I'm recently working on a project, in which we are provided two network one with IPv6 Connectivity only and other with IPv4 Connectivity only.

These two networks are connected to each other with a switch(i.e., Cisco 4503 which also works as router) and our task is that, we have to configure that switch/router in such a way that a IPv4 host can send packet to IPv6 host and vice-verse. I have try all the tunneling, but in all of them IPv6 can only be connected to IPv6 host only not with IPv4.

I need your help in this that how can i made router configuration so that it should be possible to connect two Different Host with different IP versions i.e., one with ipv4 and other with ipv6.


I don't think it's possible at all. You have two people, one talks only french and another talks only swahili, you need to establish communication. You definitely need someone who knows both to translate.

What you need is not tunnels, you need some sort of NAT64, but since one network is ONLY 4 and another is ONLY 6, you have nowhere to place it but on the router itself. I have no idea if your router supports NAT64.


The Cisco feature you want for this is called NAT-PT. I'm not sure if your particular switch supports it - check that out with the Cisco feature explorer. (Try to get the latest code you can on your switch.)

Cisco's NAT-PT documentation is here,



You need at least one device that can talk both IPv4 and IPv6 to do the protocol translation for you. You can do this at layer-2 (NAT64: http://en.wikipedia.org/wiki/NAT64, NAT-PT is deprecated) or at layer-3 (proxy).

Once you have this in place you need to think about how to tell the device that initiates the connection which address to connect to. If the IPv4 host initiates the connection it needs an IPv4 address to connect to, and if the IPv6 host initiates the connection then it needs an IPv6 address to connect to. They will only be able to talk to IP addresses that correspond to their own version.

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