Re: [Fwd: Crc-32c example in iSCSI spec]

[Steve Blightman <steve@alacritech.com>]

I believe the examples for the ISCSI CRC  have the wrong endianness.

As yiou suugested over the phone I ran some Ethernet frames through a
simulation. I have some difficulty running the exact simulations you
wanted becuase the minimum size Ethernet frame is 64 bytes.

However using the Ethernet CRC polynomial,
Running 64 bytes of 0 onto the wire, we append "36 63 8d 75" onto the
wire for the CRC - "36" goes out first.
Running 64 bytes of all 1, we append "ba 87 61 0f" onto the wire - "ba"
goes out first.

Using the same logic for the ISCSI polynomial
Running 64 bytes of 0 I think we should append "67 eb c8 03" - "67"
going out first
and running 64 bytes of all 1 we should append "66 4e cd 2f" - "66"
going out first

And now for 32 bytes with the ISCSI polynomial

Running 32 bytes of 0 we should append "aa 36 91 8a" - "aa" going out
first
Running 32 bytes of all 1 we should append "43 ab a8 62" - "43" going
out first

I don't want to get into an endless endian debate, but I believe it is
important to get the order of these bytes in the right order, so that we
can use the same hardware to check as well as to generate CRCs.

Thanks for your help on this,
Steve Blightman