Re: [tsvwg] draft-tuexen-tsvwg-sctp-zero-checksum-02 adoption

[Nils Ohlmeier <[e-mail]>]

> On Apr 12, 2023, at 06:20, [e-mail] wrote:
> 
>> On 11. Apr 2023, at 19:15, Nils Ohlmeier <[e-mail]> wrote:
>> 
>> Hello,
>> 
>> I’m supporting adoption of draft draft-tuexen-tsvwg-sctp-zero-checksum-02, because it is going to be useful for all WebRTC endpoints out there to have the option to skip the checksum step.
>> 
>> I also reviewed the draft. The only concern I found is this sentence:
>> 
>> "Since the lower layer of SCTP can not be IPv4 or IPv6 as specified in [RFC9260] or UDP as specified in [RFC6951], no problems with middle boxes expecting correct CRC32c checksums in the SCTP packets are expected.”
>> 
>> Which confuses me, because it sounds to me like this is trying to say that SCTP over IPv4 or IPv6 can not be done. Which obviously doesn’t make any sense. But I honestly fail to parse what this sentence is suppose to tell me (besides no problems with middle boxes is expected).
> Would using
> 
> One example of such a lower layer is the use of SCTP over DTLS as
> described in [RFC8261] (as used in the WebRTC context). Counter
> examples include:
> 
> * SCTP over IPv4 or IPv6 as specified in [RFC9260].
> 
> * SCTP over UDP as specified in [RFC6951].
> 
> * The use of SCTP Authentication as specified in [RFC4895].
> 
> Therefore using an incorrect zero checksum will not result in
> problems with middle boxes expecting correct CRC32c checksums in SCTP
> packets.
> 
> be clearer?

Yes I think that helps.
I think if you expand the last sentence in our proposal to something like:

Therefore using an incorrect zero checksum when using SCTP over DTLS will not result in
problems with the middle boxes expecting correct CRC32c checksums in SCTP packets.

Should remove any remaining ambiguity.

Best
  Nils