Symptom

*** Dynamic NAT64 not working in IOS *** HW: ISR 3925 with C3900-SPE100/K9 3925-959#sh nat64 sta NAT64 Statistics Number of NAT64 enabled interfaces: 2 Number of packets translated by stateless NAT64: Packets translated (IPv4 -> IPv6): 0 Packets translated (IPv6 -> IPv4): 0 Number of packets translated by stateful NAT64: Packets translated (IPv4 -> IPv6): 0 <------- Return traffic is coming on the Ipv4 interface but the 4 to 6 translation is not happening. Packets translated (IPv6 -> IPv4): 45 <--------- 6to4 working fine. ======================================================================================================================= Summary : In the Debugs, we can see the 6to4 translation happening and we can see the the IPv4 packets on the IPv4 only host. The issue is that we cannot see the return 4to6 translation going on the NAT64 router. =======================================================================================================================

Conditions

Dynamic NAT64 on IOS. Traffic initiated from IPv6 only host is translated to IPv4. Return traffic is being dropped when received on the NAT64 router.

Workaround

Further Problem Description