Subject: RE: periodic messages (was RE: comments on requirements draft 04)

From: "Hattig, Myron" <[email-masked]>
Date: Thu, 10 Aug 2000 08:06:21 -0700

Agreed. Unless there's further input, I'll change the text as you suggest.
Here is one of the samples.

>    These scenarios require that hosts be able to discover DHCP servers
>    both initially, at startup, and during normal operation.

-myron

---

From: Stuart Cheshire <[email-masked]>
Date: Tue, 15 Aug 2000 20:04:28 -0700

>Periodic actions ARE required.

>I didn't think the requirements were written in such a way that
>would automatically require such a protocol - that's why in the
>previous note I made the distinction between ACTIONs and MESSAGES.

I think this is one of those, "If a tree falls in a forest and no one is 
around..." philosophical questions. If a host performs an action and 
sends no messages, did it really perform any action?

Protocol design concerns the externally visible behaviour of devices, not 
their internal implementation. Any implementation that generates the 
correct externally visible behaviour is valid.

It is only useful for us to design protocols by talking about the content 
of the messages on the wire, and the times at which they are sent. 
Everything else is an implementation decision.

>I'm concerned that your statements over periodic messages conflicts with
>the draft. Specifically, the draft states that scalability is not a
>major issue for zeroconf, as it is expected that zeroconf will be used
>in small evironments.

Network scalability is not the only concern.

Small networks may also slow links, so wasting bandwidth for no reason is 
always a bad idea.

Another big concern is power management. Modern computers go to sleep to 
conserve power. Any requirement for periodic actions interferes with that.

Stuart Cheshire <[email-masked]>
 * Wizard Without Portfolio, Apple Computer