[AusNOG] Discussion point: Why aren't the NBNCo tails symmetric in speed?

Tony Wicks tony at wicks.co.nz
Wed Apr 9 08:18:11 EST 2014


Actually the difference in cost of delivery of GPON vs point to point is
very substantial. Also, DWDM-PON is possible now and will come down to the
cost of GPON by the time most fibre rollouts are physically complete.
DWDM-PON uses a separate wavelength for each ONT and so is far more
efficient than dragging a physical fibre from every end user back to the
cabinet/exchange. As such deploying point to point physical fibre now would
be a massive waste of capital.

 

From: AusNOG [mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Colin
Stubbs
Sent: Wednesday, 9 April 2014 9:29 a.m.
To: Skeeve Stevens
Cc: ausnog at ausnog.net
Subject: Re: [AusNOG] Discussion point: Why aren't the NBNCo tails symmetric
in speed?

 

Have a read of this Skeeve,

 

http://static.googleusercontent.com/media/research.google.com/en//pubs/archi
ve/36936.pdf
<http://static.googleusercontent.com/media/research.google.com/en/pubs/archi
ve/36936.pdf> 

 

Obviously written while they were still testing and reviewing their options,
but they were leaning towards point to point delivery already.

 

Makes sense to me. WDM-PON standards weren't and still are not ready yet,
and Google isn't the type of company to screw around trying to save a few
dollars for short term gains.

 

-Colin

 

 

On 9 April 2014 06:38, Skeeve Stevens <skeeve+ausnog at eintellegonetworks.com
<mailto:skeeve+ausnog at eintellegonetworks.com> > wrote:

Yes, but how does that matter?

 

Google Fiber also uses GPON and they are delivering 1G/1G (see:
http://networkmatter.com/2014/02/27/google-fibers-brewing-little-secret-expo
sed-its-gpon/)

 

While GPON may be asymmetrical for the end tail, the speeds it can achieve
are clearly symmetrical in nature... and the speeds that can be achieved
means that there is no reason at all that 100/100, 50/50, 25/25 or 12/12
can't be achieved - with no material impact to the network utilisation or
cost.

 

Still sounds like an artificial restriction to me. 


...Skeeve

 

Skeeve Stevens - eintellego Networks Pty Ltd

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On Wed, Apr 9, 2014 at 2:02 AM, Damian Guppy <the.damo at gmail.com
<mailto:the.damo at gmail.com> > wrote:

NBN is built on GPON tech, which is normally asymmetrical. I believe it is
ITU-T G.984 which supports 2.488Gbit/s down and 1.244Git/s up.  Most home
users have an asymmetrical data requirement, so it makes sense to divide up
the available spectrum with a bias to downstream. Same reason ADSL is used
and is asymmetrical even through there are SDSL specs out there. 

 

--Damian

 

On Mon, Apr 7, 2014 at 6:52 PM, Skeeve Stevens
<skeeve+ausnog at eintellegonetworks.com
<mailto:skeeve+ausnog at eintellegonetworks.com> > wrote:

Hey all,

 

I am sure this will spurn a healthy discussion... perhaps with conflicting
views...

 

But I was wondering the other day 'Why aren't NBNCo tails sold as symmetric
speeds?'

 

Considering:

 

- The transit the RSP buys is symmetric (nearly always)

- The network core of the RSP is symmetric

- The handoff to either NBNCo or an aggregator (and then NBNCo) is pretty
much always symmetric

- The PoI's core is symmetric

- The fibre to the home is symmetric capable

- The NTU is just ethernet - symmetric

- Anything they plug into the NTU is symmetrical - ethernet

 

Google Fibre in the US is 1G/1G in speeds... 

 

So... unless I am missing something obvious (always possible)... Why are
NBNCo tails not sold as symmetrical speeds?

 

I am not sure why there is this artificial design in these products to make
them asymmetric.  There doesn't seem to be any gain by doing this that I can
think of.

 

Gone are the days of DSL like speeds and unbalanced design... even ATM was
symmetrical.

 

Keen for peoples opinions.



...Skeeve

 

Skeeve Stevens - eintellego Networks Pty Ltd

 <mailto:skeeve at eintellegonetworks.com> skeeve at eintellegonetworks.com ;
<http://www.eintellegonetworks.com/> www.eintellegonetworks.com

Phone:  <tel:1300%20239%20038> 1300 239 038; Cell
<tel:%2B61%20%280%29414%20753%20383> +61 (0)414 753 383 ; skype://skeeve

 <http://facebook.com/eintellegonetworks> facebook.com/eintellegonetworks ;
<http://linkedin.com/in/skeeve> linkedin.com/in/skeeve 

 <http://twitter.com/theispguy> twitter.com/theispguy ; blog:
<http://www.theispguy.com/> www.theispguy.com

  <http://eintellegonetworks.com/logos/ein09.png> 

The Experts Who The Experts Call

Juniper - Cisco - Cloud - Consulting - IPv4 Brokering


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