Hi Thing,

ADSL is duplex and I think cable is too. ADSL uses different frequency bands for upstream and downstream traffic - 300hz to 4Khz for POTS, 24Khz to 136Khz for Upstream and 136Khz to 1.1Mhz for downstream. Interference generally effects the upper frequency range first so you will see the downstream rate drop off faster than the upstream. RADSL (Rate-adaptive ADSL) further breaks those bands into sub channels.

Crosstalk is an issue in some cables but the latest xDSL technology is very good at filtering crosstalk and will only get better. The biggest issue with crosstalk is the noise it can cause on adjacent voice pairs not adjacent ADSL enabled pairs.

Some of the copper in the ground is fairly shocking, especially the older paper insulated stuff, but those are just things we will have to work with. This is not a perfect solution and we do not claim it will work for everyone.

ADSL does not have a bottleneck between the customer and the exchange / CO and the DSLAMs / backbone infrastructure can be scaled as required, hence usage charging. The biggest bottlenecks will always be the sites you are trying to reach and the international bandwidth.

On a personal note...
I am actively passing your feedback through to the people who need to know and it is already having a positive effect on the direction this service will take. Remember a large number of the users on this trial are Telecom staff and some of us are power users too!
We are equally keen to find the issues and ensure this delivers what a majority of people want (this makes good business sense and helps us provide our shareholders with a return on their investment - you can buy shares too if you want!). Good business is a combination of the right product at the right price at the right time. That is what myself and the other 8000+ people who work for Telecom are trying to deliver and our jobs rely on us achieving that.

Also remember it is not only the raw cost of the equipment / network / bandwidth etc... that make up the cost of delivering a service like this! There is also the expertise / time of the people involved. There is a massive amount of time being spent by people all over Telecom from virtually every major business group in the development of the processes and systems to support this network.

The ADSL trials to date have seen a great many changes and this is due to the rapidly changing technology / economy / culture that we have today. We are actively searching for the best solutions and your feedback is invaluable and taken on board so keep it coming.

I almost never wear a suit to work!
I am doing this because I love my job and it pays really well (I work 60+ hours a week and deserve every cent!)
My CV is definitely going to be enhanced by the experience this contract is providing me with!

Mark 8-)

>>> "Thing" <linux@xtra.co.nz> 5/May/1999 10:36pm >>>

-----Original Message-----
From: Mark Barlow <Mark.Barlow@telecom.co.nz>
To: adsl@freebsddiary.cx <adsl@freebsddiary.cx>
Date: 05 May 1999 18:44
Subject: RE: ADSL - charging structures -Reply -Reply

>First I'm not trying to knock Saturn.
>Second these are my personal opinions.
>
>Unlike ADSL where you have a dedicated connection to your home, cable is a
shared media and you share the 2Mbps (I had heard their network was carrying
34Mbps of bandwidth?!)

Not true, in a strict sense, adsl has I assume cross talk problesm which
worsen with disstance and use, at present there are few adsl users, when
there are lots all causing hi frequency distortion and cross talk adsl may
actually be worse.

with whoever else is using your segment.

With adsl i could be sharing with 200 + ppl on unshielded twisted pair of
dubious quality particulary in the wet.

This doesn't matter when there are few people on the segment, but can cause
congestion when the numbers increase.

Ditto ADSL.

>With ADSL we use traffic shaping to ensure everyone gets a fair byte (ha
ha!) of the bandwidth pie, but with a shared media you can only traffic
shape down to a segment level. This means if you have several 'Power Users'
(which most early adopters are! - you included!!) on a segment, then
everyone else will have their throughput cut. It works in a very similar
fashion to ethernet - the more users on a segment, the more collisions and
lower performance.

I suspect so will adsl i dont consider your argument correct, also ethernet
is or can be duplex, adsl isnt(?) is cable? i thought it was.
>
>It is really comes down to how much you want to spend and what performance
you are looking for. Their prices are good though and I hope it spurs our
marketing department into the competitive spirit!

Mark with the best will in the world 'techies' dont count 'suits' do and
'suits' only see $ and only usually short term as they are looking to add to
their CV and move on......god i hate my suit........

:)

Thing

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Received on Thu May 6 13:09:03 1999