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

Wed Apr 9 07:13:51 EST 2014

That link below does not seem authoritative as to how Google may or may not
be delivering symmetric service, they may be using point to point where they
do that. GPON as a rule is asymmetric as the upstream portion can be thought
of as TDM. I.E. the 1+gig uplink bandwidth is split into slices that are
dedicated to each of the ONT's on the split. Downstream is encrypted and
delivered to all ONT's on the split so can be thought of more as statistical
multiplexing (sort of).

From: AusNOG [mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Skeeve
Stevens
Sent: Wednesday, 9 April 2014 8:39 a.m.
To: Damian Guppy
Cc: ausnog at ausnog.net
Subject: Re: [AusNOG] Discussion point: Why aren't the NBNCo tails symmetric
in speed?

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

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

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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

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

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

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

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