[Info-vax] implementing IPv6 on the internet

[David Froble]

Dirk Munk wrote:
> Chris wrote:
>> On 09/23/16 21:22, Dirk Munk wrote:
>>
>>>
>>> And now we get a problem. How is the router suppose to know it has to
>>> build a new IPv6 packet with the same payload, but destination address
>>> X6, and sending address WAN6?
>>
>> The router will already have it's own V6 address, supplied by the isp.
>> It will also know about the V4 addresses on it's own private subnet
>> and how to work NAT for those addresses.
> 
> Great, and how does the router know the IPv6 address of Microsoft, or 
> even better, how does the router know it has to send the packet to the 
> IPv6 address of Microsoft?
> 
> The PC did a nslookup remember, the router didn't. The router doesn't 
> know it has to exchange the IPv4 address of microsoft by the IPv6 
> address, how could it? If the PC sends something to an IPv4 address, how 
> can the router know if this destination also has an IPv6 address?

In your own words:

2. it will get the IPv4 address X4 (and the IPv6 address X6) of microsoft.com

So, the PC, or whatever, knows both addresses.  If the PC sent out the packet 
with both addresses, then the router could decide which it wants to use.  WOuld 
be a change in the PC software, but, that happens every day.