Mobile Access Gateway Configuration Parameters Controlled by the Local Mobility Anchor
Extracted elements (20)
The LMA-controlled configuration extension addresses the operational challenge of managing tens of thousands of MAGs in large PMIPv6 deployments (e.g., residential), where aggressive local timer configurations can create unpredictable and excessive signaling load on the LMA. Centralizing control at the LMA provides deterministic load management.
The LCMPInitialRetransmissionTime and LCMPMaximumRetransmissionTime variables correspond directly to INITIAL_BINDACK_TIMEOUT and MAX_BINDACK_TIMEOUT from RFC 5213 Section 6.9.4, and LCMPHeartbeatInterval and LCMPHeartbeatMaxRetransmissions MAY be derived from HEARTBEAT_INTERVAL and MISSING_HEARTBEATS_ALLOWED in RFC 5847 if those are configured on the LMA.
If the LCMP mobility option contains the Heartbeat Control Sub-Option, the MAG MUST overwrite its local heartbeat timer parameters with the received values. If any parameter except HB-Retransmission-Delay is ZERO, the PBA MUST be ignored and an error SHOULD be logged.
If the PBA received from the LMA contains the LCMP option with the Binding Re-registration Control Sub-Option, the MAG MUST overwrite its locally configured re-registration timer parameters with the received values. If any parameter in the sub-option is ZERO, the MAG MUST ignore the PBA and SHOULD log an error.
On receiving a PBU, if EnableLCMPSubOptHeartbeatControl is set and all heartbeat variables are NON_ZERO, the LMA MUST include the Heartbeat Control Sub-Option in the PBA. If any heartbeat variable is ZERO, the LMA MUST reject the binding with status code '128 - Reason Unspecified'.
On receiving a PBU, if EnableLCMPSubOptReregControl is set and all three re-registration timer variables are NON_ZERO, the LMA MUST include the Binding Re-registration Control Sub-Option in the PBA. If any of the three variables is ZERO, the LMA MUST reject the binding with status code '128 - Reason Unspecified'.
The configured values for LMA protocol configuration variables (EnableLCMPSubOptReregControl, EnableLCMPSubOptHeartbeatControl, and associated timer variables) MUST survive server reboots and service restarts.
The LCMP option MUST NOT appear more than once in a given PBA message, and it MUST contain one or more LCMP sub-options.
The LCMPHeartbeatInterval SHOULD NOT be less than 30 seconds or more than 3600 seconds. The LCMPHeartbeatRetransmissionDelay SHOULD be less than LCMPHeartbeatInterval.
Both the LMA Binding Cache Entry and the MAG Binding Update List data structures (as defined in RFC 5213) must be extended to store the six LCMP-related configuration parameters received via the LCMP option.
LMA configuration variables (LCMPReregistrationStartTime default 10 units of 4s, LCMPInitialRetransmissionTime default 1s, LCMPMaximumRetransmissionTime default 32s, LCMPHeartbeatInterval default 60s, LCMPHeartbeatRetransmissionDelay default 5s, LCMPHeartbeatMaxRetransmissions default 3) MAY be configured at various granularities but the LMA MUST be able to determine values per individual binding.
The LCMP option is a mobility header option carried exclusively in Proxy Binding Acknowledge (PBA) messages, used by the LMA to signal configuration parameters (re-registration and heartbeat timers) to the MAG.
Two LMA configuration flags control sub-option inclusion: EnableLCMPSubOptReregControl (default 0, disabled) governs the Binding Re-registration Control Sub-Option, and EnableLCMPSubOptHeartbeatControl (default 0, disabled) governs the Heartbeat Control Sub-Option.
IANA assigned type value 62 to the new 'LMA-Controlled MAG Parameters' mobility header option in the 'Mobility Options' registry (RFC 6275).
IANA created a new 'LMA-Controlled MAG Parameters Sub-Option Type Values' registry with three initial values: 0=Reserved, 1=Binding Re-registration Control Sub-Option, 2=Heartbeat Control Sub-Option. New values require Expert Review (RFC 8126).
The LCMP option is carried like any other mobility header option in Proxy Binding Update and Acknowledgement messages and does not require special security considerations beyond those already defined for PMIPv6 signaling.
Each LCMP sub-option has an LCMP Type field (1 octet), LCMP Length field (1 octet), and variable Sub-Option Data. Sub-options have an alignment requirement of 4n. Defined types: 0=Reserved, 1=Binding Re-registration Control, 2=Heartbeat Control.
The Binding Re-registration Control Sub-Option (LCMP Type=1, LCMP Length=6) contains three 16-bit unsigned integer fields: Re-registration-Start-Time (in 4-second units), Initial-Retransmission-Time (seconds), and Maximum-Retransmission-Time (seconds).
The Heartbeat Control Sub-Option (LCMP Type=2, LCMP Length=6) contains three 16-bit unsigned integer fields: HB-Interval (seconds after a successful heartbeat exchange), HB-Retransmission-Delay (minimum seconds before retransmission), and HB-Max-Retransmissions (maximum retransmission count).
The LMA-Controlled MAG Parameters (LCMP) option has a Type field (1 octet, value 62), a Length field (1 octet, excluding Type and Length), and a variable-length LCMP Sub-Option(s) field. The option has an alignment requirement of 4n+2.