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 Posted: Thu Jul 03, 2008 12:48 am Post subject: Why isn't ADSL rate adaptive |
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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. |
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Eeyore
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| Posted: Thu Jul 03, 2008 1:02 am Post subject: Re: Why isn't ADSL rate adaptive |
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ato_zee@hotmail.com wrote:
| Quote: |
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.
|
Uh ?
I thought modern ADSL IS RADSL.
Graham |
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Peter Crosland
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| Posted: Thu Jul 03, 2008 1:28 am Post subject: Re: Why isn't ADSL rate adaptive |
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| Quote: |
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.
|
The simple answer is that the BT adaptive system is poorly designed, poorly
implemented and based on an ultra-conservative model. Quite simply it not
fit for the purpose it is intended for but as BT has a de facto monopoly we
are stuck with it. AIUI when BT implement ADSL2+ it should improve.
Peter Crosland |
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Eeyore
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| Posted: Thu Jul 03, 2008 3:31 am Post subject: Re: Why isn't ADSL rate adaptive |
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Peter Crosland wrote:
| Quote: |
The simple answer is that the BT adaptive system is poorly designed, poorly
implemented and based on an ultra-conservative model. Quite simply it not
fit for the purpose it is intended for but as BT has a de facto monopoly we
are stuck with it. AIUI when BT implement ADSL2+ it should improve.
|
You mean 'Max' is a poor implementatation of RADSL ?
Graham |
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Martin²
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| Posted: Thu Jul 03, 2008 7:46 am Post subject: Re: Why isn't ADSL rate adaptive |
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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 |
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Eeyore
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| Posted: Thu Jul 03, 2008 8:36 am Post subject: Re: Why isn't ADSL rate adaptive |
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"Martin²" wrote:
| Quote: |
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....
|
Who's your ISP ?
Chances are ALL the trouble lies there and I do mean 'lies'.
Graham |
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Mortimer
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| Posted: Thu Jul 03, 2008 11:05 am Post subject: Re: Why isn't ADSL rate adaptive |
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"Mark" <i@getlotsofspamthankstoplus.net> wrote in message
news:uu7p64tjj2k6aiqmdjkmdid92ct0fqg6hj@4ax.com...
| Quote: |
On Wed, 2 Jul 2008 19:48:17 GMT, ato_zee@hotmail.com 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. |
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Mark
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| Posted: Thu Jul 03, 2008 11:05 am Post subject: Re: Why isn't ADSL rate adaptive |
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On Wed, 2 Jul 2008 19:48:17 GMT, ato_zee@hotmail.com wrote:
| Quote: |
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.
--
(\__/) M.
(='.'=) Owing to the amount of spam posted via googlegroups and
(")_(") their inaction to the problem. I am blocking most articles
posted from there. If you wish your postings to be seen by
everyone you will need use a different method of posting.
See http://improve-usenet.org |
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Mark
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| Posted: Thu Jul 03, 2008 11:05 am Post subject: Re: Why isn't ADSL rate adaptive |
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On Wed, 2 Jul 2008 21:28:38 +0100, "Peter Crosland"
<g6jns@yahoo.co.uk> wrote:
| Quote: |
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.
The simple answer is that the BT adaptive system is poorly designed, poorly
implemented and based on an ultra-conservative model. Quite simply it not
fit for the purpose it is intended for but as BT has a de facto monopoly we
are stuck with it. AIUI when BT implement ADSL2+ it should improve.
|
I think the conservatism might be down to ISPs (by which I mean BT
Retail) needing something as stable as possible for services like BT
Vision that need a decent level of network QoS.
If you know a line has found its long-term average level, as an ISP
trying to deliver services critically dependent on stability that's
precisely what you want.
I imagine a line flapping around with its sync trying to support IPTV.
I'm not saying it's right or wrong, I'm merely suggesting why it's
been done that way. |
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Mark
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| Posted: Thu Jul 03, 2008 11:05 am Post subject: Re: Why isn't ADSL rate adaptive |
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On 03 Jul 2008 06:43:23 GMT, Klunk <bill.gates@microsoft.com> wrote:
| Quote: |
On Wed, 02 Jul 2008 21:02:06 +0100, Eeyore passed an empty day by writing:
ato_zee@hotmail.com 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.
Uh ?
I thought modern ADSL IS RADSL.
Graham
AFAIR Graham you are spot on. The 'fixed' speeds we once had
(512/1024/2048) were capped in software. ADSL 'Max' or RADSL removed
these fixed settings and let the hardware make the decisions.
|
Oh that it were so. BT Wholesale's network manager for ADSL Max
actually makes the decisions.
| Quote: |
Any DSL that has the ability to change speed due to line conditions is,
by nature, rate adaptive.
|
Subject to the above. |
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Klunk
Guest
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| Posted: Thu Jul 03, 2008 11:05 am Post subject: Re: Why isn't ADSL rate adaptive |
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On Wed, 02 Jul 2008 21:02:06 +0100, Eeyore passed an empty day by writing:
| Quote: |
ato_zee@hotmail.com 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.
Uh ?
I thought modern ADSL IS RADSL.
Graham
|
AFAIR Graham you are spot on. The 'fixed' speeds we once had
(512/1024/2048) were capped in software. ADSL 'Max' or RADSL removed
these fixed settings and let the hardware make the decisions.
Any DSL that has the ability to change speed due to line conditions is,
by nature, rate adaptive.
--
begin oefixed_in_2005.exe |
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Guest
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| Posted: Thu Jul 03, 2008 4:18 pm Post subject: Re: Why isn't ADSL rate adaptive |
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On 3-Jul-2008, "Mortimer" <me@privacy.net> wrote:
| Quote: |
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. |
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Klunk
Guest
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| Posted: Thu Jul 03, 2008 5:02 pm Post subject: Re: Why isn't ADSL rate adaptive |
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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:
| Quote: |
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 |
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Mortimer
Guest
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| Posted: Thu Jul 03, 2008 5:12 pm Post subject: Re: Why isn't ADSL rate adaptive |
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"Klunk" <bill.gates@microsoft.com> wrote in message
news:486cbfb8$0$2912$fa0fcedb@news.zen.co.uk...
| Quote: |
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. |
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George Weston
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| Posted: Thu Jul 03, 2008 10:21 pm Post subject: Re: Why isn't ADSL rate adaptive |
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"Martin²" <never@give.one> wrote in message
news:DeGdnfyzW9wToPHVnZ2dnUVZ8qTinZ2d@posted.plusnet...
| Quote: |
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 |
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