RE: iSCSI CRC: A CRC-checking example

[Black_David@emc.com]

From a practical standpoint, using the same implementation framework
(for lack of a better word) as Ethernet reduces the opportunity
to get this wrong - a designer who's done an Ethernet CRC does
the same thing with the new CRC polynomial and the result works.

If this aspect of CRC usage "ain't broke", I would think
that "don't fix it" is the preferred course of action ;-).

Thanks,
--David

> -----Original Message-----
> From: Douglas Otis [mailto:dotis@sanlight.net]
> Sent: Thursday, August 23, 2001 5:43 PM
> To: Sanjay Goyal; 'CAVANNA,VICENTE V (A-Roseville,ex1)'
> Cc: ips@ece.cmu.edu
> Subject: RE: iSCSI CRC: A CRC-checking example
> 
> 
> Sanjay,
> 
> In short, the reflected table is likely to require fewer instructions to
> implement a lookup than a non-reflected table.  Secondly, if the processor
> is Little Endian, then the result is already in network order without byte
> swapping.  Obviously this last point only helps if you are using a Little
> Endian processor but this happens only once per packet whereas the lookup
> may happen every byte.  Third, the inverted store improves the sensitivity
> to the packet length.  All these Ethernet techniques seems to be good
> things.  One difference however is the polynomial.
> 
> Doug
> 
> > The last line says
> >  "but I suppose it is advantageous to do things the ethernet way."
> > May I know in what ways it would be advantageous.
> >
> > Regards
> > Sanjay Goyal
> >