[AusNOG] "The NBN" will run on copper for *ever*

[PRK]

On 2014-07-11 17:37, jake anderson wrote:

> I always wondered why they never offered VDSL for customers closer
> than 800m or so.
> I mean it wouldn't cost them a *great* deal to add a few vdsl
> linecards to the mix.

Some assumptions made in the above comment are:

1) The DSLAM equipment supports different line cards.
2) There's an "optimum" balance of VDSL vs ADSL vs SHDSL line cards to 
pre-populate a particular site with (the ISP doesn't want to be 
returning each week / month).
3) The ISP can wire someone to an appropriate port either during 
provisioning, or via some sort of active switching in the DSLAM (upgrade 
from ADSL to VDSL).

You'd think they'd all play out, but surprisingly not.

There are challenges, particularly if an ISP has started deploying 
DSLAMs with ADSL2/2+ line cards, and then the vendor comes along with a 
VDSL line card which doesn't fit in the same chassis.

At that stage, the ISP needs to deploy new chassis (some ADSL, some VDSL 
chassis in each exchange), or the ISP takes a look at their customer 
profile and goes "bugger it, there's not enough density to make a 
dedicated VDSL chassis worthwhile, so we're better off using the 
exchange space for ADSL DSLAMs".

If the ISP's vendor uses a significantly different platform for VDSL, 
the ISP then needs to decide if it wants to operate and support multiple 
platforms, and work out how to deal with feature parity.

There are also the various VDSL cross talk issues - last time I looked 
(many years ago) it wasn't approved for use on the Telstra CAN, but that 
may well have changed.

But basically, it's not always as easy as just "add a few vdsl line 
cards to the mix" :)

prk.