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<p class="MsoNormal"><span style="color:#1F497D">Lana,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">This was a decision made early on in the development of SAS packet mode.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">For SAS dword mode, the scrambler was closely linked to the connections. The scrambler is reset on each SOF as originally defined by SATA.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">For SAS packet mode it was determined that the scrambler should be reset on a more random basis, so that if a Retry event occurred, then the data being transmitted would be encoded differently each time. Without
 the benefit of 8b10b encoding, the transmitted packet mode data can have long run lengths of zeros or ones without a transition. The objective is to avoid repeating an unfortunate alignment of the scrambler pattern with the actual data. Defining the scrambler
 to be free-running allows designs to separate encoding of the link events from the scrambler.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p>&nbsp;</o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I hope this helps to give insight into the decision for a free running scrambler.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p>&nbsp;</o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Regards<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Tim Symons. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p>&nbsp;</o:p></span></p>
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<p class="MsoNormal"><b>From:</b> t10-bounces@t10.org [mailto:t10-bounces@t10.org]
<b>On Behalf Of </b>Lana Chan<br>
<b>Sent:</b> Wednesday, October 12, 2016 12:24 PM<br>
<b>To:</b> t10@t10.org<br>
<b>Subject:</b> [T10] [SPL-4] Query Regarding Scrambling in Packet Mode<o:p></o:p></p>
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<p class="MsoNormal"><o:p>&nbsp;</o:p></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:14.0pt;font-family:&quot;Cambria&quot;,serif;color:red">EXTERNAL EMAIL</span><span style="font-size:12.0pt;font-family:&quot;Times New Roman&quot;,serif"><o:p></o:p></span></p>
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<p class="MsoNormal">Hello,<o:p></o:p></p>
<p class="MsoNormal">I have query regarding the behavior of scrambling in packet mode:<o:p></o:p></p>
<p class="MsoNormal"><o:p>&nbsp;</o:p></p>
<p class="MsoNormal">Scrambling in Dword mode :- <o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:38.5pt;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="font-family:Symbol"><span style="mso-list:Ignore">&middot;<span style="font:7.0pt &quot;Times New Roman&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
</span></span></span><![endif]>As per protocol, any <b>primitive</b> transmission in Dword mode happen without scrambling and
<span style="background:yellow;mso-highlight:yellow">without advancing the scrambler</span>.<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:38.5pt">Please refer section <b><span style="font-size:10.0pt;font-family:Arial-BoldMT">6.8.2 Scrambling while in the SAS dword mode
<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:Arial-BoldMT"><o:p>&nbsp;</o:p></span></b></p>
<p class="MsoNormal">Scrambling in Packet mode :- <o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:38.5pt;text-indent:-.25in;mso-list:l0 level1 lfo2">
<![if !supportLists]><span style="font-family:Symbol"><span style="mso-list:Ignore">&middot;<span style="font:7.0pt &quot;Times New Roman&quot;">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
</span></span></span><![endif]>As per protocol, any <b>primitive</b> transmission in packet mode happen without scrambling but
<span style="background:yellow;mso-highlight:yellow">with advancing the scrambler</span>.<o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:38.5pt">Please refer section<b><span style="font-size:10.0pt;font-family:Arial-BoldMT"> 6.8.3 Scrambling while in the SAS packet mode<o:p></o:p></span></b></p>
<p class="MsoListParagraph" style="margin-left:38.5pt"><b><span style="font-size:10.0pt;font-family:Arial-BoldMT"><o:p>&nbsp;</o:p></span></b></p>
<p class="MsoNormal">Query :- <o:p></o:p></p>
<p class="MsoNormal">======<br>
- We would like to know what is the reason for advancing the scrambler in packet mode?<o:p></o:p></p>
<p class="MsoNormal"><o:p>&nbsp;</o:p></p>
<p class="MsoNormal">Let us know our understanding is correct or not? <o:p></o:p></p>
<p class="MsoNormal"><o:p>&nbsp;</o:p></p>
<p class="MsoNormal">Kind Regards<o:p></o:p></p>
<p class="MsoNormal">Lana<o:p></o:p></p>
<p class="MsoNormal"><o:p>&nbsp;</o:p></p>
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