Subject: Re: [Sipping] P2P why not multicast DNS for discovery?

From: "Samuel Osorio Calvo" <[email-masked]>
Date: Mon, 07 Feb 2005 16:10:06 +0100

As far as I know there are two drafts which covers the multicast
approach for name resolution:
*draft-cheshire-dnsext-multicastdns-04.txt
*draft-ietf-dnsext-mdns-33.txt

I read them quite a long ago so correct me if they have been updated or
deprecated. They would need to be adapted to a large network, such as a
complete VoIP world-wide network, but they could be used as an
alternative for the "classical" DNS if a central resolver is not
reachable or even for small communities as the use cases proposed here
(ad-hoc chat, firemen without external connectivity).

Moreover mDNS can be easily interoperable with existing DNS UAs so the
adaptation of mDNS would solve some use cases with "little" changes in
the UAs since they must be aware of their identity and react if somebody
ask for it. It is therefore not required a full implementation of an
underlying DHT mechanism.

Corrections? Thoughts??

Samuel Osorio Calvo
Phone: (+31) 35 5248126

THALES Communications
P.O. Box 88, 1270 AB  Huizen, The Netherlands
Bestevaer 46, 1271 ZA  Huizen, The Netherlands

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From: Marshall Eubanks <[email-masked]>
Date: Mon, 7 Feb 2005 15:02:19 -0500

The Cheshire draft is available from 
http://www.multicastdns.org/
it is a by-product of ZeroConf work. As such, it requires ASM.

Is the " complete VoIP world-wide network" multicast enabled ? What
should be done if pieces
are not ? I can see real problems here is making this available
everywhere (i.e.,
multi-domain), with the current protocols.

Regards
Marshall Eubanks

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From: Juha Heinanen <[email-masked]>
Date: Mon, 7 Feb 2005 23:05:34 +0200

Marshall Eubanks writes:

 > should be done if pieces are not ? I can see real problems here is
 > making this available  everywhere (i.e.,

i agree that it is impractical to design a global p2p solution on
muticasting, because multicasting has not really happeded internetwide.

-- juha

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From: Marshall Eubanks <[email-masked]>
Date: Mon, 7 Feb 2005 21:23:12 -0500

There has been discuss of a native support of application layer
multicast (also known as automatic tunneling, where the multicast
would fall back to unicast tunneling if not supporting) which has been
languishing because of a lack of a killer app. This is very close to
decentralized P2P, but its synchronous and would have router support.
The current version of this is AMT - here is a draft

http://www.ietf.org/internet-drafts/draft-ietf-mboned-auto-multicast-03.txt

Regards
Marshall

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From: Florian Weimer <[email-masked]>
Date: Tue, 08 Feb 2005 11:04:43 +0100

> underlying DHT mechanism.

Currently, mDNS is not at all interoperable with existing DNS setups
because of its use of the "local" TLD.