Subject: Re: Question on Stewart's last mDNS item

From: Bernard Aboba <[email-masked]>
Date: Sun, 16 Sep 2001 08:17:42 -0700 (PDT)

> >Did svrloc crash & burn without me noticing?  Or is there a
> >terrible gap in coverage?
> 
> A while back I promised you an answer to this question. It took me a 
> while, but here it is.
> 
> I realized that one goal of Multicast DNS was to replace AppleTalk NBP,

Indeed, replacement of legacy protocols (including Novell IPX and
NetBIOS) was one of the major goals discussed at the original
Zeroconf BOF. I also believe that this goal has been at the root of some
of the major arguments we've had about the overall direction of the mDNS
effort. 

Unfortunately, until now this goal was never articulated, and therefore
did not find its way into the Zeroconf requirements document. So in
writing the mDNS draft, we assumed that the Zeroconf WG had decided that
it wasn't important.

> but no one had actually written down precisely what is required to 
> replace AppleTalk NBP. 

If, as you suggest, we have been working on the solution to a problem
whose requirements have not yet been defined, then I believe that this
represents a major deficiency in the Zeroconf requirements document. 
Section 2.2.1 of draft-ietf-zeroconf-reqts-09.txt mentions that:

"A mechanism to support DNS resolver interfaces in the zero configuration
environment is required. 

Requirement:
- MUST support DNS application layer interfaces as described in RFC 1123,
  section 6.1 [RFC 1123]."

Section 2.2.2 mentions that:

"Requirement:

- MUST allow a host to determine if its name is unique. Then not
unique, notify the user or configuration software so that another name may
be chosen and similarly verified."

That's essentially it for the zeroconf name resolution requirements.