Re: [tsvwg] RDMA Support by UDP FRAG Option

[Joseph Touch <[e-mail]>]

> On Jun 21, 2021, at 3:29 PM, C. M. Heard <[e-mail]> wrote:
> 
> On Mon, Jun 21, 2021 at 3:20 PM Joseph Touch wrote:
>> It's true that OCS is optional when UDP CS==0, but my understanding is that per the current spec, if it is present, the receiver is required to check it and drop the options if it does not follow the rule specified for OCS.
> 
> Yes, and that makes sense - if you’ve added OCS, regardless of whether the UDP CS==0 or not, then you want the options checked. All we currently have been saying is that “OCS can be omitted when CS==0”, not that it MUST be.
> 
>> And that rule is not that the surplus area sums to zero, but that the surplus area plus the pseudo-header consisting of the surplus are length sums to zero.
> 
> It was originally (through draft-ietf-tsvwg-udp-options-05)  to cover the surplus area only; it was in the additional CCO-like behavior that it changed to add the pseudo header  (the surplus length). So are we going back to the pre-CCO definition?
> 
> I'm certainly not advocating for that! Tom Hernert seems to want that, but I sure don't, and as I indicated in my reply to him, I think that going back to the pre-CCO definition would undermine the chances of successful deployment.

OK. I thought I saw something in your response that indicated either that we needed to adjust the calculation or that we need to force it being ignored when UDP CS==0.

Joe