[ih] principles of the internet

[Matthias Bärwolff]

On 06/01/2010 11:46 PM, John Day wrote:
>> Best effort to me seems absolutely central to the "Internet
>> architecture" -- I'd recommend reading Metcalfe's thesis' chapter 6
>> which really nicely elaborates the notion.
> 
> This is the contribution from Pouzin implemented in CYCLADES, which
> Metcalfe picks up on for the more limited environment of the LAN.
> 

Pouzin's contribution notwithstanding, Metcalfe's thesis' chapter 6 to
me is the first proper elaboration of best effort as a philosophy; I
spare you the copious quotes, it is readily available on the web. Just a
brief one:

\begin{quote}
Imagine that we are a component process in the midst of some large
system. There are two extreme attitudes we might have toward the system
and toward the several component processes upon which we depend. We
might believe the processes around us to be so reliable, irreplaceable,
and interdependent that, if one should fail, there would be little point
in trying to carry on. Or, we might believe the processes around us to
be so unreliable, expendable, and independent that, if some should fail,
there would be considerable potential in our being able to patch things
up to struggle on, weakened, but doing our job. This second attitude is
characteristic of what we call the ``best-efforts'' philosophy of
interprocess communication; it is based on our desire to give the system
our best efforts and, to do so, on our expecting only as much from the
processes upon which we depend.
(pp.\,6-25\,f.)
\end{quote}

To my knowledge, Pouzin has never put it that clearly in writing.

Also, best effort may be argued to have been a principle that was
applied to the Arpanet before Pouzin's Cyclades. Sure, there were VCs,
but, in all, failure and the recovery from such was very much a default
assumption in the whole system (a point that Metcalfe acknowledges, too).

Matthias