SAS - ACK Vs. NAK and frame errors

[Sriram Srinivasan]

* From the T10 Reflector (t10 at t10.org), posted by:
* Sriram Srinivasan <srirams at lsil.com>
*
In 02-157r0 (SAS proposed working draft) ...

7.13.2 states 

"ACK means the frame was received into a frame buffer without errors.  NAK 
means the frame was received with an error (eg a CRC error).  There are 
several versions of NAK indicating the specific cause for rejection.  
NAK(CRC ERROR) indicates the frame was received, but the CRC check failed.  
NAK(GENERAL ERROR) indicates that some other type of error occurred"

The draft should specify what "received into a frame without errors" means? 
i.e. explicitly state the errors that can happen.  Something explicit like 
"ACK always if CRC check passes" would be good and all the other checks on 
the fields in the frame header and frame IU can live in the transport layer 
which result in a CHECK CONDITION status if the checks fail ... of course 
there is, apparently, a debate on the hashed device names checks withholding 
the ACKs ... with the exception of these (at least for now), 7.13.2 should 
specify what checks are handled in the link before we ACK/NAK a frame and 
should avoid nebulous definitions like "some other type of error occurred" 
:)

thanx,
\Sriram\




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	"FORGET NOT THAT THE EARTH DELIGHTS TO FEEL YOUR BARE FEET,
               AND THE WINDS LONG TO PLAY WITH YOUR HAIR"
                                          -Khalil Gibran

 Sriram Srinivasan                       Sriram.Srinivasan at lsil.com
 ASIC Design Engineer, LSI Logic,
 2001 Danfield Ct., 				Phone: 970-206-5847
 Fort Collins, CO 80525				FAX  : 970-206-5244
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