[ih] mssage vs. packet (was: Re: Early Internet history)

[Jack Haverty]

As The Judge recently pointed out, it's impossible to define colloquial
technical terms like "email".  I suspect "message" and "packet" are
similarly imprecise.

Personally, I've always thought that the distinction is that a "message"
is a self-contained and complete unit of information, that makes sense
to both the endpoint sender and receiver.  You send a whole "message" to
some destination, and the destination can only use it after the entire
message is received.

A "packet" is something that some communications mechanism uses to
actually transport data, driven by pragmatic and engineering concerns.
E.g., packet sizes might be set based on expected error rates due to noise.

So, messages get chopped up into packets; or maybe even several messages
get packaged into one packet.  It's up to the communications machinery
(or its designers) to decide, based on local conditions.

Messages get sent between users, who decide what constitutes a complete
unit of useful information.

Of course, one player's packets might also actually be another player's
messages.  SMTP messages get carved up into IP datagrams which were
carved up into pieces that were sent between endpoint IMPs, which were
carved up into other pieces that actually traversed wires between IMPs.
These chunks were packets or messages depending on your viewpoint.

/Jack



On 07/07/2018 04:15 PM, Dave Crocker wrote:
> 
>> Kleinrock's analysis was for message switching but the mathematics of 
>> message switching and packet switching are essentially comparable 
>> especially when you consider variable length messages.
> 
> 
> Howdy.
> 
> A question to the group...
> 
> That distinction coincidentally surfaced in a discussion a couple of 
> months ago, after some decades of my not hearing it.
> 
> I know what it meant on the Arpanet.  And I know what wikipedia and some 
> other entries say about it.  But while the ability to handle smaller 
> chunks independently -- and even in an overlapping manner -- encourages 
> some useful performance improvements, I find myself generally thinking 
> of them as the same category of communications technology.
> 
> Namely:  Discrete segments of data being handled through a network. 
> Certainly for some form of multiplexing and possibly with dynamic 
> routing.  (These days, we'd take stat mux and dynamic routing as 
> inherent, but my recollection is that 45 years ago, those were 
> variations being played with.)
> 
> I'm not looking to re-start the religious wars on the distinction but am 
> curious whether, from the perspective of those 45 years and global 
> scaling, it is fair to have most discussions -- I emphasize most, not 
> all -- treat them as the same construct?
> 
> If not, why not?
> 
> 
> d/
>