Subject: [MMUSIC] IPv4 and IPv6 interworking

From: "Dan Wing" <[email-masked]>
Date: Mon, 29 Sep 2003 13:14:40 -0700

Let's say a Alice capable of sourcing/sinking both IPv4 and IPv6, and Alice
wants to establish a session with Bob.  Alice doesn't know, a priori, if Bob
supports IPv4 or IPv6.  Let's also say that Bob only supports IPv4.

Does Alice have to send an Offer with IPv6, have Bob reject the Offer, and
then Alice has to send another Offer for IPv4?

RFC3266 describes SDP for IPv6, but it appears it isn't possible to
simultaneously offer both IPv4 and IPv6 in SDP.

-d

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From: "James M. Polk" <[email-masked]>
Date: Mon, 29 Sep 2003 17:55:39 -0500

>supports IPv4 or IPv6.  Let's also say that Bob only supports IPv4.

What's the normal response of an IPv4 device that receives an IPv6 packet? 
This seems like a good place to start...

>simultaneously offer both IPv4 and IPv6 in SDP.

cheers,
James

                                *******************
                 Truth is not to be argued... it is to be presented

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From: "Dan Wing" <[email-masked]>
Date: Mon, 29 Sep 2003 20:28:53 -0700

> This seems like a good place to start...

Yes, but it didn't receive an IPv6 packet -- it receives a SIP 
packet from its IPv4-only SIP proxy, but the SDP describes an 
IPv6 session.

The normal reaction to an SDP session you can't support is well
understood.  I'm asking if that's all folks expect out of IPv4/
IPv6 interworking.

-d

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From: "NAKAMURA, Hidefumi" <[email-masked]>
Date: Tue, 30 Sep 2003 13:43:35 +0900

Hi.

If you establish a session with SIP, I think RFC3312 mechanism may help
to solve this problem though some extension will be needed.
(and also in case that the SIP messages are exchanged in IPv4 packets)

RFC3312 describes how to negotiate SDPs between two endpoints without
sending independent INVITE messages twice though it is for the QoS
negotiation.

-- 
NAKAMURA, Hidefumi 
NTT ServiceIntegration /NetworkServiceSystems Labs.
tel: +81(422)59 3904; fax:+81(422)60 4012
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From: Jonathan Rosenberg <[email-masked]>
Date: Tue, 30 Sep 2003 02:54:34 -0400

The right way to do this is with the alt mechanism:
http://www.ietf.org/internet-drafts/draft-camarillo-mmusic-alt-01.txt

in concert with ICE:
http://www.ietf.org/internet-drafts/draft-rosenberg-sipping-ice-01.txt

THe alt mechanism allows Alice to tell Bob about both the v4 and v6 
addresses, and the ICE mechanism (which will be revised as an mmusic 
work item per the last ietf meeting) allows for connectivity in more 
complex cases than the one you describe below. In particular, when 
Alice is v6 only and there is a 6to4 nat.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                600 Lanidex Plaza
Chief Technology Officer                    Parsippany, NJ 07054-2711
dynamicsoft
[email-masked]                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
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From: Magnus Westerlund <[email-masked]>
Date: Tue, 30 Sep 2003 09:03:54 +0200

Hi,

For part of the solution see:
http://www.ietf.org/internet-drafts/draft-camarillo-mmusic-alt-01.txt

This allows one to express that two media blocks are alternative to each 
other, that simply the connection address are variants so that both IPv4 
and a IPv6 address can be offered.

SDP-NG will (I assume) have full support to express transport alternatives.

When it comes to RTSP I think the same mechanism can be used. One will 
however need to use destination in Transport header with the intended 
address to indicate what address family the server should send to. To 
have IPv6 support in destination one will need the specification updates.

Cheers

Magnus

NAKAMURA, Hidefumi wrote:

>>>>Does Alice have to send an Offer with IPv6, have Bob reject the 
>>>
>>>Offer, and
>>>

-- 

Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVA/A
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