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 <go...@erg.abdn.ac.uk> > Sent: Wednesday, November 20, 2024 12:06 AM > To: lloyd.w...@yahoo.co.uk; C. M. Heard <he...@pobox.com>; > to...@strayalpha.com > Cc: int-area <int-area@ietf.org>; 6man <i...@ietf.org>; TSVWG <ts...@ietf.org> > Subject: Re: [tsvwg] Re: UDP options [was IP Parcels and Advanced Jumbos > (AJs)] > > On 19/11/2024 23:58, lloyd.w...@yahoo.co.uk 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 > > lloyd.w...@yahoo.co.uk > > 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, to...@strayalpha.com > > <to...@strayalpha.com> 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 <he...@pobox.com> 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 <he...@pobox.com> 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 > >>> <Fred.L.Templin=40boeing....@dmarc.ietf.org> 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 <brian.e.carpen...@gmail.com> > >>>> Sent: Saturday, September 28, 2024 2:20 AM > >>>> To: Gorry (erg) <go...@erg.abdn.ac.uk> > >>>> Cc: Joe Touch <to...@strayalpha.com>; Templin (US), Fred L > >>>> <fred.l.temp...@boeing.com>; Tim Chown <tim.ch...@jisc.ac.uk>; > Internet Area <Int-area@ietf.org>; IPv6 List <i...@ietf.org>; tsvwg IETF list > <ts...@ietf.org> > >>>> 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), <go...@erg.abdn.ac.uk> wrote: > >>>> > >>>> > >>>>> See below> On 28 Sep 2024, at 04:05, Brian E Carpenter > >>>>> <brian.e.carpen...@gmail.com> wrote:> > Joe,> On 28-Sep-24 03:13, > to...@strayalpha.com wrote:>>>> On Sep 27, 2024, at 7:58 AM, Templin (US), > Fred L <Fred.L.Templin=40boeing....@dmarc.ietf.org> > 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 > > > >>>>> > >>>> > >>>> > >>>> > >>>> > > -------------------------------------------------------------------- > IETF IPv6 working group mailing list > i...@ietf.org > List Info: https://mailman3.ietf.org/mailman3/lists/i...@ietf.org/ > -------------------------------------------------------------------- _______________________________________________ Int-area mailing list -- int-area@ietf.org To unsubscribe send an email to int-area-le...@ietf.org
