs. A reboot when the line noise improves should get the speed back
immediately (subject to 2 below). Under these circumstances the router
will resync at 6dB or thereabouts

2) On a resync ADSLMax attempts to connect the line at a target noise
level (SNR) usually 6*dB.That establishes the speed at which it
resync's. If the line has a history of frequent disconnects (more than
10 in a 1 hour period?) the BT kit will increase the target SNR in steps
to improve the lines stability. Once the SNR has been increased in this
way it apparently takes several days or weeks of stable running before
the target SNR is reduced again. (An ISP can get BT to change it
manually). Under these circumstances the OP's router would resync at 9,
12 or 15*dB each time it was rebooted.

3) BT set a BRAS speed, the maximum rate at which the ISP sends data.
This is (at least 500k?) lower than the stable rate for the link to
avoid buffering & retransmission in the BT network. This appears to
change every few hours. (daily?) depending on the stable speed of the
line.

I monitor my router using Routerstats (freeware). I am 4*km from the
exchange, all overhead wiring. During the day the SNR sits at 6 plus or
minus and the speed at 6250ish. Just before sunset it rises by 1 or 2dB
for a couple of hours. At sunset it drops down to only 1 or 2 dB and
goes back up to 6 or 7dB at sunrise. My router often looses sync at
11-12 pm when the noise level gets bad, and resyncs at 5800ish. If it
does drop out overnight, I reboot in the morning and it all goes back to
6250/6dB. A couple of days with no dropout at night and I get a 5500
BRAS. After a couple of noisy nights it drops to 5000.

As I read this post, the OP has something very like my line. Occasional
drops due to noise bursts, but is waiting for another random event or
swapping routers to trigger a resync. The question is what happens if
the OP just reboots after the noise clears. I would expect the speed to
recover.


--
Invalid

Invalid
As I read this post, the OP has something very like my line. Occasional
drops due to noise bursts, but is waiting for another random event or
swapping routers to trigger a resync. The question is what happens if the
OP just reboots after the noise clears. I would expect the speed to
recover.

It used to, rebooting when the SNR got higher then 7 brought the speed back
up to my max 2.8Mb/s.
But now it wont ! It's stuck at 12dB which gives me 1.6 - 1.7Mb/s (but
actual dwnl speed just 800kb/s).
It almost never stays up for 5 days, REGARDLESS of what the min SNR is set
to.
I am going to try swapping routers, hopefully tomorrow.
Regards,
Martin

Martin² wrote:
Invalid
As I read this post, the OP has something very like my line.
Occasional drops due to noise bursts, but is waiting for another
random event or swapping routers to trigger a resync. The question
is what happens if the OP just reboots after the noise clears. I
would expect the speed to recover.

It used to, rebooting when the SNR got higher then 7 brought the
speed back up to my max 2.8Mb/s.
But now it wont ! It's stuck at 12dB which gives me 1.6 - 1.7Mb/s (but
actual dwnl speed just 800kb/s).
It almost never stays up for 5 days, REGARDLESS of what the min SNR
is set to.
I am going to try swapping routers, hopefully tomorrow.
Regards,
Martin

I can't see where you've posted your router details but I used to use a
Netgear DG834v3 which held onto my connection come rain or shine. It would
even hold on down to 1db.

I'm now using a 2Wire 2700 which gives me a higher sync but I get more
resyncs and the occasional random reboot too.

If you're after something that will hang on to the line then I'd recommend
you try and get a Netgear. eBay has a bunch of Sky branded DG834GT
apparently going fairly cheap (can't check as eBay is filtered at work).
One of these gives you the added benenfit of being able to manuall tweak
your SNR. So even though you're currently at 12db the DMT tool or the
UberGT firmware should be able to give you something closer to 8 or maybe
less. You will need to reflash the firmware to get the Sky stuff off it but
thats a doddle.

--

WCZ