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[ih] ARPAnet Type 3 packets (datagrams)

Yea, that jibes with my recollection.

And "datagrams" were in the first version of X.25 in 76, or was that 
Fast Select?

At 18:45 -0500 2009/11/25, Vint Cerf wrote:
>the type 3 packets were explicitly used for real-time packet voice 
>and later packet video experiments. This would have been in the 1975 
>time frame (but Danny Cohen and Steve Casner would know for sure as 
>they were at ISI; Lincoln Labs was also involved and we used their 
>packet digitizers/compressors. Duane Adams managed the packet voice 
>activity during the time I was at DARPA so I am copying him too. I 
>don't seem to have steve casner's email but I think he is now at 
>On Nov 25, 2009, at 6:05 PM, Richard Bennett wrote:
>>I've discussed this issue recently with a key member of the IMP 
>>team at BBN and he (unsurprisingly) has a very different 
>>recollection of the facts. A datagram mode was added to the IMP and 
>>to X.25 switches fairly early. Datagrams appeared on research 
>>networks well before TCP/IP was defined; CYCLADES had them in 1972.
>>The BBN people have not been able to tell me whether the NWG ever 
>>took advantage of the datagram mode in the IMP; that was outside 
>>their department.
>>Bob Braden wrote:
>>>My memory was that BBN included type 3 (Uncontrolled or "raw") 
>>>messages in the IMP protocol as an experiment, which they then 
>>>considered too dangerous to use . BBN disabled them at (almost?) 
>>>all hosts (almost?) all the time, I believe.  TCP/IP used standard 
>>>reliably-delivered IMP traffic. But the facility must have been 
>>>enabled for the packet voice experiments shown in that marvelous 
>>>My memory on this point is hazy, but probably Vint can correct me. 
>>>When Barry Leiner became (D)ARPA Program Manager for the Internet 
>>>research program, he became determined that BBN should try using 
>>>Type 3 IMP-IMP packets for normal TCP/IP flows. He complained to 
>>>the ICCB/IAB that BBN was resisting.  He insisted that the 
>>>experiment be tried for 24 hours. Unfortunately I don't recall 
>>>that the experiment ever happened;
>>>it is more than possible that BBN stone-walled his demand.
>>>Bob Braden
>>Richard Bennett
>>Research Fellow
>>Information Technology and Innovation Foundation
>>Washington, DC