This article explains the behavior when a DHCPv6 renew packet is received for a subscriber that has been terminated manually in case of a DHCP relay proxy.
MX doesn’t respond to the second renew packet (for a single subscriber) when IA_NA is configured for the WAN IPv6 address and IA_PD is configured for prefix delegation for the LAN ranges.
Assumption: IA_NA is used for the WAN IPv6 address, and IA_PD is used for prefix delegation for the LAN ranges.
If a DHCPv6 renewal arrives while there is no related subscriber session, only the DHCPv6 prefix corresponding to the renewal that comes first (IA_NA or IA_PD) will be installed related to the subscriber session. Subsequent renewals are discarded and that prefix is not added to the subscriber session state.
This is expected behavior that if the IA_NA is used for reachability, the IA_PD is orphaned when the NA is gone. For the current versions of jdhcpd , the addresses are associated with a single session, and there is no support for adding addresses independently.
jdhcpd
Recommendation: It’s a good idea to keep the two lease lifetimes equivalent for IA_NA and IA_PD on external DHCP servers. Also the “no-bind-on-request” knob can be set on the MX to minimize the possible split of the NA & PD options.