Hello Marc,   
      
   On Tuesday November 02 2010 12:56, you wrote to me:   
      
    MvdV>> Of course it won't last forever. Nothing is forever. But I   
    MvdV>> think it will last at least another five years. Long enough to   
    MvdV>> be affected by the IPv4 address depletion.   
      
    MvdV>> Then again: I am notorious for my bad predictions...   
      
    ML> There is one thing that strikes me here in relation to IPv6.  The WAN   
    ML> may be someday soon obligated to run v6 more heavily than now, but if   
    ML> your system is behind a v6 router, the NAT in the router most probably   
    ML> will be able to run the LAN side of things in traditional v4 format.   
      
   That is what I thought too at first, but when I delved into the matter I found   
   out that it won't work that way. here is an interesting article from a Ducth   
   ex-fidonetter who wrote about making Ipv4 talk to Ipv6 and vice versa:   
   http://tinyurl.com/2efvauf   
      
    ML> As far as FidoNet is concerned, even with v6 in place, if the domain   
    ML> has a registered domain name (even a dynamic one like dyndns.org), v6   
    ML> should make no difference to programs like IRex, where all you have to   
    ML> do is point a BinkP connection to a domain name rather than a full v6   
    ML> address.  Let the ISP's DNS resolver take care of the rest... or so it   
    ML> would seem to me.   
      
   That is not how it works. applications that talk to each other over the   
   internet do so using the IP numbers. Just like telephones connecting to each   
   others do so by using the telephone numbers.   
      
   when a host is addressed by name, the application wanting to talk to it, first   
   looks up its number in the "internet telephone book". It does so by contacting   
   the nearest DSN server. The DNS server eventually returns the IO address. With   
   or without consukting DNS servers higher up in the chain. Onlly when the   
   calling application has the IP number of the destination does it attempt to   
   establish contact.   
      
   With the introduction of IPv6, the DNS query may return an IPv4 or an IPv6   
   number, or both.   
      
   Now suppose your ISP only gives you an IPv6 address. Suppose I too have only   
   an IPv6 address for my binkp compatible mailer. How is your Irex going to   
   contact it?   
      
   Your Irex has a IPv4 address on the local WAN. An address in the private   
   range. In order to make a call to my binkp server, it needs my IP address.   
   Irex only knows IPv4 addresses. My binkp server does not have a public IPv4   
   address. So a DNS query for its IPv4 address will return an "unknown host"   
   error. You could tell Irex that my address is 192.168.1.100. (Which is the   
   address on my LAN.) Bit how will this ever work? Even if you have that   
   hypothetical router that NATs IPv6 into IPv4, how is it going to translate   
   192.168.1.100 into my IPv6 address?   
      
   Just like people are now tunneling IPv6 over IPv4, one can tunnel IPv4 over   
   IPv6, but for that one needs a public IPv4 address, which you do not have.   
      
    ML> Main thing is for ones system to be behind a NAT equipped   
    ML> router/modem.   
      
   No, that does not work. If you no longer have a public IPv4 address, you need   
   an IPv6 capable binkp implementation.   
      
      
   Cheers, Michiel   
      
   --- GoldED+/W32-MINGW 1.1.5-b20070503   
    * Origin: http://www.vlist.org (2:280/5555)