[ih] UDP Length Field?

[Scott O. Bradner]

Danny said he used the bypass for his voice experiments - see

https://www.youtube.com/watch?v=av4KF1j-wp4&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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