> On 1/6/2011 9:28 PM, Dan Wing wrote: > >> -----Original Message----- > >> From: Matthew Kaufman [mailto:matt...@matthew.at] > >> Not really. Imagine the case where you're on IPv6 and you can only > >> reach > >> IPv4 via a NAT64, and there's no progress made on the detection > >> problem. > >> And your family member is on a Skype-enabled TV plugged into an > >> IPv4-only ISP. > >> > >> Now you can't get a direct media path between you, even though their > >> ISP > >> is giving them IPv4 and your ISP is *claiming* you can "still reach > the > >> IPv4 Internet". > >> > >> Skype can still make this work by relaying, > > Skype could make it work with direct UDP packets in about 92% of > > cases, per Google's published direct-to-direct statistic at > > http://code.google.com/apis/talk/libjingle/important_concepts.html > > > If one end is behind a NAT64 and there is no mechanism for discovering > the NAT64's IPv6 interface prefix and mapping algorithm (and at present > there is not), there is no way to send IPv6 IP packets from the > IPv6-only host to IPv4 literal addresses (that is to say, addresses > learned via a mechanism other than DNS responses synthesized by the > DNS64 part of the NAT64 "solution") on the IPv4 Internet through said > NAT64. > > That's the case we're discussing here.
There are a bunch of ideas for how to accomplish that. Several of the ideas don't require any support by the network infrastructure, draft-korhonen-behave-nat64-learn-analysis. > It breaks Skype, Adobe's RTMFP, BitTorrent, ICE-based NAT traversal, > etc. Even the protocol described in the referenced document, Jingle (as > it essentially uses ICE) fails. The candidate IPv4 addresses for the > end > that's on the IPv4 Internet (local and STUN-derived) that are delivered > over Jingle's XMPP path cannot be used by the host that is on IPv6 + > NAT64 to reach the IPv4 Internet because it has no IPv4 sockets > available to it and even if it knew that NAT64 existed (which would > take > a modification to the Jingle-based apps) and opened an IPv6 socket it > wouldn't know what IPv6 address to use to reach the IPv4 host because > there's no discovery mechanism. If you want we can take this back to > the BEHAVE list now. Sure. -d > > Matthew Kaufman
