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<div class="moz-cite-prefix">On 10/09/2014 3:28 PM, Jeremy Visser
wrote:<br>
</div>
<blockquote cite="mid:540FE199.9070408@visser.name" type="cite">
<pre wrap="">On 10/09/14 14:39, Paul Brooks wrote:
</pre>
<blockquote type="cite">
<pre wrap="">ADSL2+ is supposed to re-train to a new sync rate seamlessly without
packet drops, whereas the older ADSL1 had to effectively drop the
line, re-sync, generate a new bitfield table per tone to cope with
changes to background noise and cross-talk that caused a need for a
re-sync.
</pre>
</blockquote>
<pre wrap="">
I thought that was a feature of VDSL2, not ADSL2+.
I’d be interested to see a source on that as happy to be wrong.</pre>
</blockquote>
<br>
Its actually goes back to ADSL2:<br>
<br>
G.992.5 Jan 2009 ADSL2+<br>
<br>
<a class="moz-txt-link-freetext" href="https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-G.992.5-200901-I!!ZPF-E&type=items">https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-G.992.5-200901-I!!ZPF-E&type=items</a><br>
<br>
<br>
Page 'ii':<br>
This Recommendation defines several optional capabilities and
features:<br>
– transport of STM and/or ATM and/or Packets;<br>
– transport of a network timing reference;<br>
– multiple latency paths;<br>
– multiple frame bearers;<br>
– short initialization procedure;<br>
<b>– dynamic rate repartitioning;</b><b><br>
</b><b>– seamless rate adaptation;</b><br>
- extended impulse noise protection;<br>
- erasure decoding;<br>
- virtual noise;<br>
- impulse noise monitor.<br>
"<br>
<br>
G.992.3 April 2009 ADSL2:<br>
<br>
<a class="moz-txt-link-freetext" href="https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-G.992.3-200904-I!!ZPF-E&type=items">https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-G.992.3-200904-I!!ZPF-E&type=items</a><br>
<br>
Page 'ii':<br>
"This Recommendation defines several optional capabilities and
features:<br>
• transport of STM and/or ATM and/or Packets;<br>
• transport of a network timing reference;<br>
• multiple latency paths;<br>
• multiple frame bearers;<br>
• short initialization procedure;<br>
<b>• dynamic rate repartitioning;</b><b><br>
</b><b>• seamless rate adaptation;</b><br>
• extended impulse noise protection;<br>
• erasure decoding;<br>
• virtual noise;<br>
• impulse noise monitor."<br>
<br>
"Relative to Recommendation ITU-T G.992.1, the following PMD-related
features have been added:<br>
• New line diagnostics procedures available for both successful and
unsuccessful initialization<br>
scenarios, loop characterization and trouble-shooting.<br>
<b>• Enhanced on-line reconfiguration capabilities including
bitswaps and seamless rate adaptation.</b><b><br>
</b><b>• Optional short initialization sequence for recovery from
errors or fast resumption of operation.</b><b><br>
</b><b>• Optional seamless rate adaptation with line rate changes
during showtime.</b>"<br>
<br>
Clause 8.16:<br>
"8.16 On-line reconfiguration of the PMD function<br>
On-line reconfiguration of the PMD function is intended to allow
changes in the control parameters<br>
without interruption of service and without errors (i.e., bitswap,
dynamic rate repartitioning and<br>
seamless rate adaptation)."<br>
<br>
VDSL2 doesn't really add much functionality to ADSL2 other than the
vastly expanded frequency range.<br>
<br>
cheers...<br>
<br>
Paul.<br>
<br>
<br>
<br>
<br>
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