Subject: LL10 applications assume addresses are routable?

From: Stuart Cheshire <[email-masked]>
Date: Fri, 14 Feb 2003 23:25:30 -0800

Several people have said:

>Many applications fundamentally assume
>addresses of communicating peers are routable

I submit that this is utter nonsense.

Applications (aside from a few specialized network debugging tools like 
traceroute) care only that a given destination address will deliver a 
packet to the right destination. The fact that the packet may get there 
via routing is an implementation issue, of which the application has no 
care.

Stuart Cheshire <[email-masked]>
 * Wizard Without Portfolio, Apple Computer, Inc.
 * www.stuartcheshire.org

---

From: Keith Moore <[email-masked]>
Date: Mon, 17 Feb 2003 00:24:46 -0500

> I submit that this is utter nonsense.

It depends on how you interpret 'routable'.  I agree with you that very
few apps care how their packets get from one point to another, as long as
they get there.  But if you interpret 'routable' in the sense of 'having the
properties of a normal IP address, as opposed to those of a LL address', then
it's a very reasonable statement. 

A slight change of wording might help.  e.g. 'many applications fundamentally
assume that addresses are uniquely bound to hosts within the temporal and
topological scope of the application, and/or that addresses used by pairs of
communicating hosts are also usable by other hosts participating in the same
application.'

Keith