There was a major outage last week in BT's ATM network that caused I, and
others, to lose ADSL connectivity..

...The support I got when I reported it is not good, but in following up the
issues to do with the (lack of) support this website came up.

http://www.metronet.co.uk/adsl/exchangeChecker

Basically, it allows you (or someone else, if you are current;ly ****ed) to
check to see if there is a fault within BT's major ATM backbone that
affects one or more exchanges.

Out of interest, I also discovered that my router (D-link D504, older than
Methuselah) had ADSL diagnistics (which passed, showing I could talk to the
DSLAM at the local exchange) and indeed ATM diagnostics, which showed that
that was as far as I could get.

(Essentially ADSL is what you use to talk to the exhange - like a super
modem - ATM is the next protocol level which BT uses to pass your signal
off to the ISP, and the PPP layer protocol is what you use to talk over
that to your ISP, log in, and start up IP services over the rest)

In this case the ATM link was clearly broken...

I pass this on as potentially useful info to people who have broadband
problems...at least you can 'phone a friend' and get them to use this to
see if YOU are currently suffering a known outage, or whether as the
helpful BT man suggested ' you router,she is obviously broken'

:-)

It also allows you to see if your exchange is subject to a high contention
ratio, and is therefore slower than it should be.

Enjoy, you sad nerds like me :-)

"The Natural Philosopher" wrote in message
...
There was a major outage last week in BT's ATM network that caused me, and
others, to lose ADSL connectivity..

..The support I got when I reported it is not good, but in following up
the
issues to do with the (lack of) support this website came up.

http://www.metronet.co.uk/adsl/exchangeChecker

Basically, it allows you (or someone else, if you are current;ly ****ed)
to
check to see if there is a fault within BT's major ATM backbone that
affects one or more exchanges.

Out of interest, I also discovered that my router (D-link D504, older than
Methuselah) had ADSL diagnostics (which passed, showing I could talk to
the
DSLAM at the local exchange) and indeed ATM diagnostics, which showed that
that was as far as I could get.

(Essentially ADSL is what you use to talk to the exhange - like a super
modem - ATM is the next protocol level which BT uses to pass your signal
off to the ISP, and the PPP layer protocol is what you use to talk over
that to your ISP, log in, and start up IP services over the rest)

In this case the ATM link was clearly broken...

I pass this on as potentially useful info to people who have broadband
problems... at least you can 'phone a friend' and get them to use this to
see if YOU are currently suffering a known outage, or whether, as the
helpful BT man suggested, 'your router, she is obviously broken'.

:-)

It also allows you to see if your exchange is subject to a high contention
ratio, and is therefore slower than it should be.

Enjoy, you sad nerds like me :-)


Brilliant info for u nerds on BT. Is there an equivalent diagnostic thingy
for ntl cabled broadband which is known as DSL?
Jim

Jim Gregory wrote:
Brilliant info for u nerds on BT. Is there an equivalent diagnostic thingy
for ntl cabled broadband which is known as DSL?

Cable broadband is not DSL. ADSL is DSL.

Alex.

"Alex" wrote in message
...
Jim Gregory wrote:
Brilliant info for u nerds on BT. Is there an equivalent diagnostic
thingy for ntl cabled broadband which is known as DSL?

Cable broadband is not DSL. ADSL is DSL.

Alex.

Oops, I had thought it was!
Jim

On Wed, 25 Jan 2006 18:18:28 +0000, Alex wrote:

Jim Gregory wrote:
Brilliant info for u nerds on BT. Is there an equivalent diagnostic thingy
for ntl cabled broadband which is known as DSL?

Cable broadband is not DSL. ADSL is DSL.

Alex.


Neither of them are broadband, but that's another story.


--

..andy

Andy Hall wrote:

On Wed, 25 Jan 2006 18:18:28 +0000, Alex wrote:


Jim Gregory wrote:

Brilliant info for u nerds on BT. Is there an equivalent diagnostic thingy
for ntl cabled broadband which is known as DSL?

Cable broadband is not DSL. ADSL is DSL.

Alex.



Neither of them are broadband, but that's another story.

Agreed!

Quite why the term 'broad band' came into use in computers, I have no idea.

The use of two wires to connect to the internet is called a serial
connection. As such, it can never be specced as broad band. Broad band
is the ability of a signal to occupy a wider spectrum. As such, only a
modulated signal can be broad band. i.e. the data is not in a serial
stream, but is spread across a wide frequency.

What is called broad band, these days, is just a very fast serial
connection.

To clarify this...

Broadcast FM transmissions use a broad band system. About 25 KiloHertz.
Don't quote me, it is late at night and the whisky bottle is low in content.

Medium wave transmissions uses a narrower band.

Morse code is a true narrow band system, signal on, signal off, just
like the way we connect to the internet.

HTH

Dave

In
To clarify this...

Broadcast FM transmissions use a broad band system. About 25 KiloHertz.

200 kHz ;-))
Don't quote me, it is late at night and the whisky bottle is low in content.


|Thats OK)
Medium wave transmissions uses a narrower band.


9 kHz
Morse code is a true narrow band system, signal on, signal off, just
like the way we connect to the internet.


Lo lo hz
HTH

Dave

--
Tony Sayer

In article ,
says...
Andy Hall wrote:

On Wed, 25 Jan 2006 18:18:28 +0000, Alex wrote:


Jim Gregory wrote:

Brilliant info for u nerds on BT. Is there an equivalent diagnostic thingy
for ntl cabled broadband which is known as DSL?

Cable broadband is not DSL. ADSL is DSL.

Alex.



Neither of them are broadband, but that's another story.

Agreed!

Quite why the term 'broad band' came into use in computers, I have no idea.

The use of two wires to connect to the internet is called a serial
connection. As such, it can never be specced as broad band. Broad band
is the ability of a signal to occupy a wider spectrum. As such, only a
modulated signal can be broad band. i.e. the data is not in a serial
stream, but is spread across a wide frequency.

What is called broad band, these days, is just a very fast serial
connection.

To clarify this...

Broadcast FM transmissions use a broad band system. About 25 KiloHertz.
Don't quote me, it is late at night and the whisky bottle is low in content.

Medium wave transmissions uses a narrower band.

Morse code is a true narrow band system, signal on, signal off, just
like the way we connect to the internet.

HTH

Dave


My memory of these things is very rusty, as I haven't worked in the area
for some time, but isn't ADSL transmitted (on the local loop at least)
using DMT (Discrete Multi-Tone)? From what I remember, it uses many
channels, spread over the 1MHz or so of bandwidth on a local pair
(effectively Frequency Division Multiplexing). If correct, is this not
broadband as you defined it above?

I agree once it gets into the DSLAM, it is converted to true serial bits
on the STM-1 (4? / 16?) link into the ATM network. Even serial data uses
bandwidth though, proportional to the rate of change of bits, or
something like that!

Probably all changed significantly in the last 5 years though!

Dave wrote:

Neither of them are broadband, but that's another story.


Agreed!

I expect you are agreeing at crossed purposes! ;-)

The use of two wires to connect to the internet is called a serial

Erm... huh?

The connection between my TV and its aerial is with two wires... does
that make it serial also?

connection. As such, it can never be specced as broad band. Broad band
is the ability of a signal to occupy a wider spectrum. As such, only a
modulated signal can be broad band. i.e. the data is not in a serial
stream, but is spread across a wide frequency.

Which is exactly what ADSL does - transmits a modulated waveform down a
copper pair with a wide bandwidth (relatively at least compared to the
normal voice channel bandwidth of 3.4kHz).

What is called broad band, these days, is just a very fast serial
connection.

depends on what level you look at it... you could argue that ethernet is
a serial link with differential manchester encoded signalling on the
wire - but it is not what most people would call a serial link.

To clarify this...

Broadcast FM transmissions use a broad band system. About 25 KiloHertz.
Don't quote me, it is late at night and the whisky bottle is low in
content.

ADSL uses just under 1MHz of bandwidth on the downlink side. The
modulation scheme used is form of Orthogonal frequency-division
multiplexing (OFDM) although many DSL modems routers refer to it as
discrete multitone modulation due to the way the bandwidth is broken up
into a multiple of parallel tone bands to overcome any dropout frequency
regions in your phone line's response.

(the ADSL signal also starts at over 25kHz - way above the audio signal
on the phone line)

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Wed, 25 Jan 2006 23:05:35 +0000 (UTC), Dave
wrote:

Andy Hall wrote:



Cable broadband is not DSL. ADSL is DSL.

Alex.



Neither of them are broadband, but that's another story.

Agreed!

Quite why the term 'broad band' came into use in computers, I have no idea.


I can give an insight here..

When I first got into data networking in the early 80s, ethernet was
pretty new and IP was just coming into being through the works of Vint
Cerf and Jon Postel among others; the term 'broadband' was used to
describe multiservice networks based around bandwidth division of
cable TV infrastructure.

In fact there were systems for delivering 10Mbit ethernet presentation
using three channels of such a system provided that it was engineered
correctly. There were data networks using this and more channels to
obtain what were, for the time, quite high bandwidths over areas much
in excess of what could be done using ethernet with repeaters.

Thus broadband came to mean an infrastructure over which one could
deliver data, voice and broadcast quality TV services.

More recently, the notion of being able to deliver data/voice/video
over phone lines to the home had great appeal to the marketeers at the
telcos. So much so, that they thought that calling this 'broadband'
would be a great way to describe it. They even believed their own
bull**** to the extent of trying to sell it in this way full of the
promises of multimedia.

The reality has fallen far short of that. None of them ever
described their services as slow. The 110 and 300 baud modems of
the 70s gave way to 1200, 2400 and so on up - each having "blazing"
speeds. At one point, even 128k ISDN was described as "broadband".
Even in comparison with 56k modems that's a stretch.

To describe standard ADSL as "broadband" is a downright lie. The
higher speeds are only available very close to the exchange. 512k and
1Mb services are much more typical for most users.

Broadcast quality TV (meaning full size screen on a TV set) isn't
possible at these bandwidths (at least with today's codecs)
The 256k return bandwidth makes the service unusable for any form of
quality video conferencing other than fairly crude desktop stuff.

So not only are these incompetent telco marketeers not delivering a
broadband service, they are not even delivering on what they tried to
convince us that the technology could do.

Arguably, the closest technologies to broadband are cable modem and
satellite. Both can deliver data services, but neither are very good
at it. At least they can deliver broadcast quality TV.



--

..andy

Jim Gregory wrote:

Brilliant info for u nerds on BT. Is there an equivalent diagnostic thingy
for ntl cabled broadband which is known as DSL?

Ignoring your terminology,
http://homepage.ntlworld.com/robin.d.h.walker/cmtips/ is a good
starting-point for all things cable modem.

Douglas de Lacey

"Jim Gregory" wrote in message
...
"The Natural Philosopher" wrote in message
...
There was a major outage last week in BT's ATM network that caused me,
and
others, to lose ADSL connectivity..

..The support I got when I reported it is not good, but in following up
the
issues to do with the (lack of) support this website came up.

http://www.metronet.co.uk/adsl/exchangeChecker

Basically, it allows you (or someone else, if you are current;ly ****ed)
to
check to see if there is a fault within BT's major ATM backbone that
affects one or more exchanges.

Out of interest, I also discovered that my router (D-link D504, older
than
Methuselah) had ADSL diagnostics (which passed, showing I could talk to
the
DSLAM at the local exchange) and indeed ATM diagnostics, which showed
that
that was as far as I could get.

(Essentially ADSL is what you use to talk to the exhange - like a super
modem - ATM is the next protocol level which BT uses to pass your signal
off to the ISP, and the PPP layer protocol is what you use to talk over
that to your ISP, log in, and start up IP services over the rest)

In this case the ATM link was clearly broken...

I pass this on as potentially useful info to people who have broadband
problems... at least you can 'phone a friend' and get them to use this to
see if YOU are currently suffering a known outage, or whether, as the
helpful BT man suggested, 'your router, she is obviously broken'.

:-)

It also allows you to see if your exchange is subject to a high
contention
ratio, and is therefore slower than it should be.

Enjoy, you sad nerds like me :-)


Brilliant info for u nerds on BT. Is there an equivalent diagnostic thingy
for ntl cabled broadband which is known as DSL?
Jim

I thought everyone was on BT (the infrastructure at least) - just like gas
and leccky you don't have another line installed.

Good info anyhow!


Off topic - Many years ago when privatisation was happening I was talking to
some guys and the mention of one of the electric companies suppling gas, one
guy said "how do they get it to you"? which followed the comment of "They
fit a special adapter on your electric cable and push the gas down the small
gap between the wires"

Paul

Dave wrote:
Andy Hall wrote:

On Wed, 25 Jan 2006 18:18:28 +0000, Alex wrote:


Jim Gregory wrote:

Brilliant info for u nerds on BT. Is there an equivalent diagnostic thingy
for ntl cabled broadband which is known as DSL?

Cable broadband is not DSL. ADSL is DSL.

Alex.



Neither of them are broadband, but that's another story.

Strictly "neither of them is broadband" if you're going to be
pedantic.

Agreed!

Quite why the term 'broad band' came into use in computers, I have no idea.

The use of two wires to connect to the internet is called a serial
connection. As such, it can never be specced as broad band. Broad band
is the ability of a signal to occupy a wider spectrum. As such, only a
modulated signal can be broad band. i.e. the data is not in a serial
stream, but is spread across a wide frequency.

What is called broad band, these days, is just a very fast serial
connection.

But the system used to provide ADSL *is* a high frequency signal
divided into pieces with each 'channel' used to carry data. Exactly
what you have described as 'broadband'.

It's most certainly not serial where all the 'bits' of data are sent
one after the other.

--
Chris Green

Dave wrote:
Andy Hall wrote:

Neither of them are broadband, but that's another story.


Agreed!


Not sure about that. My understanding is that the definition of
broadband is (something like) multiple different signals modulated onto
a single transmission medium. Therefore ADSL and Cable Internet are both
broadband.

Broadband is the opposite of baseband (as in 100BaseT Ethernet for example).

Ben.

Paul-S8 wrote:

I thought everyone was on BT (the infrastructure at least) - just like gas
and leccky you don't have another line installed.


Except those who have "cable" installed. It's just that, another cable,
not BT.

MBQ

Dave wrote:
Andy Hall wrote:

On Wed, 25 Jan 2006 18:18:28 +0000, Alex wrote:


Jim Gregory wrote:

Brilliant info for u nerds on BT. Is there an equivalent diagnostic thingy
for ntl cabled broadband which is known as DSL?

Cable broadband is not DSL. ADSL is DSL.

Alex.



Neither of them are broadband, but that's another story.

Agreed!

Quite why the term 'broad band' came into use in computers, I have no idea.

The use of two wires to connect to the internet is called a serial

Not in any normal sense of the term "serial" when applied to data
comms.

connection. As such, it can never be specced as broad band. Broad band
is the ability of a signal to occupy a wider spectrum. As such, only a
modulated signal can be broad band. i.e. the data is not in a serial
stream, but is spread across a wide frequency.

What is called broad band, these days, is just a very fast serial
connection.

I suggest you get a "broadband" connection and use it to do some
reading on how ADSL actually works. Google will be your friend here.

MBQ

On Thu, 26 Jan 2006 09:42:05 +0000, Ben Willcox
wrote:

Dave wrote:
Andy Hall wrote:

Neither of them are broadband, but that's another story.


Agreed!


Not sure about that. My understanding is that the definition of
broadband is (something like) multiple different signals modulated onto
a single transmission medium. Therefore ADSL and Cable Internet are both
broadband.

Broadband is the opposite of baseband (as in 100BaseT Ethernet for example).

Ben.


That is true as well. However, at the time that it was defined, the
technology having multiple signals modulated onto one medium was RF
cable, and "broad" was also used in the sense of having lots of
bandwidth. It was sold and used on the basis of being able to deliver
data, voice and proper video services.

While ADSL (together with POTS) can do voice and some degree of data,
it doesn't have the bandwidth to deliver proper broadcast TV quality
video.

Generally people don't derive their main video entertainment from
sitting in front of business card sized videos on a PC screen.

In that sense, the marketeers have massively overhyped ADSL.


--

..andy

Paul-S8 wrote:
"Jim Gregory" wrote in message
...

I thought everyone was on BT (the infrastructure at least) - just like gas
and leccky you don't have another line installed.


I'm not.

I've got Telewest, and (ICBW) they have all their own cables and things
in the street, and it comes into it's own box inside the house. I also
have a BT box in the hall however.

I remember when Telewest launched around here, I was doing GIS work for
Scottish Water and the amount of PU enquiries they generated (since
they laid cables in every street) was enormous.

--
Doug
"Doug's cool. He's metal " - Fnook
Ignore the old spamtrap work address; mail me on: doug at fruitloaf dot
net
http://suicidegirls.com/?hungrydoug

"Douglas de Lacey" wrote in message
...
Jim Gregory wrote:

Brilliant info for u nerds on BT. Is there an equivalent diagnostic
thingy for ntl cabled broadband which is known as DSL?

Ignoring your terminology,
http://homepage.ntlworld.com/robin.d.h.walker/cmtips/ is a good
starting-point for all things cable modem.

Douglas de Lacey

Thanx for that url, Doug.
BTW, a test on this reference calls a cabled service DSL, and ntl use
fibre-optical links to their distribution centres.
Jim

Andy Hall wrote:
The
higher speeds are only available very close to the exchange. 512k and
1Mb services are much more typical for most users.

2Mbit modems were around in the early 70's for telecoms purposes. The
range on a pair however was only around 1.5KM ( and at that point, the
signal was apparently lost in the noise and took a lot of effort to
recover it). I doubt that today is much different as the cables have
often not been changed. However, there's no reason not to use a fibre
cable to extend the range from the exchange to almost any distance you
wish. This leaves only the black box to customer range at 1.5KM for
2Mbits. I am intrigued by the thought of 8Mbits. I'd expect the range
from the fibre interface to be down in the 400M range, unless the modems
have increased tremendously in power.

Regards
Capitol

John Rumm wrote:
Dave wrote:

Neither of them are broadband, but that's another story.



Agreed!


I expect you are agreeing at crossed purposes! ;-)

The use of two wires to connect to the internet is called a serial


Erm... huh?

The connection between my TV and its aerial is with two wires... does
that make it serial also?

No. There is a centre core and an earth around that. That is a genuine
broad band connection, as it has width as well as serial data.

Having said the above, I can see where other posters are coming from.
But I have always seen a twisted pair as a serial link.

Dave

In message , The Natural
Philosopher writes
There was a major outage last week in BT's ATM network that caused I, and
others, to lose ADSL connectivity..

[big snip]

Enjoy, you sad nerds like me :-)


Guys, as interesting as it is, when was the last time any of you DIY'd
some ADSL exchange equipment ;-)

Take it to
alt.sad.nerds.broadband.excellent.service.checker. which.was.pointed.out.b
y.the.philospher or something :-)

--
Someone

Dave wrote:

No. There is a centre core and an earth around that. That is a genuine
broad band connection, as it has width as well as serial data.

Having said the above, I can see where other posters are coming from.
But I have always seen a twisted pair as a serial link.

Twisted pair can carry broadband in any sense of the word, so perhaps
your view needs a little tweaking!

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Fri, 27 Jan 2006 01:06:33 GMT, somebody
wrote:

In message , The Natural
Philosopher writes
There was a major outage last week in BT's ATM network that caused I, and
others, to lose ADSL connectivity..

[big snip]

Enjoy, you sad nerds like me :-)


Guys, as interesting as it is, when was the last time any of you DIY'd
some ADSL exchange equipment ;-)


I was doing things with some earlier this week.

So there.

Take it to
alt.sad.nerds.broadband.excellent.service.checker .which.was.pointed.out.b
y.the.philospher or something :-)

--

..andy

In article , Dave
writes

Broadcast FM transmissions use a broad band system. About 25 KiloHertz.

They use 75khz deviation plus the digital sub-carriers and stereo pilot
tone etc. Takes a bit above 100khz
--
Mr X

On Fri, 27 Jan 2006 01:06:33 -0000, somebody wrote:

In message , The Natural
Philosopher writes
There was a major outage last week in BT's ATM network that caused I,
and
others, to lose ADSL connectivity..

[big snip]

Enjoy, you sad nerds like me :-)


Guys, as interesting as it is, when was the last time any of you DIY'd
some ADSL exchange equipment ;-)


Last Sunday.

Take it to
alt.sad.nerds.broadband.excellent.service.checker. which.was.pointed.out.b
y.the.philospher or something :-)

On 27 Jan 2006 01:54:11 -0600, Mr X wrote:

In article , Dave
writes

Broadcast FM transmissions use a broad band system. About 25 KiloHertz.

They use 75khz deviation plus the digital sub-carriers and stereo pilot
tone etc. Takes a bit above 100khz

At least 250Khz for any fidelity, and 400 KHZ low phase delay is as good as
it gets. Butr isn;t good enough for todays crowded spectrum ... channels
are spaced as low as 100KHz overall, though adjacent transmitters are
suppoosed to not be closer than 300KHz IIRC.

On Fri, 27 Jan 2006 22:23:13 GMT, wrote:

On 27 Jan,
Mr X wrote:

In article , Dave
writes

Broadcast FM transmissions use a broad band system. About 25 KiloHertz.

They use 75khz deviation plus the digital sub-carriers and stereo pilot
tone etc. Takes a bit above 100khz

Maximum allowed deviation is 75 KHz. This /includes/ stereo pilot and RDS
modulation & anything else encoded. Bandwidth is in the region of 200KHz.

Its not maxiumum allowable. Its the normal deviation for 'full audio'. In
practice it goes a lot higher..and the full spectrum even at the rated
deviation is far higher..sidebands etc.