Re: [Int-area] Revving draft-intarea-shared-addressing-issues

> -----Original Message-----
> From: Bernard Aboba [mailto:bernard_aboba@hotmail.com] 
> Sent: Monday, June 14, 2010 1:05 PM
> To: dthaler@microsoft.com; dwing@cisco.com; ford@isoc.org
> Cc: int-area@ietf.org; brian.e.carpenter@gmail.com; 
> draft-ford-shared-addressing-issues@tools.ietf.org; lorenzo@google.com
> Subject: RE: [Int-area] Revving draft-intarea-shared-addressing-issues
> 
> The NAT box can use its public IPv4 address to enable 6to4, 
> thereby providing IPv6 support for hosts "behind" it.  Why 
> would this result in a disconnected IPv6 island?

Diagram of what I understand the problem to be with 6to4
behind another NAT:

  IPv6 host--+
              \
               +---[home NAT]----[Carrier's NAT]---[Internet]
              /      ^       ^                  ^
  IPv6 host--+       ^       ^                  ^
                     ^       ^             IP address sharing
                     ^       ^             with multiple 
                     ^       ^             subscribers
                     ^       ^
                     ^     the in-home NAT's WAN address 
                     ^     is not publicly routable
                     ^
                     ^
               this in-home 
             NAT turns on 6to4

-d

> > From: dthaler@microsoft.com
> > To: dwing@cisco.com; ford@isoc.org
> > Date: Mon, 14 Jun 2010 19:04:31 +0000
> > CC: int-area@ietf.org; brian.e.carpenter@gmail.com; 
> draft-ford-shared-addressing-issues@tools.ietf.org; lorenzo@google.com
> > Subject: Re: [Int-area] Revving 
> draft-intarea-shared-addressing-issues
> > 
> > > Some routers enable 6to4 [RFC3056] on their WAN link. 
> 6to4 requires a
> > > publicly-routable IPv4 address. Enabling 6to4 behind a 
> NAT causes a
> > > disconnected IPv6 island."
> > 
> > The last sentence above is incorrect. The second sentence 
> is correct.
> > So one cannot "enable" 6to4 behind a NAT since one has no 
> > publically-routable IPv4 address. Hence one does not get an IPv6
> > island. One gets no IPv6 at all (from 6to4 anyway).
> > 
> > -Dave
> > 
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> 
> 