[e2e] patents on routing algorithms

[David P. Reed]

Jon Crowcroft wrote:
> it is a goal of much recent work (see Sewell et al in sigcomm 05
> "Rigorous specification and conformance testing techniques for network protocols,
> as applied to TCP, UDP, and sockets"
> and various papers
> by Griffin and Sobrinho on Metarouting) 
> to render protocols merely 
> algorithmic specifications that are fed into engines that run them
>
> shame on us as computer scientists that
> we dont use such techniques on a daily basis for
> well-found engineering instead of the handwaving that passes
> for communications work still in the 21st century
>
> it is a technical AND ethical goal to make it so
> and should be a duty on all of us to get the law to recognize it
>
>   
That's a plausible point of view.   I heartily disagree, however.  In 
1974 or so, our research group (Saltzer, Clark, Reed, Liskov, Svobodova, 
as I recall) decided that a *crucial* aspect of distributed systems was 
that they exhibited "autonomy", which implies a serious notion of loose 
coupling, flexibility, revisability, etc.  That set of attributes are 
crucial, leaving them out for the sake of formal methods is just another 
Procrustean bed, where they are the Feet.

*Protocols* are techniques for achieving communications in the face of 
uncertainty about who is on the other side of the network.  Not just an 
unreliable network in the middle, but an uncertainty in a very 
fundamental sense about what is on the other side.

In "distributed systems" that must function in the real world, a core 
and *essential* concept is that one must specify parts of the system to 
work "right" EVEN IF THE DEFINITION OF RIGHT CANNOT BE WELL-DEFINED 
MATHEMATICALLY.

To someone who speaks English as a protocol, this is obvious.   I can 
try to convince you, for example, by the words above that I am right.   
And I am using English correctly, and this can be verified.  But it has 
nothing to do whatsoever with being able to prove that you *will* agree 
with me at the end of the conversation.  Maybe it will take more 
conversations, maybe not.

But a protocol is not an algorithm executed by a complete set of formal 
machines, though some protocols (a small subset might be in that 
category).  That is a sad, little boring and utlimately trivial subset 
of the "protocols" of the world.   Maybe it makes small-minded 
mathematicians happy because they can close off a "formal system" and 
prove theorems, as if proving theorems is the desired endpoint of system 
design.    But the ability to prove theorems is not the test of a 
*useful* protocol set - neither of engineering value, nor of human 
value.   The ability to communicate (which cannot be formalized in any 
way I know) is the correct test.   The Internet is one example of a 
system that succeeds in communicating, and there really was NOT a need 
to define a formal specification of a collection of machines to achieve 
that result.