Re: iscsi: header digest issue

[Paul Koning <ni1d@arrl.net>]

Excerpt of message (sent 2 March 2002) by Julian Satran:
> the logit is bit more trickier - with 1 bit distance you will get to a 
> WRONG CRC - Julo

I don't see why that it so.  

If a bit error changes AHSLength from 0 to 2, the receiver will take
the header that was sent -- with its digest -- and process that PLUS
the next 8 bytes after the header through its CRC (because it thinks
the header is 8 bytes longer than what the sender intended).  That's a
64 bit error burst.  CRC-32 has the property that it will fail to
detect a 64 bit burst with probability roughly 2^-32.

Therefore, not all 1-bit errors will be detected.

I don't see what tricky logic can get you around this case, but if you
know of some, could you say what it is?

     paul