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

[Tom Herbert <[e-mail]>]

On Mon, Jul 19, 2021, 2:32 PM Joseph Touch <[e-mail]> wrote:

> Hi, Tom,
>
> First, there’s a good reason to not assume we can put the fragment “whole
> packet” options in the first fragment: size. We currently have no limit on
> how much space options can use in general. Per-fragment options clearly
> need to fit inside the fragment with fragment data. But the options on the
> reassembled packet might be difficult to assume can be contained in the
> first fragment alone.
>
> Further, you have proposed several scenarios that claim that users may
> either want or need to not support legacy mode UDP options, but do want to
> use fragment-based options. That’s not permitted in the current spec and
> never has been.
>
> Mode is chosen by the transmitter, not the receiver. Support for legacy
> mode has always been required.
>

That limits the usability and hence adoption of the protocol.


> Further, putting a functionality limit (either in length or support for
> legacy mode) to enhance the performance of some implementations doesn’t
> seem prudent.


> Joe