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duplicate-clients (DHCPv6 Local Server and Relay Agent)


Hierarchy Level


Specify the criteria that the jdhcpd process uses to support duplicate clients. The router uses the additional criteria to distinguish between the duplicate clients.

Duplicate clients have the same DUID (DHCP unique identifier). Typically, the router treats a request from a duplicate client as a renegotiation, and replaces the existing client entry with a new entry. However, in some cases, the duplicate request is from a different client, and replacement is not desired. When you enable duplicate client support, the router uses the additional criteria to distinguish between the two clients, and grants a lease to the new client while retaining the original client entry.


The only supported differentiating criterion is incoming-interface.

Best Practice:

To allow duplicate clients over the incoming interface for DHCPv6 relay, you must configure the relay-agent-interface-id statement to cause the DHCP relay agent to insert the DHCPv6 Interface-ID option (option 18) in DHCPv6 packets destined for the DHCPv6 server.

Do not configure the use-interface-description statement, because option 18 must include the interface name rather than an interface description.


We recommend that you do not enable or disable duplicate client support mode when clients are bound, because different client keys are used to store the clients in the database depending on the mode. Changing the mode removes clients from the database and then adds them back with a different key.

Additionally, disabling duplicate client support mode causes all duplicate clients to be deleted.



Allow duplicate clients when the incoming DHCPv6 requests are received over different underlying interfaces.

Required Privilege Level

system—To view this statement in the configuration.

system-control—To add this statement to the configuration.

Release Information

Statement introduced in Junos OS Release 16.1.