[LINK] Congestion (was Re: NBN to cost 24 times South Korea's faster network, says research body)

[Paul Brooks]

On 12/02/2011 2:56 PM, David Boxall wrote:
> On 11/02/2011 5:33 PM, Fernando Cassia wrote:
>> On Fri, Feb 11, 2011 at 2:47 AM, David Boxall
>> <david.boxall at hunterlink.net.au>  wrote:
>>> As far as I know, for broadcast substitution, they're not suggesting IP.
>>>
>>> Bear in mind that DTV performs poorly in the regions. Where fibre is
>>> available, it will be far more cost-effective than the subsidised
>>> satellite we (taxpayers) will otherwise be paying for.
>> I´m still confused. "broadcast substitution" means doing the "last
>> mile" to the TV viewer over fibre, rather than air? (DTT, UHF)?.
> ...
> Why confused? Hasn't part of the logic of the NBN always been to provide 
> an alternative transmission medium, so that spectrum may be freed for 
> other uses? After all, we can lay more fibre, but we can't make more 
> spectrum.
The NBN has not been directly set up to provide an alternative method of accessing the
free-to-air TV programming (analogue or digital), and I don't recall 'freeing digital
TV spectrum' being in any of the justifications for the NBN.

It won't have a RF-overlay capability, so any television-like service will be set up
as a multicast IPTV service, from a service provider.
I don't know if any of the tradiutional broadcasters are looking to also send their
signal over the NBN, and I rather suspect the system will be set up so that a
set-top-box can only access a single provider at a time - so FTA TV is likely to only
be accessed through a pay service along with a stack of other pay-tv channels. I don't
know of any organisation - including government - that might be looking to put
together all the required head-end kit to put together a FTV-only service for free
that could be the fibre-cable-equivalent of the digital radio transmissions.

Note also that as far as the NBN is concerned, 'multicast' is ethernet multicast, not
IP multicast (although the two layers might need to be connected), and the multicast
capability might well be unidirectional - from the PoI towards the user, not from
user-to-user.
> I'm told the situation is similar in parts of Sydney. That's just one 
> area where the NBN will solve a problem that isn't getting a lot of 
> attention.
If the problem is 'can't get digital television for free', I rather suspect the NBN
won't solve that problem.

Paul