Re: [tsvwg] UDP options and header-data split (zero copy)

["C. M. Heard" <[e-mail]>]

On Sun, Aug 1, 2021 at 2:56 PM Joe Touch wrote:
> > On Aug 1, 2021, at 2:33 PM, Joseph Touch wrote:
> > > > On Sun, Aug 1, 2021 at 10:48 AM Joseph Touch wrote:
> > > > Also, the trailing variant allows per-reassembled options
> > > > to be arbitrarily long (limited by the reassembled length),
> > > > rather than requiring them to fit inside a single fragment.
> > >
> > >
> > > If that is the intent, then
> > > draft-ietf-tsvwg-udp-options-13#section-5.5 needs significant
clarification.
> >
> > Yes; this is pending.
>
> Fwiw I was assuming that field pointed to the start of the trailer
> options measured from the start of the UDP data (I might have [forgotten]
> that nuance in the -13 text) If that field points inside this
> fragment, it can help the split. If not, then the per reassembled
> options could be split out only after reassembly. But they don’t need
> to fit in a single fragment.

I have to say that I was not altogether pleased with what I thought the
draft said, but I find this level of complexity to be downright
alarming, and I don't see a need for it. It's reminiscent of IPv6
fragmentation, which has stubbornly resisted correct specification (witness
the verified errata posted against RFC 8200). UDP fragmentation is
important to have largely because IP fragmentation, and IPv6 fragmentation
in particular, have not been fully successful. Let's please not repeat
those mistakes. Keep it simple, please.

Mike Heard