[Int-area] Re: [IPv6]Re: [tsvwg] Re: UDP options [was IP Parcels and Advanced Jumbos (AJs)]

On Wed, Nov 20, 2024 at 10:23 AM Templin (US), Fred L
<[email protected]> wrote:
>
> Hi Tom,
>
> > -----Original Message-----
> > From: Tom Herbert <[email protected]>
> > Sent: Wednesday, November 20, 2024 10:08 AM
> > To: Templin (US), Fred L <[email protected]>
> > Cc: Gorry Fairhurst <[email protected]>; [email protected]; C. M. Heard <[email protected]>; [email protected]; int-area
> > <[email protected]>; 6man <[email protected]>; TSVWG <[email protected]>
> > Subject: Re: [IPv6]Re: [tsvwg] Re: UDP options [was IP Parcels and Advanced Jumbos (AJs)]
> >
> > On Wed, Nov 20, 2024 at 9:51 AM Templin (US), Fred L
> > <[email protected]> wrote:
> > >
> > > 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,
> >
> > What is the use case for sending a single segment of 1-octet? What
>
> I don't have a use case, but such a parcel would be compliant with the spec.
> I don't see a reason to constrain the spec to forbid such a construct.
>
> > would be the use case of sending segments with size less than Minimum
> > MTU?
>
> In the LTP protocol at least, the receiver waits to receive many segments before sending
> back a series of very small (less than 100 octet) acknowledgements. When there are lots
> of segments, LTP often sends back a barrage of short acknowledgements in ordinary IP
> packets. These could instead be bundled as IP parcels.

Fred,

That is an interesting use case, but I think packing multiple acks
into a single packet is more of a transport layer issue than a network
layer issue and is independent of using larger MTUs. I suggest that
this can be solved by changing LTP to carry more information in a
packet, or if changing the protocol is prohibitive then maybe a new
UNSAFE UDP option would do the trick. Either way this seems like an
end-to-end issue so we shouldn't have to expose this to routers (i.e.
a HBH option isn't warranted).

Tom

>
> Thank you - Fred
>
> > Tom
> >
> > >
> > > 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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