[e2e] Re: [Tsvwg] Really End-to-end or CRC vs everything else?

Jonathan Stone jonathan at DSG.Stanford.EDU
Thu May 24 21:31:43 PDT 2001

not wanting to get sucked into this either, but:

>The application endpoints thus have an extremely high degree of certainty 
>that data is not corrupted between the checksum creation and decoding if 
>done at SCTP level, as long as the checksum is indeed done at the end-point 
>machines (big requirement in protocol definition, lest someone try to do it 
>down in some NIC).

As best i follow it, doing checksums "down in some nic" is exactly
what the iscsi group (and less so sctp) are proposing.

>crc32 is thought to be better at detecting errors than the alternative, and 
>can be computed at speeds that closely match traditional addition-based 
>checksums.  So in designing a new protocol, I'd lean towards crc32.

But *why* is crc32 thought to be better than a 32-bit mod-2^32
checksum or a fletcher checksum with two 16-bit halves?
A citation would be wonderful.

[... md5 as an error-check function to defeat would-be middleboxers...]

If you put that in the transport layer, won't that makes communication
without a shared-secret impossible? At least without using some other
transport protocol, to bootstrap a D-H or SPEKE or other initial key exchange.

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