http://www.theregister.co.uk/2008/03...very_networks/

Interesting article, but I don't get the logic behind this bit:

"The cost of building and maintaining out a nationally distributed network
of servers [in each of the exchanges] would dwarf that sum.

The overriding fear must be that the telecoms industry, regulators and
government might pull their collective finger out and deploy fibre to the
home. Unlikely as that sounds right now, investment in a real
next-generation UK internet infrastructure could swiftly render a CDN next
to useless."

Do people here agree that FTTH being rolled out would make a CDN with
servers in all of the exchanges next to useless? Isn't the problem with the
bandwidth costs upstream of the exchanges due to the unique way the BT is
funded?


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

The adoption of DAB was the most incompetent technical
decision ever made in the history of UK broadcasting:
http://www.digitalradiotech.co.uk/da...ion_of_dab.htm

"DAB sounds worse than FM" <dab.is@dead> wrote in message
news:jY6Ej.7924$Ff4.4129@newsfe5-win.ntli.net...
It would make it more desirable IMO.
You would have to weigh up the costs of supporting the hardware in the
exchange vs. supporting it in central location + the extra core bandwidth.

Unless you are still talking about broadcast, then the BBC wouldn't need a
CDN.

dennis@home wrote:

Absolutely.



I did write in the thread subject "CDN for iPlayer"! You're not catching me
out that easy. ;-)

BTW, have I missed anything out from the following diagram for the route
that data would travel from the BBC to a user via an ISP:

http://www.digitalradiotech.co.uk/im...bc_to_user.gif

And from reading this about how BT charges:

http://community.plus.net/blog/2008/...t-of-ipstream/

If the BBC put storage into BT's exchanges, the ISPs shouldn't be charged a
penny should they? Because nothing would be going down the BT Central pipes,
which is where the ISPs have to pay BT for the bandwidth.

How much would you estimate it would cost the BBC to put storage into every
exchange in the country?



--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

The adoption of DAB was the most incompetent technical
decision ever made in the history of UK broadcasting:
http://www.digitalradiotech.co.uk/da...ion_of_dab.htm

DAB sounds worse than FM wrote:
That diagram looks about right, but at the same time is also wrong :-P

While the diagram shows the physical flow of data, it doesn't take into
account how the network is actually setup with regards to IP.

The ISP basically has a tunnel to each ADSL end-user, so the bit between
the data going into the central pipe and it appearing at the user
doesn't exist as a number of different blocks.

What this means is that currently data can't be injected along the way
or make short cuts. Two ADSL users on the same exchange who want to
transfer traffic have to have that traffic go all the way to the ISP
(over the central pipe, BT backbone, etc) and back again, even though it
might be the next port along on the same DSLAM.

If BT where to change the way the model works, then yes conceivably
there might not be a direct charge to the ISP for such data.

Stuart Clark wrote:

Fair enough. The diagram is to both show the data flow and to allow me to
explain how the ISPs are charged by BT, as described on here:

http://community.plus.net/blog/2008/...t-of-ipstream/

so I'll keep the BT bits in there.



Do you think the CDN "nodes" (or whatever they should be called) that the
BBC is proposing to put in each exchange would capture requests from users
that want to watch or listen to broadcast streams so that data wouldn't need
to go back to BT? That sounds simple in theory, but would it be easy to do
this in practice? Is there much "intelligence" in the exchanges? I suppose
at the end of the day, it's only a few IP packets anyway, so it probably
wouldn't matter one way or the other.

What about if the BBC sent all of its multicast streams directly to each
exchange via BT or via an LLU rather than them having to go to each ISP
first? Would that work? If the BBC has got equipment in each exchange it
seems a bit of a waste of time sending their channels to every ISP when they
could go straight to each exchange.



Okay.


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

The adoption of DAB was the most incompetent technical
decision ever made in the history of UK broadcasting:
http://www.digitalradiotech.co.uk/da...ion_of_dab.htm

DAB sounds worse than FM wrote:

As things currently stand there isn't really any intelligence in the
network at all. Things actually used to be "better" in some senses
before the tunnels setup happened, as traffic between ADSL users didn't
have to go via the ISP and was therefore "free".

With regards to the BBC, I would imagine it would depend what they agree
with BT (presumably Openreach or Wholesale) as to how it would work &
how much it would cost. It would need some adjustment to the current
model used (ISP straight to ADSL user).

Stuart Clark wrote:

If BT tried to charge the BBC an arm and a leg, what do you reckon the
chances are of the BBC being allowed to put a satellite dish on the roof of
every exchange to avoid having to pay BT a penny?

BTW, what's the bandwidth going into a typical suburban exchange?


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

The adoption of DAB was the most incompetent technical
decision ever made in the history of UK broadcasting:
http://www.digitalradiotech.co.uk/da...ion_of_dab.htm

DAB sounds worse than FM wrote:
That isn't going to help, as BT own the exchange and so would charge for
that too!

"DAB sounds worse than FM" <dab.is@dead> wrote in message
news:vgjEj.4326$Ge4.3556@newsfe1-win.ntli.net...
BT will just charge the BBC the going rate, the same as any LLU supplier.
It may not do the BBC any good of course if the traffic has to go back up to
the ISP and then back down again to get to the subscriber.

Also BT is currently doing away with exchanges.. this is what 21cn is really
about in case you have missed the point.
There wont be any small exchanges at all, all the equipment can be moved
into street cabinets and the buildings sold.
Its already happening.. my local exchange is now a hotel so what are the
chances the BBc can put their stuff in the hotel?
(Back to the disks and stuff in the DSLAMs again.)

A few dozen fibers, probably six into each new green cabinet.

Stuart Clark wrote:

How much though?


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

The adoption of DAB was the most incompetent technical
decision ever made in the history of UK broadcasting:
http://www.digitalradiotech.co.uk/da...ion_of_dab.htm

dennis@home wrote:

Obviously I have, because all I've read is that it was to replace lots of
old systems with one run over IP to simplify everything.



Slim.



The satellite idea was just to enable multicast to be done cheaply if BT
doesn't play ball - you can't deliver iPlayer on-demand content via
satellite...



So could VDSL2 be implemented without any digging up of any roads, or would
they need to put in more fibre? And if the latter, would they have to lay a
lot of new fibre or not a lot?


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

The adoption of DAB was the most incompetent technical
decision ever made in the history of UK broadcasting:
http://www.digitalradiotech.co.uk/da...ion_of_dab.htm

"DAB sounds worse than FM" <dab.is@dead> wrote in message
news:jytEj.506$4f4.116@newsfe6-win.ntli.net...
Sky do anytime over satellite, download stuff to the disks in sky+ at night.

New fiber.. the existing stuff terminates too far away for VDSL for most
people, although I could probably get 50M if someone wants to put the card
in the DSLAM for me.

On 20/03/2008 13:20, DAB sounds worse than FM wrote:

If BT worked out what it would be used for, and how much they'd loose by
allowing it compared to whatever service they might otherwise be able to
sell, then the charge would be remarkably similar to that product, of
course then they'd add "excess construction charges" :-)

dennis@home wrote:

I was talking about the possibility of delivering data to the exchanges via
satellite instead of using multicast, and the receivers in the exchange
would simply pass the data on to users via DSL.



Does this statistic of >80% of households live within 5,000 feet loop length
from the exchange also apply to the UK:

http://www.convergedigest.com/images...119-ikanos.gif

Does anyone know what the statistics are for loop lengths in the UK?


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

The adoption of DAB was the most incompetent technical
decision ever made in the history of UK broadcasting:
http://www.digitalradiotech.co.uk/da...ion_of_dab.htm

Andy Burns wrote:

I saw someone semi-sarcastically suggest that BT should be renationalised,
and I'm beginning to wonder whether that would be a good idea!


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

The adoption of DAB was the most incompetent technical
decision ever made in the history of UK broadcasting:
http://www.digitalradiotech.co.uk/da...ion_of_dab.htm

DAB sounds worse than FM wrote:

The local loop would not exist in far flung places if the original BT
charter wasn't 'a line to anyone who wants it at a fixed price'


Including the channel islands, etc..

"DAB sounds worse than FM" <dab.is@dead> wrote in message
news:L9OEj.4601$Ge4.4146@newsfe1-win.ntli.net...
8<

You also need to recode the video stream to match the DSL speeds somewhere.
If its a dedicated sat then you can do it prior to transmission if not you
have to do it in the exchange. Normal sat and freeview is not suitable for
DSL use being variable bit rate and very peaky.

8<

Yes!
Its valuable information too.

"DAB sounds worse than FM" <dab.is@dead> wrote in message
news:GiOEj.14732$jH5.3765@newsfe3-win.ntli.net...
BT was dreadful when it was nationalised from a customer point of view.
It may have been better for British industry though.

The Natural Philosopher wrote:

Fair enough.



I wish they'd have put something in the charter about rolling FTTH out as
well, because if we go to VDSL2 first whilst everyone else goes straight to
fibre we'll be the laughing stock of the developed world.


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

The adoption of DAB was the most incompetent technical
decision ever made in the history of UK broadcasting:
http://www.digitalradiotech.co.uk/da...ion_of_dab.htm