Re: [tsvwg] I-D Action: draft-ietf-tsvwg-udp-options-dplpmtud-09.txt

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

On Sun, Jul 2, 2023 at 1:50 PM PDT, in the thread entitled "Remaining
issues for draft-ietf-tsvwg-udp-options-22," Gorry Fairhurst wrote:
> UDP Options itself doesn't generate the response, it passes the REQ
> upwards to the protocol that does and that sends the RES option.

However, Section 3 of  draft-ietf-tsvwg-udp-options-dplpmtud-09 says:

   When DPLPMTUD is within the UDP transport service, the UDP Options
   processing is responsible for sending probe packets to determine a
   PLPMTU, as described in this document.

It might be better to say "the DPLPMTUD State Machine" rather than "the
UDP Options processing" to make it clear that it is the shim above UDP
Options Transport in the figure that does this, and not UDP Options
itself. This would help to emphasize the point that UDP Options on its
own does not generate responses to any option.

The document does not describe in detail what happens when an Upper
Layer Protocol (or application) implements DLPMTUD using UDP options.
For me. it's easy enough to infer that the DPLPMTUD State Machine has to
reside within the application, and that the application must initiate
the actions to generate probe packets and responses. However, a sentence
making that point explicit would not hurt.

Thanks and regards,

Mike Heard

On Thu, Jun 29, 2023 at 10:08 AM <[e-mail]> wrote:
>
>
> A New Internet-Draft is available from the on-line Internet-Drafts
> directories. This Internet-Draft is a work item of the Transport Area Working
> Group (TSVWG) WG of the IETF.
>
>    Title           : Datagram PLPMTUD for UDP Options
>    Authors         : Godred Fairhurst
>                      Tom Jones
>    Filename        : draft-ietf-tsvwg-udp-options-dplpmtud-09.txt
>    Pages           : 17
>    Date            : 2023-06-29
>
> Abstract:
>    This document specifies how a UDP Options sender implements Datagram
>    Packetization Layer Path Maximum Transmission Unit Discovery
>    (DPLPMTUD) as a robust method for Path Maximum Transmission Unit
>    discovery.  This method uses the UDP Options packetization layer.  It
>    allows an application to discover the largest size of datagram that
>    can be sent across the network path.  It also provides a way to allow
>    the application to periodically verify the current maximum packet
>    size supported by a path and to update this when required.
>
> The IETF datatracker status page for this Internet-Draft is:
> https://datatracker.ietf.org/doc/draft-ietf-tsvwg-udp-options-dplpmtud/
>
> There is also an htmlized version available at:
> https://datatracker.ietf.org/doc/html/draft-ietf-tsvwg-udp-options-dplpmtud-09
>
> A diff from the previous version is available at:
> https://author-tools.ietf.org/iddiff?url2=draft-ietf-tsvwg-udp-options-dplpmtud-09
>
> Internet-Drafts are also available by rsync at rsync.ietf.org::internet-drafts
>