[LINK] RFI: ADLS2+ Performance

TKoltai tomk at unwired.com.au
Thu Jul 5 16:47:41 AEST 2012

> -----Original Message-----
> From: link-bounces at mailman.anu.edu.au 
> [mailto:link-bounces at mailman.anu.edu.au] On Behalf Of Roger Clarke
> Sent: Thursday, 5 July 2012 3:44 PM
> To: link at anu.edu.au
> Subject: [LINK] RFI: ADLS2+ Performance
> I've had major problems with TPG's ADSL2+ service during the 
> last 2 months.
> That's after 'Jerome', presumably in Manila, "increased the 
> signal-to-noise ratio [on the DSLAM] at the exchange".
> Can anyone explain, or point to an explanation of, what that 
> really means?
> Thanks, as always!

Signal to noise ratio...  (Could be a couple of things... Signalling
and/or overselling)

Copper phone lines are of different gages, insulating properties and
lengths. Therefore the signal between the exchange and your DSL modem
attenuate at different frequencies depending on all these aspects. 

When many different modems (all attenuating different signal strengths)
are all attached to the same DSLAM, fine tuning the aggregate "signal"
can be a headache.

Or another way of looking at it is the number of other ports on the
DSLAM that is accepting traffic for your pots exchange area (mixed for
reasons of economy) with other exchange areas utilising different data
channel signalling to your modem brand ADSL type and plan.

As an aside, last June, I suggested that by April 2012 the overseas
bandwidth capacity of PPC-1 would be full and continuing Internet
utilisation would again be determined by Telstra (who have 1 Tb of Dark
fibre unlit on Endeavour).

Alternatives are as growing caching system that places further load on
already bursting at the seams backhaul path network - which can overload
old switches that are time slicing as opposed to multi processing.

The ADSL problem is further exasperated by the merger of Chime, iiNet,
Netspace, and internode, giving young Michael a logistical headache of
needing to merge incompatible billing and switching systems together
whilst fighting a rearguard action on NBN sale incursions into his DSL
Therefore, during the NBN roll-out expect noise to signal ratio to
"increase" as the older technology is bandaided rather than upgraded or
Curiously, Telstra recognised this upcoming problem and have spent
millions upgrading ADSL2+ with their Tophat initiative. Therefore
generally Telstra CAN ADSL resellers should (for a change) generally
provide more signal with less "noise".

With the exception of Telstra, All of the carriers buy each others
"ports" to service customers seamlessly, however, sometimes, problem
ports are accidentally rented out, rather than repaired...

The dropouts are caused by oversale of the ports on a DSLAM. (Just like
the heady dotcom days where the free ISP's might have 100 users all
vying for use on a solitary modem.

By altering their timeouts to shorter and shorter number of seconds,
more and more users can be allocated to the same DSLAM.


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