terface and we can also see the IPv6 stack initiating the procedures that are needed when a new address is configured, such as joining an appropriate Solicited-Node Multicast group and issuing a DAD procedure (packet #49). As there is no answer to the DAD originated Neighbor Solicitation the stack starts using the address. However, we still have the existing Destination Cache entry pointing at fe80 : 1, which is now also used by the UE. Nothing gets through over the link as all packets destined to 2001: 6e8 : 2100 100 : 30 are sent to a local interface, which then fails to handle them in any way, and packets are just silently discarded (this is probably due the fact that the Neighbor Cache incorrectly points to the wrong link-layer address and the IP stack gets confused). Finally, at the packet #62 we remove fe80 : 1 from the UE interface, after which the UE IPv6 stack immediately does an address resolution for the GGSN link-local address fe80 : 1 and once the neighbor-cache is updated user plane packets start flowing again as normal (starting from the packet #65). Deploying IPv6 in 3GPP Networks Source Destination Protocol 1702113 Advertisement 7 5.078778 ff02::1:ffc9:35c4 ICMPv6 Neighbor Solicitation for 2001:6e8:2100:198:6 8 5.090830 fe80::6b:85ff:fec9:35c4 ff02:12 ICMPv6 Multicast Listener Done 9 5.090931 fe80::6b:85ff:fec9:35c4 ff02:1fb ICMPv6 Multicast Listener Report 10 5.108896 fe80::1 ff02::1 ICMPv6 Router Advertisement 18 8.973834 fe80::6b:85ff:fec9:35c4 ff02::fb ICMPv6 Multicast Listener Report 34 15.191912 fe80::6b:85ff:fec9:35c4 fe80:11 ICMPv6 Neighbor Solicitation for fe80::1 from 02:6b 35 15.195259 fe80:11 fe80::6b:85ff:fec9:35c4 ICMPv6 Neighbor Advertisement fe80:11 (rtr. sol, OVI 41 28.269187 (001:6e8:2100:198:6b:85ff:fe 2001:6e8:2100:100::30 ICMPv6 Echo (ping) request id=0x1cd4 seq=0 42 28.558916 2001:6e8:2100:100::30 2001:6e8:2100:198:6b:85ff:fec9:35c4 ICMPv6 Echo (ping) reply id=0x1cd4 seq=0 43 29.269349 001:6e8:2100:198:6b:85ff:fec9:35c4 2001:6e8:2100:100::30 ICMPv6 Echo (ping) request id=0x1