Re: effect of initializing CRC reg to 1's depends on implementati on? iSCSI

[Luben Tuikov <ltuikov@yahoo.com>]

--- Mark Bakke <mbakke@cisco.com> wrote:
> This is becoming somewhat disturbing, given the comment
> about
> the Ethernet CRC.

Which comment did you have in mind?

>  The intent of the document is
> absolutely,
> positively to keep the CRC identical to Ethernet, with
> the
> exception of the generator, just as Paul had said.

Then we should JUST say THAT in the iSCSI spec.
I think that it is enough.

> If someone has an
> implementation
> that does not match the examples, they simply try a few
> variations until they get it right.

Mark, iSCSI draft/rfc is supposed to be THE AUTHORITY
reference for iSCSI implementation.

You cannot say ``just try a few variations until you get it
right''!

>  This has worked very
> well
> for everyone I have talked to who is implementing the
> CRC.

The reason is that they know and/or have a preconception
about what is being talked about. I.e. the current
description is very IMPLICIT. As part of a definition
document it has to be EXPLICIT.

You need an outsider, an impartial party to scrutinize the
draft. All parts of it.
 
> Here is some text that I had suggested adding instead of
> (or 
> in addition to) the mathematical description a while ago:

I liked the one you had above better.
 
> The above, plus the examples, have seem to work out just
> fine
> for the implementors.  Getting the math right would be
> nice, but
> most of us implementors don't look at it anyway, and
> prefer the
> more practical description.  If we are going to include
> the math,
> it has to match the examples.

Most certainly agree! Including math is not necessary. We
can prepare a document (what I and Vince are doing) and
make a reference to it in the draft for all the math,
optimization, derivation, equivalence and implementaion
details.
 
> Anyway, my guess is that is what you are discussing; it
> was just
> disturbing to think that anything but the Ethernet + new
> poly
> was being considered, since that has been agreed on for a
> long
> time, and is being widely implemented.

... and not being mentioned anywhere in the draft!

-l




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