Re: question about draft-durand-v6ops-natv4v6v4-00

[james woodyatt <jhw@apple.com>]

On Nov 19, 2007, at 01:15, Iljitsch van Beijnum wrote:
> On 18 nov 2007, at 20:32, marcelo bagnulo braun wrote:
> > Do you think that current nat traversal techniques would not work  
> > properly if multiple levels of nats need to b traversed?
>
> As far as I've been able to deduce, uPnP and NAT-PMP (not IETF  
> work) that are common in consumer CPEs won't work unless there is  
> one NAT and it's on the local LAN. I could be wrong, though.

This is correct.  I know of at least one real application that works  
through one layer of NAT, but not two: the Back To My Mac feature in  
Mac OS X 10.5, which relies on registering wide-area DNS-SD service  
advertisements in the members.mac.com zone for the tunnel endpoints.   
The mDNSResponder agent doesn't manage the UNSAF problem when there  
are multiple levels of NAT between the Mac OS X host and the DNS  
servers.

BTMM can use either NAT-PMP or UPnP IGD.  No other mechanisms are  
supported.


--
james woodyatt <jhw@apple.com>
member of technical staff, communications engineering