Need to communicate across different Address Types?

Do you have ipv4 only servers which you need to connect from ipv6 clients or viceversa?

Portproxy is the solution. It acts like a proxy between ipv4 and ipv6 applications, forwarding requests based on the ipaddress and port.

You can configure the proxy to forward  requests received on one / any of ipv6/ipv4 address,A port X to ipv6/ ipv4 address  B at port Y. The cool part is that addresses A and B can belong to same machine or they can be in different machines. Eventhough there is no server listening on ipv6 addresses at port 80, we can still fake the server by configuring the portproxy and can connect to the server from an ipv6 client.

for example i can configure to automatically forward

1.  ipv6 port 80 to ipv4 port 80.
2. ipv6 port 80 on machine A to ipv4 address port 80 on machine B.

netsh interface portproxy>add v6tov4 listenport=80 connectaddress=x.x.x.x connectport=80

netsh interface portproxy>show v6tov4

Listen on IPv6: Connect to IPv4:

Address Port Address Port
--------------- ---------- --------------- ----------
* 80 x.x.x.x 80

Depending on the connectaddress, the requests are forwarded to the same machine or to a different machine. If no connectaddress is specified, localhost is used.

The other cool thing is this feature is already present in windows 20003 machine.. All you have to do is just configure it to automatically forward.