[AusNOG] Strange ADSL problem - troubleshooting / diagnosis advice wanted

[Paul Brooks]

On 10/09/2014 3:28 PM, Jeremy Visser wrote:
> On 10/09/14 14:39, Paul Brooks wrote:
>> 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.
> 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.

Its actually goes back to ADSL2:

G.992.5 Jan 2009  ADSL2+

https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-G.992.5-200901-I!!ZPF-E&type=items


Page 'ii':
This Recommendation defines several optional capabilities and features:
– transport of STM and/or ATM and/or Packets;
– transport of a network timing reference;
– multiple latency paths;
– multiple frame bearers;
– short initialization procedure;
*– dynamic rate repartitioning;**
**– seamless rate adaptation;*
- extended impulse noise protection;
- erasure decoding;
- virtual noise;
- impulse noise monitor.
"

G.992.3 April 2009 ADSL2:

https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-G.992.3-200904-I!!ZPF-E&type=items

Page 'ii':
"This Recommendation defines several optional capabilities and features:
• transport of STM and/or ATM and/or Packets;
• transport of a network timing reference;
• multiple latency paths;
• multiple frame bearers;
• short initialization procedure;
*• dynamic rate repartitioning;**
**• seamless rate adaptation;*
• extended impulse noise protection;
• erasure decoding;
• virtual noise;
• impulse noise monitor."

"Relative to Recommendation ITU-T G.992.1, the following PMD-related features have
been added:
• New line diagnostics procedures available for both successful and unsuccessful
initialization
scenarios, loop characterization and trouble-shooting.
*• Enhanced on-line reconfiguration capabilities including bitswaps and seamless rate
adaptation.**
**• Optional short initialization sequence for recovery from errors or fast resumption
of operation.**
**• Optional seamless rate adaptation with line rate changes during showtime.*"

Clause 8.16:
"8.16 On-line reconfiguration of the PMD function
On-line reconfiguration of the PMD function is intended to allow changes in the
control parameters
without interruption of service and without errors (i.e., bitswap, dynamic rate
repartitioning and
seamless rate adaptation)."

VDSL2 doesn't really add much functionality to ADSL2 other than the vastly expanded
frequency range.

cheers...

Paul.




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