Proxy Mobile IPv6
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Extracted elements (28)
Mobile IPv6 sequence numbers are insufficient for PMIPv6 because a newly serving MAG cannot determine the last sequence number used by the previous MAG in the absence of context transfer. PMIPv6 therefore supports a Timestamp-based alternative for message ordering when sequence numbers cannot be maintained across handoffs.
PMIPv6 is built on top of Mobile IPv6 to reuse home agent functionality and well-tested signaling message formats, enabling a common home agent to serve both host-based MIPv6 and network-based PMIPv6 mobile nodes without requiring a separate new anchor infrastructure.
This specification supports only the Per-MN-Prefix model and explicitly does not support the Shared-Prefix model. Home network prefixes assigned to a mobile node are for that node's exclusive use, ensuring unambiguous routing and binding cache lookups across the PMIPv6 domain.
PMIPv6 signaling messages do not carry the Home Address destination option or the Type 2 Routing header (unlike standard MIPv6), so IPsec SPD selectors require no special considerations for those headers.
The mobile node is not required to participate in any IP mobility-related signaling within a PMIPv6 domain. The network tracks the mobile node's movements and initiates all mobility signaling on its behalf, making the mobile node's IPv6 stack mobility-agnostic.
For multihomed mobile nodes, the LMA MUST allocate a separate mobility session and Binding Cache entry (with its own lifetime) for each attached interface. All prefixes assigned to a given interface MUST be managed under exactly one mobility session.
If the Home Network Prefix option, Handoff Indicator option, or Access Technology Type option is absent from the PBU, the LMA MUST reject the request with the corresponding status code (MISSING_HOME_NETWORK_PREFIX_OPTION, MISSING_HANDOFF_INDICATOR_OPTION, or MISSING_ACCESS_TECH_TYPE_OPTION).
IKEv2 SHOULD be used to set up security associations between the MAG and LMA to protect Proxy Binding Update and Proxy Binding Acknowledgement messages.
IPsec ESP in transport mode with mandatory integrity protection SHOULD be used for protecting PMIPv6 signaling messages. Confidentiality protection of signaling messages is not required.
The LMA MUST apply BCE lookup rules in strict order (prefix match, then link-layer identifier match, then MN-Identifier-only match) to correctly distinguish new mobility session creation from updates to existing sessions in multihomed scenarios.
The LMA MUST identify the mobile node from the Mobile Node Identifier option in the PBU. If the option is absent, the LMA MUST reject the request with status MISSING_MN_IDENTIFIER_OPTION.
The LMA MUST restrict the creation and manipulation of proxy bindings to specifically authorized MAGs and prefixes, and MUST be locally configurable to authorize such specific MAG-prefix combinations to prevent unauthorized binding creation.
The Timestamp-based ordering scheme SHOULD NOT be used if the clock skew on any neighboring MAG (relative to the common time source) exceeds half the reconnection time, as it will not predictably work in all cases.
Upon accepting a de-registration PBU (lifetime=0), the LMA MUST wait MinDelayBeforeBCEDelete time before deleting the BCE to allow a new MAG time to register. During the wait, the LMA SHOULD drop the mobile node's data traffic.
When a PBU arrives from a new MAG after handoff, the LMA MUST update the BCE, remove previous prefix routes, delete the tunnel to the previous MAG if no other MNs share it (SHOULD), establish a tunnel to the new MAG if none exists, and create new prefix routes over the new tunnel.
When sending the PBA, the LMA MUST NOT include the Type 2 Routing header in the IPv6 header, unlike in standard Mobile IPv6. The source address MUST be the LMAA and the destination MUST be the Proxy-CoA of the requesting MAG.
When the sequence-number-based scheme is used, the serving MAG MUST have the ability to obtain the last sequence number sent for that mobility session. The sequence number MUST be maintained on a per-mobility-session basis and MUST be available to the serving MAG.
The Access Technology Type option carries the radio/link access technology by which the mobile node is currently attached (e.g., virtual, 3GPP GERAN, 3GPP UTRAN, 3GPP E-UTRAN, 3GPP2, WiMAX, nomadic). This option is mandatory in both PBU and PBA.
The Binding Cache Entry at the LMA is extended with: a proxy-registration flag, MN-Identifier, MN link-layer identifier, MAG link-local address on the point-to-point link, list of assigned home network prefixes with lengths, tunnel interface identifier, access technology type, and a 64-bit timestamp of the most recently accepted PBU.
The Handoff Indicator option encodes the reason for a PBU: 1=attachment of a new mobile node, 2=handoff between two different interfaces of the MN, 3=handoff between MAGs for the same interface, 4=handoff state unknown, 5=handoff state not changed (for binding lifetime extension).
The Link-local Address option carries the link-local address of the MAG on the point-to-point link shared with the mobile node. If ALL_ZERO is sent in the PBU, the LMA generates the link-local address and returns it in the PBA for the MAG to use on the access link.
The Mobile Node Link-layer Identifier option carries the link-layer identifier of the mobile node's attached interface. An ALL_ZERO value is explicitly prohibited as a valid identifier and cannot be used as an interface identifier.
The Proxy Binding Acknowledgement message MUST include Mobile Node Identifier, at least one Home Network Prefix, Handoff Indicator, and Access Technology Type options. Timestamp, Link-layer Identifier, and Link-local Address options MUST be present if and only if they were present in the corresponding PBU.
The Proxy Binding Update is a Binding Update message (from MIPv6) with the (P) flag set to 1. It is sent from the MAG to the LMA's LMAA address and MUST carry the Mobile Node Identifier, Home Network Prefix, Handoff Indicator, and Access Technology Type options.
The Timestamp option carries a 64-bit timestamp (in NTP format) inserted by the MAG for message ordering at the LMA. The LMA accepts a PBU only if its timestamp is strictly greater than the most recently accepted timestamp for that mobility session.
RFC 5213 registers new Mobility Header option types (Home Network Prefix Option, Handoff Indicator Option, Access Technology Type Option, Mobile Node Link-layer Identifier Option, Link-local Address Option, Timestamp Option), new PBA status code values, and the (P) flag in the Binding Update message.
Proxy Binding Update and Proxy Binding Acknowledgement messages MUST be protected using end-to-end security associations offering integrity and data origin authentication. Both MAG and LMA MUST implement IPsec as a mandatory-to-implement security mechanism.
A PMIPv6 mobility session transitions through: (1) New Session — initial PBU triggers BCE creation and tunnel/prefix-route setup; (2) Lifetime Extension No Handoff — same MAG refreshes binding; (3) Lifetime Extension After Handoff — new MAG updates BCE, old routes removed, new tunnel and routes created; (4) De-Registration — lifetime=0 PBU starts MinDelayBeforeBCEDelete timer, then BCE deleted.