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11. Selecting Addresses for Assignment to an IA

11. Selecting Addresses for Assignment to an IA​

A server selects addresses to assign to an IA based on the address assignment policy determined by the server administrator and specific information about the client determined by the server from some combination of the following sources:

  • The link to which the client is attached. The server determines the link as follows:

    • If the server receives the message directly from the client and the source address in the IP datagram in which the message was received is a link-local address, the client is on the same link as the interface on which the message was received.

    • If the server receives the message from a forwarding relay agent, the client is on the same link as the interface identified by the link-address field in the relay agent message.

    • If the server receives the message directly from the client and the source address in the IP datagram in which the message was received is not a link-local address, the client is on the link identified by the source address in the IP datagram (note that this situation will only occur if the server has enabled the client to use unicast message delivery and the client has sent a message that allows unicast delivery).

  • The DUID provided by the client.

  • Other information in options provided by the client.

  • Other information in options provided by the relay agent.

Any address assigned by the server that is based on an EUI-64 identifier MUST contain an interface identifier with the "u" (universal/local) and "g" (individual/group) bits of the interface identifier set appropriately, as shown in section 2.5.1 of RFC 2373 [RFC 2373].

A server MUST NOT assign addresses that are reserved for other purposes. For example, a server MUST NOT assign reserved anycast addresses from any subnet, as defined in RFC 2526.

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