Re: [tsvwg] New Version Notification for draft-herbert-udp-space-hdr-01.txt

[Tom Herbert <[e-mail]>]

On Wed, Jul 10, 2019, 9:49 AM Joe Touch <[e-mail]> wrote:

> a) I gave a very specific pair of reasons. To repeat, in detail:
>
> - UDP options already provides the same vehicle (type flags) for others to
> use the space
>
- UDP options are not limited in length and (now) already consume the
> entirety of that space when used
>
> b) it is a waste of time to even provide further reasons.
>
> It would be much more useful IMO for others to comment on the other
> pending suggestions.
>
> (so others can feel free to skip the rest of this post)
>
>
> But since you asked:
>
> - the length field unnecessarily limits use of the space to chunks of 1020
> bytes
>
> - the front padding isn't helpful (the checksum can be adjusted with a
> byte-swap if not half-word aligned)
>
> - the length field assumes (incorrectly) that all use of the space is in
> chunks that end at word boundaries
>
> - the excessive space for experiments is not needed, given RFC6994
> techniques
>
> - it wastes space and provides no additional capability for the current
> UDP option approach
>
> But most importantly:
>
> - there are no currently known uses of the surplus space
>
> - but even if there were, they would need to be adapted to this scheme
> (and could instead be adapted to the existing UDP options)
>
>
> Again, this serves no useful purpose and is actually wasteful.
>

The UDP surplus header provides alignment, integrity check, disambiguation
for other uses of surplus space, a means to extend the UDP header,
friendliness with HW and SW implentations, extensibility, uniformity with
the other notable transport protocol that contains options, addresses the
requirements for UDPv6 checksum without having to invoke RFC6939. Overhead
is four bytes (seven with worse case padding) which is insignificant
compared to the benefits.

Joe
>
>
> On 2019-07-10 09:18, Tom Herbert wrote:
>
>
>
> On Wed, Jul 10, 2019, 7:51 AM Joe Touch <[e-mail]> wrote:
>
>> This approach serves absolutely no useful purpose.
>
>
> Obviously, I disagree with that assessment. See the motivations section in
> the draft.
>
>
>>
>> The UDP options already provide a vehicle for others to use the surplus
>> space and it already consumes the entirety of that space.
>>
>> I hope those in the WG interested in improving UDP options will comment
>> on the other posted issues instead.
>
>
> Well, I've already posted many comments on that UDP options proposal, I
> would hope my proposal gets equally constructive feedback from the WG (more
> than just an arbitrary statement that it has no useful purpose).
>
> Tom
>
>
>
>
>>
>> Joe
>>
>> > On Jul 8, 2019, at 4:52 PM, Tom Herbert <[e-mail]> wrote:
>> >
>> > Hello,
>> >
>> > I've posted a new draft version for the UDP surplus space header. The
>> > version provides detail on the use cases of the UDP Surplus Header as
>> > a protocol trailer and protocol header. Also, I added a motivations
>> > section and added appendices for implementation considerations.
>> >
>> > Thanks,
>> > Tom
>> >
>> > ---------- Forwarded message ---------
>> > From: <[e-mail]>
>> > Date: Mon, Jul 8, 2019 at 4:48 PM
>> > Subject: New Version Notification for draft-herbert-udp-space-hdr-01.txt
>> > To: Tom Herbert <[e-mail]>
>> >
>> >
>> >
>> > A new version of I-D, draft-herbert-udp-space-hdr-01.txt
>> > has been successfully submitted by Tom Herbert and posted to the
>> > IETF repository.
>> >
>> > Name:           draft-herbert-udp-space-hdr
>> > Revision:       01
>> > Title:          UDP Surplus Header
>> > Document date:  2019-07-08
>> > Group:          Individual Submission
>> > Pages:          16
>> > URL:
>> > https://www.ietf.org/internet-drafts/draft-herbert-udp-space-hdr-01.txt
>> > Status:
>> https://datatracker.ietf.org/doc/draft-herbert-udp-space-hdr/
>> > Htmlized:
>> https://tools.ietf.org/html/draft-herbert-udp-space-hdr-01
>> > Htmlized:
>> > https://datatracker..ietf.org/doc/html/draft-herbert-udp-space-hdr
>> <https://datatracker.ietf.org/doc/html/draft-herbert-udp-space-hdr>
>> > Diff:
>> https://www.ietf.org/rfcdiff?url2=draft-herbert-udp-space-hdr-01
>> >
>> > Abstract:
>> >   This specification defines the UDP Surplus Header that is an
>> >   extensible and generic format applied to the UDP surplus space. The
>> >   UDP surplus space comprises the bytes between the end of the UDP
>> >   datagram, as indicated by the UDP Length field, and the end of the IP
>> >   packet, as indicated by IP packet or payload length. The UDP Surplus
>> >   Header can be either a protocol trailer of the UDP datagram, or a
>> >   protocol header which effectively serves as an extended UDP header.
>> >
>> >
>> >
>> >
>> > Please note that it may take a couple of minutes from the time of
>> submission
>> > until the htmlized version and diff are available at tools.ietf..org
>> <http://tools.ietf.org>.
>> >
>> > The IETF Secretariat
>> >
>>
>>