Subject: Re: Naming and site-local addresses

From: Dan Lanciani <[email-masked]>
Date: Wed, 13 Nov 2002 00:09:22 -0500 (EST)

Keith Moore <[email-masked]> wrote:

|Neither does it scale to expect all hosts to maintain
|enough information to let them do routing. 

On the contrary, distributed host-based routing is one of the few solutions
that does scale well.  The availability of resources to deal with the routing
grows directly in proportion to the consumers of those resources.  It is
traditional centralized routing that suffers from issues of scale, though
these are variably exaggerated and minimized depending on the case that is
being argued.

Personally I would have liked to see routing confined to the stack and hidden
from applications with portable identifiers or a similar indirection mechanism.
Unfortunately, this would have conflicted with the address allocation business
model as currently envisioned, so the functionality (or, rather, a subset of
the functionality) was percolated up to the application layer.  So it goes.

				Dan Lanciani
				ddl@danlan.*com
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From: Keith Moore <[email-masked]>
Date: Wed, 13 Nov 2002 08:33:33 -0500

> grows directly in proportion to the consumers of those resources.  

that incorrectly assumes that the only 'resource' in question is cpu time

offhand:

a. you have to get the information to the hosts to allow them to do routing
b. some hosts are mobile and/or intermittently connected and would have
   a difficult time keeping up with routing updates - also they could
   consume significant bandwidth to those hosts
c. consistency of routing is harder to acheive with so many hosts involved
d. routing updates would take longer to propagate 
e. unless you expect hosts to do source routing, having them do routing
   doesn't relieve the network of the need to do routing.  
f. source routes consume bandwidth
g. source routes are less resiliant to changes in network configuration
   (e.g. link failure) near the destination
h. you can't expect hosts to adhere to policy for use of other portions
   of the network