Subject: Re: iSCSI padding should be 0

From: Julian_Satran/Haifa/IBM%IBMIL <[email-masked]>
Date: Fri, 27 Jul 2001 18:45:59 +0300

Perhaps we should say MUST be sent as 0 and keep quiet about what the
receiver should  do (check for 0 - we don't want that).

Thanks,Julo

"Eddy Quicksall" <[email-masked]> on 27-07-2001 18:18:33

Please respond to [email-masked]

To:   Julian Satran/Haifa/IBM@IBMIL, [email-masked]
cc:
Subject:  iSCSI padding should be 0

Julian,

Section 2.1 says the padding should be 0. I guess that is correct because
one may not use CRC and therefore may not want to set them to 0. Wouldn't
it
be better if section 2.1 was more specific and mentioned when they must be
0
if there is a CRC. Also, I noticed at the UNH plug fest that at least one
person thought "should" meant "must". Therefore, I don't think it should
say
"should" ... I think it should not mention the 0'ness unless there is a CRC
present.

Also,

        transmission.  Padding bytes, when presents in a segment covered by
a
        CRC, have to be set to 0 and are included in the CRC.

should say "when present in".

[email-masked]

---

From: "Eddy Quicksall" <[email-masked]>
Date: Fri, 27 Jul 2001 15:05:59 -0400

I saw one objection to this by Michael Fischer
[[email-masked]]. He pointed out that if there is no CRC then
why require the padding to be 0. I agree with his point.

The problem is with software only implementations ... if they use the
sockets send function and if they are sending from a ULP buffer and if the
data being sent needs padding, they will have to either copy to another
buffer or do an extra tiny send for the pad.

So, my thinking is that we say:

    iSCSI PDUs are padded to an integer number of 4 byte words. If CRC is
being used, the padding MUST be 0. If CRC is not being used, the content of
the padding is unpredictable and irrelevent.

What do you think?

Eddy