SAS SSP link layer - which NAK for frame size errors

Bill Galloway BillG at breatech.com
Tue Jun 11 07:43:46 PDT 2002


* From the T10 Reflector (t10 at t10.org), posted by:
* "Bill Galloway" <BillG at breatech.com>
*
That is what I remembered too.

Bill Galloway
BREA Technologies, Inc.
P: (281) 530-3063
F: (281) 988-0358
BillG at breatech.com 

-----Original Message-----
From: Evans, Mark [mailto:Mark_Evans at maxtor.com] 
Sent: Tuesday, June 11, 2002 9:31 AM
To: 'BillG at breatech.com'; t10 at t10.org
Subject: RE: SAS SSP link layer - which NAK for frame size errors


HI Bill,

I thought we came to the conclusions in Minneapolis that the only thing
that should cause a NAK on an SSP frame was a CRC error, and that all
other checking of the frame would be done at the transport layer.  Did I
miss something?

Regards,

Mark Evans
Maxtor Corporation

 -----Original Message-----
From: 	Bill Galloway [mailto:BillG at breatech.com] 
Sent:	Tuesday, June 11, 2002 6:52 AM
To:	t10 at t10.org
Subject:	RE: SAS SSP link layer - which NAK for frame size errors

* From the T10 Reflector (t10 at t10.org), posted by:
* "Bill Galloway" <BillG at breatech.com>
*
I do not believe that the SSP link layer should NAK an illegal
(malformed) frame.  It should only be responsible for ACK/NAK on
something that looks like a real frame (i.e. SOF reasonable byte count
EOF).

Bill Galloway
BREA Technologies, Inc.
P: (281) 530-3063
F: (281) 988-0358
BillG at breatech.com 

-----Original Message-----
From: owner-t10 at t10.org [mailto:owner-t10 at t10.org] On Behalf Of Elliott,
Robert (Server Storage)
Sent: Monday, June 10, 2002 5:18 PM
To: t10 at t10.org
Subject: SAS SSP link layer - which NAK for frame size errors


* From the T10 Reflector (t10 at t10.org), posted by:
* "Elliott, Robert (Server Storage)" <Elliott at hp.com>
*
Which NAK should the link layer return if it detects a frame size that
is out of bounds?

There are currently two NAK primitives:
NAK(GENERAL ERROR)
NAK(CRC ERROR)

Options:
1. Use NAK(GENERAL ERROR) to report both too-small and too-large frames
2. Add NAK(FRAME SIZE ERROR) and use it for both cases 3. Add NAK(FRAME
SIZE TOO SMALL) and NAK(FRAME SIZE TOO LARGE) 4. Rename NAK(GENERAL
ERROR) to NAK(FRAME SIZE ERROR) and use it for both cases 5. Add
NAK(FRAME SIZE TOO SMALL) and NAK(FRAME SIZE TOO LARGE) and remove
NAK(GENERAL ERROR)

[if the link layer doesn't enforce any minimum frame size, only the
too-large case need be handled]

The group's conclusion will need to be included in the SSP link layer's
SSP_TAN and SSP_RF state machines.

--
Rob Elliott, elliott at hp.com
Industry Standard Server Storage Advanced Technology Hewlett-Packard

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