Subject: LL19 Do not use v4LL source address to non-v4LL destinations

From: Stuart Cheshire <[email-masked]>
Date: Tue, 11 Feb 2003 19:35:52 -0800

Bernard Aboba made some good arguments here, in my opinion, about why the 
perceived danger is pretty much a red-herring.

In reality, communication between routable and LL will only occur 
commonly between compatible hosts (and in that case, those compatible 
hosts derive worthwhile benefit from being able to communicate).

In practice, Mac OS 9 and Mac OS X have both implemented communication 
between routable and LL for a long time, and no problems have been 
observed or reported.

Robert Elz gave an example of a user manually typing IP addresses on the 
command line. I do not believe that anything in this document changes the 
fact that when a user manually types IP addresses on the command line, 
they may type an address that for whatever reason fails to achieve 
successful communication, and may result in wasted packets being sent. 
Ten years ago, if I walked into your office with my laptop manually 
configured to 36.186.224.17, and you typed "telnet 36.186.224.17" on your 
computer, then your computer would send wasted packets all the way to 
Stanford, and successful communication would not be established. I agree 
that sending wasted packets into the Internet is not a good thing, but I 
think that we should also be careful not to regard the mere potential for 
an occasional wasted packet as a monumental disaster.

I oppose LL19.

Stuart