[LINK] tRe: NBN white-elephant-to-be ...
Paul Brooks
pbrooks-link at layer10.com.au
Thu Aug 26 15:53:24 AEST 2010
On 26/08/2010 3:05 PM, Kim Holburn wrote:
>
> Here is an article that reckons that we could get 10Gb out of our
> current copper. Written in 2006 it doesn't seem to have eventuated.
> http://arstechnica.com/hardware/news/2006/10/7952.ars
>
Note thats 10Gbps aggregate over 50 Cat-3 twisted pairs - not on each one.
I looked at this a lot a couple of years ago, while we were trying to get VDSL2
permitted in Australia.
Yes, with DSM theoretical models, and even some real-world demonstrations, they could
get up to 200 Mbps on a single copper pair - a form of VDSL2 on steroids.
Here is a link to a vendor field trial (requires registration):
http://www.alcatel-lucent.com/wps/PA_1_A_9C1/DocumentDownloadFormServlet?LMSG_CABINET=Docs_and_Resource_Ctr&LMSG_CONTENT_FILE=White_Papers/DLM_WP.pdf&lu_lang_code=en_WW
and another field trial result: http://www.lightreading.com/document.asp?doc_id=173580
Look up 'vectoring DSM VDSL2' in your favourite search site and you'll find many
articles about the technique.
In the latter case, they achieved 500 Mbps - at a distance of 500 metres, using 6
parallel pairs, or a bit over 80 Mbps per pair.
Such speeds are achieved over very short lengths - a few hundred metres at best - and
depend on having every pair connected to the same line-card on the same DSLAM operated
by the same company - goodbye ULLS, and competitive DSLAMS.
> Note that the potential bandwidth of fibre is much, much greater than
> this. I think people have got 69Tb (Terrabits) out of a single fibre
> 240Km long. I expect that we will be able to get several orders of
> magnitude better than that in the future.
In real world deployments people are getting 10 Gbps per user in WDM-PON deployments
now, and 100 Gbps per user won't be too far away now the IEEE has standardised those
physical interfaces.
/straightface - Pretty hard to get a copper pair to do that, let alone to a distance
of 20 kilometres.
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