[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[ih] ARPAnet Type 3 packets (datagrams)

At 15:03 +0100 2009/11/26, R?mi Despr?s wrote:
>Le 26 nov. 2009 ? 13:42, John Day a ?crit :
>>  I remember seeing text for both a "datagram" 
>>and Fast Select.  They may have been 
>>contributions. But I thought I remembered 
>>slightly more than placeholder text in the 
>>Orange book for datagrams.
>>  And that something was put in under pressure 
>>but no one ever did it and it was taken out 
>>fairly soon.
>>  But if it wasn't in the Orange book and it was 
>>taken out, when was it put in!?  ;-)
>* CCITT Recommendation X.25 (1976) Orange Book - No datagram
>* CCITT Recommendation X.25 (1980) Yellow Book - Datagram added
>* CCITT Recommendation X.25 (1984) Red Book - Datagram deleted

Okay, then what I remember seeing were 
contributions.  Was the "datagram" in the Yellow 
Book, a datagram or Fast Select?

>>  The only influence the researchers brought to 
>>that early debate (I think) was Louis 
>>convincing them to alight LAPB more closely to 
>In my recollection, X.25 was technically 
>finalized before all variants of HDLC were 
>stabilized in ISO.
>Harmonization being found necessary, in 
>particular by IBM which was then leader on the 
>subject in ISO, the layer 2 of X.25 (LAPB) was 
>eventually aligned with the HDLC-Asynchronous 
>Balanced Mode.

So was that done for the Yellow Book as well?

Take care,

>>  At 10:35 +0100 2009/11/26, R?mi Despr?s wrote:
>>>  Le 26 nov. 2009 ? 06:34, Vint Cerf a ?crit :
>>>>  + remi despres
>>>>  +steve casner
>>>  + Barry Wessler
>>>>  John, I am pretty sure that X.25 did not 
>>>>have datagrams in the same sense as 
>>>>Cyclades/Cigale or even ARPANET. There was a 
>>>>fast select but I thought it came later 
>>>>rather than earlier in the X.25 story?
>>>  The first X.25, published in 1976 in the 
>>>CCITT Orange book, had only virtual circuits 
>>>  They were soon deployed in Canada (Datapac), 
>>>in France (Transpac), and the US (Telenet).
>>>  Four years later, datagrams were introduced in X.25.
>>>  They were only optional, while VCs remained mandatory.
>>>  Quite different from IMP-to-IMP packets of 
>>>Arpanet and Internet datagrams, they had some 
>>>control by customers of packet drop conditions.
>>>  In my recollection, they had been added under 
>>>political pressure from some administrations 
>>>that didn't operate X.25 networks.
>>>  Four years later, as no X.25 operator had 
>>>plans to implement them, they were deleted 
>>>from X.25.
>>>  Regards,
>>>  RD
>>>>  v
>>>>  On Nov 25, 2009, at 7:14 PM, John Day wrote:
>>>>>  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 PARC.
>>>>>>  vint
>>>>>>  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.
>  >>>>>>
>>>>>>>  RB
>>>>>>>  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 video.
>>>>>>>>  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