Subject: Re: LLMNR is done

From: Bernard Aboba <[email-masked]>
Date: Mon, 26 Jan 2004 08:53:33 -0800 (PST)

>	maybe a stupid question (sorry) - has the interop issue with Apple
>	Rendezvous implementaiton resolved?  if not, i don't think the
>	protocol useful.  of course both Apple side as well as LLMNR side
>	should make effort to make it interoperable (Apple cannot just
>        force LLMNR be compatible with Rendezvous), in my opinion.

On  August 29, 2003 Olaf Kolkman posted the following message to the
DNSEXT WG mailing list summarizing the situation:

http://ops.ietf.org/lists/namedroppers/namedroppers.2003/msg01620.html

In this message, he made the request that *all* changes required to
achieve interoperability be provided.  No answer was received.

Subsequently, I went back over the Rendezvous documents to look at the
differences.  These go well beyond the TTL and multicast address choices.
mDNS and LLMNR have taken different approaches on more than half a dozen
different points, many going back to the earliest drafts.  The
differences are more than cosmetic because the protocols began from
different assumptions and problem statements, and evolved in separate
ways from the beginning.  At this point, the protocols only share some
similarities in the use of the DNS packet format, and even here the
differences are substantial.

To sum up the situation, on October 6, 2003, Olafur posted the following
reply:
http://ops.ietf.org/lists/namedroppers/namedroppers.2003/msg01872.html

Known differences between Rendezvous and LLMNR
----------------------------------------------
a. Rendezvous uses multicast responses.  LLMNR uses unicast.
b. Rendezvous allows proxying; LLMNR does not.
c. Rendezvous uses the header bits differently, including AA, TC, RD,
RA, AD, CD
d. Rendezvous and LLMNR uses different retransmission strategies and
timers.
e. Rendezvous uses ".local" extension, LLMNR does not.
f. Rendezvous requires TTL=255; LLMNR uses TTL=1.
g. LLMNR supports unicast queries; Rendezvous does not.
h. LLMNR and Rendezvous use different multicast addresses and ports.

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From: Ralph Droms <[email-masked]>
Date: Tue, 27 Jan 2004 14:01:05 -0500

Following up on Bernard's assessment of the relationship between LLMNR and 
Rendezvous:

At 08:53 AM 1/26/2004 -0800, Bernard Aboba wrote:
>[...] The

My understanding is that LLMNR is designed:

* to avoid interference with and pollution of DNS information
* to transition gracefully to DNS
* to avoid generating bogus .local queries
* to avoid redfining key IP concepts like TTL
* to use TTL correctly so that LLMNR traffic is confined to a link, rather
   than redefining TTL to provide security (whch it doesn't provide, anyway)

I'm working here from observation,  not from any requirements explicitly set
out in <draft-ietf-dnsext-mdns-29.txt> or the dnsext WG charter...

- Ralph