[Int-area] Re: [tsvwg] Re: UDP options [was IP Parce ls and Advanced Jumbos (AJs)]

Hi Gorry, a point of clarification is that IP parcels and AJs are not necessarily only about huge payloads.
It is true that an IP parcel can be as large as 2**24 and an AJ can be as large as 2**32, but a minimal
IP parcel is one with a single segment of 1-octet in length and a minimal AJ is one with a NULL payload.
All sizes in between (ranging from very small to very large) are possible, and there is no longer anything
special about 64KB.

Fred

> -----Original Message-----
> From: Gorry Fairhurst <[email protected]>
> Sent: Wednesday, November 20, 2024 12:06 AM
> To: [email protected]; C. M. Heard <[email protected]>; [email protected]
> Cc: int-area <[email protected]>; 6man <[email protected]>; TSVWG <[email protected]>
> Subject: Re: [tsvwg] Re: UDP options [was IP Parcels and Advanced Jumbos (AJs)]
> 
> On 19/11/2024 23:58, [email protected] wrote:
> > These proposed changes to UDP are thoughtprovoking.
> >
> > When UDP-Lite (RFC3828) was proposed, it was eventually shunted to its own IP protocol number, rather than risk messing up existing UDP
> implementations and semantics for even a very minor change. I gather that move to a different port was done very late in the process.
> >
> > The changes proposes in UDP options and in parcelling seem much much larger. Surely they should be treated as UDP-Lite was, and as UDP-
> alike but not as UDP, and given their own IP protocol number?
> >
> > thanks
> >
> >
> > Lloyd Wood
> > [email protected]
> 
> I think Lloyd this set of therads is conflating two things:
> 
> UDP Options has been developed over many years as a specification, and
> (at least in tsvwg) is thought complete - we have evidence the method
> works across existing networks and the WG has analysed whether we can
> extend it safely. It's been through WGLC and should hopefully complete
> AD review soon. It's an addition to UDP.
> 
> IP parcels has been presented at the IETF, but as far as I know, hasn't
> yet been adopted. I don't expect this to be ready for quite some time,
> especially since it anticipates new devices on-path that have been
> optimised for very large packets.  In most parts of the network, we are
> still struggling to support near 1500B. If packets are > 64 KB as
> imagined, there will be many more conbsiderations, not least how
> fragmentation is handled within the network and the relationship to loss
> recovery, congestion control, etc. If the IETF decides this is an
> important use-case, I see this as further out, with many things to decide.
> 
> Best wishes,
> 
> Gorry
> 
> 
> >
> >
> >
> >
> >
> > On Wednesday 20 November 2024 at 05:12:00 GMT+11, [email protected] <[email protected]> wrote:
> >
> >
> >
> >
> >
> > Hi, all,
> >
> > I have not investigated this issue. Any new UDP option proposal would need to be evaluated in detail AND would need to follow the design
> requirements in the UDP options doc.
> >
> > Further, I would urge any option that is per-IP packet to be an IP option; UDP options are intended for user endpoints, not the (existing)
> protocol subsystem per se. I don’t yet understand whether the proposed parcel parameters should be an IP option or UDP option, but UDP
> options are NOT intended as a place you can put info that you don’t want to or can’t put in IP options per se. IP options are per IP packet; UDP
> options are per UDP message. We’d need to understand why parcels are fiddling with UDP option space - which may already be used by the
> UDP endpoints.
> >
> > Joe
> >
> >
> > —
> > Dr. Joe Touch, temporal epistemologist
> > www.strayalpha.com
> >
> >
> >> On Nov 14, 2024, at 4:54 PM, C. M. Heard <[email protected]> wrote:
> >>
> >> Fred and WG participants,
> >>
> >> I have finally freed up some cycles to read draft-templin-6man-parcels2-14, and I have found some issues with it that need to be
> addressed with respect to its handling of UDP.
> >>
> >> The big one -- if I have correctly understood what I have read -- is that it's possible for a single parcel of a parcellated UDP packet to be
> turned into a stand-alone UDP packet (see Section 7.1) and delivered to an end system as such (see Section 7.4). That packet would contain
> a Parcel Parameters UDP Option to tell the endpoint host that the packet is a parcel and not a complete UDP datagram, but the option kind is
> taken from the SAFE option space (KIND = 127; see draft-ietf-tsvwg-udp-options#section-10). Legacy endpoints that do not understand UDP
> options will ignore that SAFE option and will deliver the parcel as if it were a complete UDP datagram. That, to my mind, is completely
> unacceptable. Unlike TCP, which is a byte-stream protocol in which segment boundaries have no meaning for the upper layer, UDP is a
> datagram protocol in which message boundaries are meaningful to the upper layer. The protocol has a contract with the upper layer to deliver
> a message as it was submitted or not at all. Delivering a parcel in a manner that can be misinterpreted as a complete datagram violates that
> contract.
> >>
> >> It is possible to repair this defect by making the Parcel Parameters Option, or something with equivalent functionality, into an UNSAFE
> option. My suggestion would be to define an UNSAFE version of the existing FRAG option (see draft-ietf-tsvwg-udp-options#section-11.4) --
> let's call it UFRAG -- that would allow for packet sizes greater than 65,535 bytes. The same option could be used to send singleton advanced
> jumbo packets as atomic fragments. This would avoid any need to modify the base UDP and UDP Options specifications.
> >>
> >> Additionally: during the review of draft-ietf-tsvwg-udp-options, Joe Touch correctly pointed out that RFC 2765 (and its predecessor RFC
> 2147) failed to note that it updated RFC 768. Similar concerns apply to TCP. If this draft foes forward, it should note that it updates the UDP
> and TCP specifications, and it should get buy-in from TSVWG and TCPM.
> >>
> >> Thanks and regards,
> >>
> >> Mike Heard
> >>
> >>
> >>
> >>
> >>
> >> On Sun, Sep 29, 2024 at 3:51 PM C. M. Heard <[email protected]> wrote:
> >>> Fred,
> >>>
> >>> I currently hold the editing pen for the changes to the UDP Options draft that have been requested prior to the shepherd report, and my
> intention is to remain silent about how, if at all, IP Parcels and Advanced Jumbos (AJs) will support UDP Options.
> >>>
> >>> I'll provide comments on the IP Parcels and Advanced Jumbos work at a later date, when I have spare intellectual cycles to fully
> comprehend the contents of draft-templin-6man-parcels2. At this point I must confess that, like Brian, I do not understand how a receiver will
> locate the options trailer in the case of an IP Payload Length exceeding 65535. Like Joe, I think it would be better to put the options just after
> the UDP header and make a new UNSAFE option to delimit the position where the options end and the user data begins.. But that discussion
> (and the corresponding update to the UDP options draft) can occur when it is ripe; IMO that is not the case at this time.
> >>>
> >>> Respectfully,
> >>>
> >>> Mike Heard
> >>>
> >>> On Sun, Sep 29, 2024 at 3:07 PM Templin (US), Fred L <[email protected]> wrote:
> >>>>
> >>>>
> >>>> IP parcels and Advanced Jumbos (AJs) of all sizes ranging from 1 to 2^32 are now eligible
> >>>> for using UDP options. This is just one way in which they offer a better service than RFC2675
> >>>> Jumbograms, but there are also many others.
> >>>>
> >>>> Joe, you can either note this in your draft or just leave it be and let my draft do an
> >>>> “updates UDP options”.
> >>>>
> >>>> Thank you - Fred
> >>>>
> >>>>
> >>>>
> >>>>
> >>>> From: Brian Carpenter <[email protected]>
> >>>> Sent: Saturday, September 28, 2024 2:20 AM
> >>>> To: Gorry (erg) <[email protected]>
> >>>> Cc: Joe Touch <[email protected]>; Templin (US), Fred L <[email protected]>; Tim Chown <[email protected]>;
> Internet Area <[email protected]>; IPv6 List <[email protected]>; tsvwg IETF list <[email protected]>
> >>>> Subject: [EXTERNAL] Re: [tsvwg] Re: UDP options [was IP Parcels and Advanced Jumbos (AJs)]
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>    EXT email: be mindful of links/attachments.
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>> That works for me..
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>> (via tiny screen & keyboard)Regards,        Brian Carpenter
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>
> >>>> On Sat, 28 Sept 2024, 19:08 Gorry (erg), <[email protected]> wrote:
> >>>>
> >>>>
> >>>>> See below> On 28 Sep 2024, at 04:05, Brian E Carpenter <[email protected]> wrote:> > Joe,> On 28-Sep-24 03:13,
> [email protected] wrote:>>>> On Sep 27, 2024, at 7:58 AM, Templin (US), Fred L <[email protected]>
> wrote:>>> >>>> Indeed. But if sendmsg() and recvmsg() can and do generate RFC2675 packets, it means that any discussion of obsoleting
> RFC2675 should be>>>> off the table.>>> >>> No one that I know of has suggested obsoleting RFC2675 - my documents do not say
> "obsoletes" (nor even "updates”).>> That approach to UDP jumbo grams is incompatible with UDP options.>> And yes, there was a proposal to
> move that RFC to historic:>> Jones, T., G. Fairhurst, "Change Status of RFC 2675 to Historic," draft-jones-6man-historic-rfc2675, May 2019.>>
> We COULD have a new option with a longer length, but that’s not in our baseline draft.> > Wouldn't that be tricky, because the options follow
> the whole payload as I understand it? So a JumboUDPgram has to be received in full, however big it is, before the option saying that it's a
> jumbo can be received and interpreted.> > Where the udp-options draft says:> >>> The technique has been proposed for deprecation [Jo19].>
> > I think you'd better change it to something like:> > The technique is known to be in active use in special situations, so cannot reasonably be
> deprecated. However, users of this technique cannot simultaneously use UDP options.> >    Brian> I do not think the I-D needs to say anything
> about the deployment status of jumbograms, that another topic.I suggest if people wish, we just say that  users of this technique can or cannot
> simultaneously use UDP options.Gorry > >
> >>>>>
> >>>>
> >>>>
> >>>>
> >>>>
> 
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