Subject: Re: New issue: When to configure a LL address

From: Stuart Cheshire <[email-masked]>
Date: Wed, 12 Mar 2003 23:25:19 -0800

Philip Nye wrote:
>This begs other questions like why do you need to reboot the
>base station anyway? Wouldn't you expect connections to be
>broken when you are rebooting your router?

Philip, you have made many smart comments in the past, which makes this 
one all the more surprising.

I am sorry to have to say that I am shocked and horrified to see this 
comment on an IETF mailing list.

If one were giving an introductory networking lecture and had to describe 
the single most important feature of the Internet that distinguished it 
from its predecessors, it is this:

    The Internet uses stateless connectionless packet switching.

The whole point of the Internet is that all the connection state is at 
the endpoints; you can reboot (or even replace) intermediate nodes 
without breaking all the connections going through those nodes.

Arguably the most famous research paper in the history of networking is 
"End-To-End Arguments In System Design" by Saltzer, Reed and Clark. 
Anyone who has not read it, should.

[Aside: This is one of the (many) reasons to dislike NAT: NAT introduces 
a point of failure for Internet connections where previously there was 
none.]

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

---

From: "Philip Nye" <[email-masked]>
Date: Fri, 14 Mar 2003 12:16:40 -0000

> From: "Stuart Cheshire" <[email-masked]>
>
> Philip Nye wrote:
...
> without breaking all the connections going through those nodes.

I stand humbled! I obviously should have said "while you are rebooting.."
for clarity.

Once the router is up and running again, then of course the connections will
operate (as they will if you have multiple routes etc.) However, the fact
that the station is booting and the time to do so are not known to the
host - the connection simply stops working and the host does not know how
long to wait before concluding that it should take an alternative action (if
one is available).

Philip