[e2e] Historical question: Link layer flow control / silent discard

John Day jeanjour at comcast.net
Tue May 28 20:47:33 PDT 2013


No one took anything but Class 4 seriously.  Class 0 was to keep 
CCITT SGVIII quiet, Class 1 was to placate CCITT SGVII, Class 2 was 
for the European users who had to buy X.25 and thought (wrongly, 
which we knew but couldn't prove at the time) that it would be 
simpler because X.25 was "kind of" reliable (not), Class 3 was to 
keep the Germans quiet.

Class 4 was an improved INWG96 that incorporated at least partially 
Watson's results from delta-t.  INWG96 was basically the transport 
protocol for CYCLADES.

The day Western Union and CSC were awarded the AutoDinII contract, I 
predicted it would fail. After all, CSC were the ones that tried to 
use the NCP control channel to send mail and built a copy of the 
ARPANET that ran 7 times slower!  That takes talent.

Take care,

At 9:12 PM -0400 5/28/13, Barney Wolff wrote:
>Some poor deluded folks (I among them) did implement ISO TP classes 1 & 3
>over X.25 .  Years later, replaced (me again) by TP0 over TCP.  As this
>was at Western Union and then ATT, perhaps excusable as Bellheadness, or
>youthful folly.
>On Tue, May 28, 2013 at 05:02:57PM -0400, John Day wrote:
>>  Just for the record and then I will let this discussion go on, but
>>  X.25 was not at the core of the OSI Model.  It is true that there
>>  were some people Bob's age (we called them the old guard) who thought
>>  they wanted to X.25 products and say it was OSI, but no one else had
>>  any intention of doing OSI products with X.25.  Nor was it at the
>>  core of OSI Network Layer.  Most of those people would have said CLNP
>>  was the core of the OSI Network Layer.  In fact, OSI was designed to
>>  handle multiple network technologies, which is why the Network Layer
>>  was structured the way it was.  OSI allowed both connection-oriented
>>  and connectionless operation.  The fact that no one ever defined for
>>  OSI a connection-oriented network layer protocol but did define a
>>  Connectionless Network Layer Protocol (CLNP) speaks for itself.
>>  End of myth-busting.

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