For those of you who have missed it, here
http://www.google.com/search?q=cache:web.mit.edu/Saltzer/www/publications/endtoend/endtoend.pdf+clark+end+to+end&hl=en
is the paper some of us mention, "END-TO-END ARGUMENTS IN SYSTEM DESIGN"
by Saltzer, Reed, and Clark.
The abstract is:
This paper presents a design principle that helps guide placement of functions among the modules of a distributed
computersystem. The principle, called the end-to-end argument, suggests that functions placed at low levels of a
systemmay be redundant or of little value when compared with the cost of providing them at that low level. Examples
discussedin the paper include bit error recovery, security using encryption, duplicate message suppression, recovery
from system crashes, and delivery acknowledgement. Low level mechanisms to support these functions are justified
onlyas performance enhancements.
It was written in 1981 and is undiminished by the subsequent decades.
Nathan Myers
ncm@zembu.com