SAS-2: A question on SSP Link Layer Protocol

Day, Brian Brian.Day at lsil.com
Fri Sep 8 14:16:36 PDT 2006


* From the T10 Reflector (t10 at t10.org), posted by:
* "Day, Brian" <Brian.Day at lsil.com>
*
Steve...
That would happen during non-interlocked DATA frames.  For example, the
link could receive 2 DATA frames back-to-back before any ACK/NAKs are
ever transmitted.
That should never happen when receiving interlocked frames though...
which is what the transport layer is checking for in section 9.2.6.2.2.3
in the ST_IFR state.
Brian Day
LSI Logic
-----Original Message-----
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Stephen
FINCH
Sent: Friday, September 08, 2006 9:54 AM
To: T10 Reflector
Subject: SAS-2: A question on SSP Link Layer Protocol
* From the T10 Reflector (t10 at t10.org), posted by:
* Stephen FINCH <steve.finch at st.com>
*
In section 7.16.8.7 SSP_RF (receive frame control) state machine, in the
last paragraph and its bullet items it states:
"
	A) if the last Rx Balance Status message received had an
argument of Balanced, send a Frame Received (ACK/NAK Balanced)
confirmation to the port layer; or
	B) if the last Rx Balance Status message received had an
argument of Not Balanced, send a Frame Received (ACK/NAK Not Balanced)
confirmation to the port layer.
"
Since ACKs and NAKs can be sent at any where within an SSP connection
including within a frame being transmitted, can anyone provide an
example of when case B will ever occur?  I.e., after receiving a frame
the ACK or NAK of the previous frame has not been sent?
Am I missing something?
Steve Finch
STMicroelectronics
303 381-3587
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