[AusNOG] Looks like the NBN will be a PON variant for sure...

Colwell, Scott scott.colwell at nn.com.au
Wed Apr 29 14:51:01 EST 2009

I see that most of the value to AU of building the NBN is not delivering
residential internet but in having
an access network that can deliver a decent rate at a decent price.
Most of the value (meaning valuable
to society) will be private networks of some sort (e.g your local doctor
being able to show your x-ray to
the specialist etc.)
Better to do this lower in the stack rather than running VPN over
Internet (e.g. do it at L2.)  Plus then you
find it easier to wholesale....  Make it scalable by connecting the OLTs
(and whatever other broadband access
nodes you care to deploy such as DSLAMs, WiMax nodes etc) to an MPLS
backhaul network that provides
per retailer L2 or L3 backhaul VPNs.  Hell, the OLTs etc don't even have
to be owned by NBN Corp as long as they
meet a minimum set of capabilities!
The last thing I want to see is an NBN built over a flat IP network.  I
guess I could run GRE tunnels with
an MPLS shim inside that to provide a flexible transport but then I have
to worry about the final MTU.  Please
don't send us down a path to RFC4623 pseudowire fragmentation and
(who has been delivering 802.3 EPON for a couple of years now...)


	From: ausnog-bounces at lists.ausnog.net
[mailto:ausnog-bounces at lists.ausnog.net] On Behalf Of Rob Wise
	Sent: Wednesday, 29 April 2009 1:55 PM
	To: ausnog at ausnog.net
	Subject: Re: [AusNOG] Looks like the NBN will be a PON variant
for sure...
	On Wed, Apr 29, 2009 at 10:12 AM, Mark Smith
<marksmith at adam.com.au> wrote:

		Nick Brown wrote:
		> Because from an ISP operational perspective thats a
horrible thought?
		> You lose the ability to shape / count / monitor
traffic, in addition to
		> the increased support because Joe next door has been
browsing someone
		> else's $c share.
		Look up "IPoE" in Google (as silly as the acronym is),
all those
		problems have or are being solved (e.g. cable networks
use DHCP, and all
		the Ericsson DSLAMs that a lot of ISPs have are (and
have been for a
		long time) "IPoE" capable)). Cisco's ISG product can
apparently turn
		DHCP leases into RADIUS accounting records for example.

	The extensive use of PPPoE/A and LAC/LNS in Australia is largely
due to the monopoly carrier situation and the requirement for wholesale
access (IMHO).  In many other countries DHCP-based access is far more
common than PPP and all the usual features like Radius, shaping, ACLs,
etc are still available.  I'd be surprised if you found a router vendor
which did not support DHCP based subscribers these days. 

		In a "native", not wholesale ADSL environment, the 8
byte per-packet
		overhead and BRAS processing load, MTU issues and
hair-pinning of PPPoE
		encapsulated traffic are very expensive, when you
consider that the only
		real purpose of converting a multi-access medium like
Ethernet into a
		point-to-point virtual link is to be able to
authenticate the user. If
		you already know where they live (and DSLAMS can insert
that circuit-id
		in DHCP requests), why do you care what username /
password they use?

	Another model that is common is for each access port on the
DSLAM / ONT to be assigned a different VLAN on the trunk to the BRAS.
This can also allow for wholesale access by carrying the VLAN all the
way through to the retail provider at layer 2.  With a PON it would be
quite easy to have multiple retailers access the same household and
break out on different ethernet ports on the back the ONT.  Eg, internet
on port 1, IPTV on port 2, voice on port 3, etc.  The household could
potentially take all these services from different retail providers.
	(who was setting up a PON in the lab last week)

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