[ih] UDP Length Field?

Wed Dec 2 15:32:48 PST 2020

this is WONDERFUL! I don't think I knew about this or, if I did, it was
long forgotten.
vint

On Wed, Dec 2, 2020 at 6:15 PM Scott O. Bradner via Internet-history <
internet-history at elists.isoc.org> wrote:

> Danny said he used the bypass for his voice experiments - see
>
> https://www.youtube.com/watch?v=av4KF1j-wp4&amp;feature=youtube_gdata
> at 31:25
>
> Scott
>
> > On Dec 2, 2020, at 5:40 PM, Jack Haverty via Internet-history <
> internet-history at elists.isoc.org> wrote:
> >
> > At the time (late 70s), there was another issue related to UDP and
> > real-time applications.   The Internet was in its "fuzzy peach" stage of
> > development, where almost all long-haul links were established by
> > interconnecting gateways at user sites to the ARPANET.
> >
> > The ARPANET was effectively a "byte stream" service, where everything
> > sent in from a host was delivered to the host at the other end intact,
> > in order, and reliably.  This made it difficult to imagine much useful
> > experimentation with UDP and lossy transmission, since the ARPANET would
> > never lose anything, and retransmit internally as needed to deliver the
> > data in order.
> >
> > There was an "uncontrolled mode" of operation possible within the
> > ARPANET, which wouldallow a user computer to send packets bypassing all
> > of the reliability mechanisms.   That could be used to deliver datagram
> > Internet service.   However, the ARPANET managers (at DCA and BBN) were
> > extremely reluctant to permit hosts (e.g., gateways) to use that mode,
> > for fear that the uncontrolled traffic would crash the ARPANET.   I
> > recall being involved in several "discussions" about using ARPANET
> > uncontrolled mode for Internet experiments, but I don't remember any
> > permissions ever being granted.   John Kristoff's mention of the
> > problems today's operators are facing was a reminder that the issue of
> > how to control datagram service still has not been solved -- other than
> > by turning it off.
> >
> > UDP functionality is about more than defining a protocol....
> >
> > /Jack Haverty
> >
> >
> > On 12/2/20 12:13 PM, Vint Cerf via Internet-history wrote:
> >> David Reed's timing comports with what I remember. I got to ARPA in Sept
> >> 1976. TCP2 came out in (early?) 1977, then the split of TCP/IP; TCP 2.5,
> >> TCP 3 (at which point I think the IP doc and new TCP doc appear. Then
> >> TCP/IP v4 in 1978 (from memory; have not checked RFCs). David is also
> right
> >> about Internet and TCP going along in parallel with ARPANET and
> documents:
> >> Internet Experiment Notes. We did publish RFC 675 in Dec 1974 Internet
> >> Transmission Control Protocol.
> >>
> >> I have a fairly clear recollection of being at USC/ISI with Jon, Danny
> >> Cohen and David Reed in 1977 discussing the real-time application needs
> >> that TCP would not satisfy owing to retransmission delays.
> >>
> >> v
> >>
> >>
> >>
> >>
> >> On Wed, Dec 2, 2020 at 1:07 PM David P. Reed <dpreed at deepplum.com>
> wrote:
> >>
> >>> Noel - you are plain wrong that UDP happened after the split.  UDP was
> >>> created in 1977, by me and Jon Postel and Danny Cohen, primarily. The
> >>> "spec" was a sketch in Jon's notes, not an RFC. (RFC's dont tell the
> full
> >>> history, not by far! Especially back then, where the TCP working group
> was
> >>> working on its own, separate from the ARPANET process of RFC's. Our
> work
> >>> was in email and in meetings. The split was done on the blackboard at
> >>> Marina del Rey, with IP, TCP and UDP all defined. UDP at that time
> >>> satisfied Danny, me, and John Schoch who were the main "users"
> demanding a
> >>> datagram user level.
> >>>
> >>>
> >>>
> >>> As I recall, you, Noel, were not involved at all in the Internet
> project
> >>> at that time (nor was Dave Clark directly). I was the guy. I had spent
> >>> summer 1976 designing DSP, and in the fall Bob Kahn and Vint strongly
> >>> discouraged continuing with DSP for LANs, and encouraged me to join
> the TCP
> >>> project to bring my ideas into that framework. Which I did, until early
> >>> 1978, when demands of completing my doctoral thesis forced me to stop
> >>> direct participation and Dave Clark became involved.
> >>>
> >>>
> >>>
> >>> As I recall, you were engaged with token ring hardware during that
> time,
> >>> not TCP or IP, along with Clark and Pogran, right?
> >>>
> >>>
> >>>
> >>> PS: I've given up, mostly, on trying to help clarify Internet
> "history".
> >>> Because of the egos involved seeking credit as the "father", claiming
> the
> >>> Internet was just ARPANET (BBN) and not a separable concept about
> >>> internetworking, etc. what I find is that books like Katie Hafner's BBN
> >>> propaganda are accepted as the truth, along with propaganda from UCLA
> etc.
> >>> In fact, the history is far more complex than these tales of "heroic"
> >>> inventions of things like the "@" that is said to be Tomlinson's only
> >>> contribution! (Ray did FAR more, including sorting out sequence
> numbering
> >>> and encouraging the use of 32-bit oriented frame structures, even on
> 36-bit
> >>> machines like PDP-10's and GE645's.
> >>>
> >>>
> >>>
> >>> I have very little interest in getting "credit" to stroke my ego,
> unlike
> >>> some in the community. But I do wish people would get it right.
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> On Sunday, November 29, 2020 2:28pm, "Vint Cerf" <vint at google.com>
> said:
> >>>
> >>> Noel,
> >>> yes, we did the split to support real-time and then concluded that UDP
> was
> >>> the best way to present the "service" vs running over raw IP.
> >>> v
> >>>
> >>> On Sun, Nov 29, 2020 at 1:46 PM Noel Chiappa via Internet-history <
> >>> internet-history at elists.isoc.org> wrote:
> >>>
> >>>>> From: Craig Partridge
> >>>>
> >>>>> Recall that the creation of UDP meant TCP and IP had to be split
> >>>> apart
> >>>>
> >>>> No. The TCP/IP split _long_ predates the creation of UDP. The former
> is
> >>>> already apparent as of IEN-21, "TCP 3 Specification" (see pages 56
> and 59
> >>>> for
> >>>> the IP and TCP header formats), from January 1978. UDP is IEN-71, from
> >>>> 21-Jan-79 (and as I recall, there was not a lengthy discussion before
> it
> >>>> came
> >>>> out).
> >>>>
> >>>> Oh, looking at IEN-71, in the packet format description, it says
> "data,
> >>>> padded
> >>>> with zero octets at the end to make a multiple of two octets". So
> Vint's
> >>>> comment
> >>>> about the length was right on target.
> >>>>
> >>>> It mentions host name lookup (_not_ DNS; it was servers which had a
> copy
> >>>> of
> >>>> the host table) as the intended appplication. Time was also early,
> IIRC.
> >>>> My
> >>>> recollection is that TFTP was the first non-datagra protocol (i.e. not
> >>>> single-packet transactions) to make use of UDP, but my memory mmay be
> >>>> failing
> >>>> me there.
> >>>>
> >>>>   Noel
> >>>>
> >>>> --
> >>>> Internet-history mailing list
> >>>> Internet-history at elists.isoc.org
> >>>> https://elists.isoc.org/mailman/listinfo/internet-history
> >>>
> >>> --
> >>> Please send any postal/overnight deliveries to:
> >>> Vint Cerf
> >>> 1435 Woodhurst Blvd
> >>> McLean, VA 22102
> >>> 703-448-0965 <(703)%20448-0965>
> >>> until further notice
> >>>
> >>
> >>
> >
> > --
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> > Internet-history at elists.isoc.org
> > https://elists.isoc.org/mailman/listinfo/internet-history
>
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