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

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

On Thu, Jul 15, 2021 at 2:51 PM Tom Herbert wrote:
> On Thu, Jul 15, 2021 at 2:32 PM Joseph Touch wrote:
> > And there is no way to avoid trailers for non-fragmented packets.
> >
> Right trailers are only needed in that case. In the case of fragment
> using both headers and trailers simultaneously is unnecessary
> complexity that provides no benefit. If just headers are used then the
> system doesn't need to support trailers for that case and header-data
> split continues to work as expected.

On Fri, Jul 16, 2021 at 12:12 AM Paul Vixie replied:
> +1.

Let me add my voice to this. The specification of FRAG in -13 is
unnecessarily complex. We do not need both headers (for per-frag
options) and trailers (for per-datagram options). That format, as
Tom correctly notes, is an impediment to checksum offload for
encapsulated protocols. The generality of allowing any option to
be encoded as per-datagram or per-fragment is a level of flexibility
that is comparable to the flexibility offered by independently
steerable front wheels: it is neither necessary nor safe, as very
few options can serve in both capacities, and there are other ways to
deal with those.

Mike Heard