Mobile Node Identifier Types for MIPv6
Extracted elements (16)
Identifiers tied to physical elements of the device (e.g., MAC address) help in deployment of Mobile IP because in many cases they are the most natural means for uniquely identifying the device and avoid additional lookup steps that might be needed if other identifiers were used.
RFID identifier types were originally proposed for inclusion in the main body of the specification but moved to a non-normative appendix due to insufficient support for allocating RFID types at the time, and because RFID-based mobile devices may create privacy exposures unless confidentiality is assured for signaling.
The MN identifier option defined in RFC 4283 previously specified only the MN NAI type; this document extends the option to support additional identifier types used in telecommunications standards (IMSI, P-TMSI, GUTI) and IEEE addressing (EUI-48, EUI-64), enabling interoperability with 3GPP and IEEE-based systems.
Clients and servers MUST treat DUIDs as opaque values and MUST only compare DUIDs for equality.
IPv6 Unique Local Addresses (ULAs) MAY be used as mobile node identifiers as long as any security operations making use of the ULA also take into account the domain in which the ULA is guaranteed to be unique.
The IMSI MUST be encoded as a string of octets in network order where each digit occupies 4 bits, and if needed for full octet size, the last digit MUST be padded with 0xf.
The IPv6 address used as a mobile node identifier MUST be a unicast routable IPv6 address. Multicast addresses, link-local addresses, and the unspecified IPv6 address MUST NOT be used.
Seven new mobile node identifier types are defined for use with the MN identifier option: IPv6 Address (type 2), IMSI (type 3), P-TMSI (type 4), EUI-48 address (type 5), EUI-64 address (type 6), GUTI (type 7), and DUID (type 8). Types 9-15 are reserved and 16-255 are unassigned.
This document assigns values 2-8 in the 'Mobile Node Identifier Option Subtypes' registry (IPv6 Address=2, IMSI=3, P-TMSI=4, EUI-48=5, EUI-64=6, GUTI=7, DUID=8), reserves 9-15, and leaves 16-255 unassigned. The registration procedure is Standards Action.
Mobile node identifiers are considered private information. Packets including the MN identifier extension MUST be encrypted so that no personal information or trackable identifiers are inadvertently disclosed to passive observers. IPsec ESP in transport mode with confidentiality and integrity protection is one applicable mechanism.
Some MN identifiers contain sensitive identifiers that in other SDO protocols are only used for initial network entry signaling, with subsequent exchanges relying on a temporary identifier. Managing the association between long-lived and temporary identifiers is outside the scope of this document.
The DUID (DHCPv6 Unique Identifier) identifier type begins with an initial two-octet type field that distinguishes the various DUID subtypes.
The EUI-48 address identifier is encoded as 6 octets containing the IEEE EUI-48 address.
The EUI-64 address identifier is encoded as 8 octets containing the full IEEE EUI-64 address.
The IMSI identifier is encoded as a string of octets in network order (high to low), where each decimal digit occupies 4 bits. If needed for full octet size, the last digit MUST be padded with 0xf (e.g., IMSI 123456123456789 encodes as 0x12, 0x34, 0x56, 0x12, 0x34, 0x56, 0x78, 0x9f).
The IPv6 Address identifier type is encoded as a 16-octet string containing a full unicast routable IPv6 address assigned to the mobile node.