Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Relay Agent Remote-ID Option
Extracted elements (10)
The enterprise-number field is included so that the remote-id namespace is vendor-scoped, allowing different vendors to independently assign remote-id values without coordination, while still achieving global uniqueness via the enterprise-number prefix.
This option is the DHCPv6 equivalent of the DHCPv4 Relay Agent Option's Remote-ID suboption defined in RFC 3046; motivation and usage scenarios are described there.
Each vendor MUST ensure that the remote-id is unique for its enterprise-number, so that the octet sequence of enterprise-number followed by remote-id is globally unique. Including the relay agent's DUID in the remote-id is one way to achieve this.
The DHCPv6 server SHOULD treat the combined enterprise-number and remote-id as an opaque value and apply policies based on exact string match only; the remote-id field SHOULD NOT be internally parsed by the server.
DHCPv6 relay agents may be configured to include a Remote-ID option in relayed RELAY-FORW messages. There is no requirement that a server return this option in a RELAY-REPLY message.
The remote-id field is an opaque, vendor-specific value whose meaning is defined by the enterprise indicated in the enterprise-number field. It may encode caller ID, username, ATM address, modem ID, remote IP, X.25 address, or port identifier.
IANA has assigned DHCPv6 option code 37 for the Relay Agent Remote-ID Option (OPTION_REMOTE_ID).
Even if the DHCP server trusts the relay agent, confidence in the remote-id information is no higher than the relay agent's own confidence in it. Clients may be able to spoof port identifiers, caller ID, or other data carried in this option, so sites should evaluate spoofing risk before relying on it.
Security for DHCPv6 messages between servers and relay agents should follow RFC 3315 section 21.1 (message security) and section 23 (general DHCPv6 security considerations).
The Relay Agent Remote-ID option (OPTION_REMOTE_ID, code 37) contains a 2-octet option-code, 2-octet option-len (minimum 5), a 4-octet enterprise-number (IANA-registered), and a variable-length opaque remote-id field.