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packets</title></head><body>
<div>That was amusing. Another of ITU's attempts to do circuit
switching as packet switching.</div>
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<div>At 9:29 -0500 2011/03/01, Vint Cerf wrote:</div>
<blockquote type="cite" cite>anybody for ATM? :-)</blockquote>
<blockquote type="cite" cite><br></blockquote>
<blockquote type="cite" cite>v</blockquote>
<blockquote type="cite" cite><br>
<br>
</blockquote>
<blockquote type="cite" cite>On Tue, Mar 1, 2011 at 7:25 AM, John Day
<<a href="mailto:jeanjour@comcast.net">jeanjour@comcast.net</a>>
wrote:<br>
<blockquote>Undoubtedly, this is correct.<br>
<br>
But it also occurred to me that this was not such a big deal and was
probably discovered by everyone who went to build one.<br>
<br>
Sending fixed length packets would be more work (or as much work) as
sending variable length ones! In both cases, you need a length
to indicate how much data is there. But in the fixed length case
you have to send more bits than you need and fill out the packet with
zeros.<br>
<br>
Wastes bandwidth and is more work. Not a lot more, but in those days
one saved everyplace you could!<br>
<br>
The historians should remember that for engineers, Laziness is a
virtue! ;-) Not everything that looks like a major insight
to the historians was. Much of it was just common sense.<br>
<br>
Anyone who went to build it would have done the same thing.<br>
<br>
Baran's emphasis was that data was not voice. Voice networks
send streams of fixed length frames, e.g. T-1, because they are
continuously sampling sound. Data is going to be very
different.</blockquote>
<blockquote><br>
<br>
At 22:50 -0500 2011/02/28, Noel Chiappa wrote:<br>
<blockquote> > From: Stephen Suryaputra <<a
href="mailto:ssurya@ieee.org">ssurya@ieee.org</a>><br>
<br>
> Any pointer or reasons why the packet becomes
variable length later on?<br>
<br>
I would assume/guess that the first well-known and wide-scale use was
in the<br>
ARPANet. (Which was pretty much the first general packet network I
know of -<br>
were they any proprietary things before that, does anyone know?)<br>
<br>
The first variable length data items transmitted between compturers
(although<br>
I would tend to doubt they thought of them as packets) might be hard
to track<br>
down.<br>
<br>
It might have been some of the early computer-computer experiments,
e.g. the<br>
kind of thing Larry Roberts did at Lincoln Labs (which definitely had
variable<br>
length messages); another early system that might have had variable
length<br>
data items was SAGE (since that also had computer-computer links
between<br>
centers, although I don't know offhand of a source that talks about
that level<br>
of detail on the communication aspects of SAGE).<br>
<br>
<br>
> A reference would be really appreciated.<br>
<br>
For Larry Roberts' work:<br>
<br>
Thomas Marill, Lawrence G. Roberts, "Toward A Cooperative
Network Of<br>
Time-Shared Computers", Fall AFIPS Conference, October
1966<br>
<br>
For the ARPANET:<br>
<br>
Frank Heart, Robert Kahn, Severo Ornstein, William Crowther,
David Walden,<br>
The Interface Message Processor for the ARPA Computer Network
(1970 Spring<br>
Joint Computer Conference, AFIPS Proc. Vol. 36, pp. 551.567,
1970)<br>
<br>
For SAGE, although there are a number of things about it, for instance
the one<br>
listed here:<br>
<br>
<br>
<a
href=
"http://en.wikipedia.org/wiki/Semi_Automatic_Ground_Environment#Further_reading"><span
></span
>http://en.wikipedia.org/wiki/Semi_Automatic_Ground_Environment#Furth<span
></span>er_reading</a><br>
<br>
Like I said, I don't know of anything there that goes into a lot of
technical<br>
detail on the communication stuff, though. (I looked through a
couple,<br>
including the 'Annals of the History of Computing' issue.) In
particular,<br>
there's a rumor that SAGE had the first email, but the communication
part of<br>
the system especially is so poorly documented in the open literature
I've<br>
never been able to track that down. There is a fair amount on the
AN/FSQ-7<br>
computer, and some on the programming, but the whole communication
aspect<br>
(other than the early radar data transmission) is seemingly not
covered<br>
anywhere.<br>
<br>
Noel</blockquote>
</blockquote>
</blockquote>
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