scope:

This Recommendation defines the protocol for the M9 interface between the mobile location management physical entity as proxy (MLM-PE(P)) and the MLM-PE as the central instance (MLM-PE(C)) specified in [ITU-T Y.2018].

The M9 reference point provides the information flows to register and update mobility location information in both host-based and network-based mobility cases specified in [ITU-T Y.2018]. In the network-based mobility case, the MLM-PE(P) sends the location registration and/or update request to the MLM-PE(C). In the host-based mobility case, the user equipment (UE) sends the location registration and/or update request to the MLM-PE(P), which will forward it to the MLM-PE(C). The M9 reference point also provides the information flows for retrieving the binding location information regarding UE's reachability. The MLM-PE(P) holds the binding information between mobile user ID (or persistent address) and temporary address (or lower tunnel end point address). The MLM-PE(C) holds the binding information between mobile user ID (or persistent address), and address of the MLM-PE(P). The MLM-PE(P) may identify the corresponding MLM-PE(C) by extracting the home domain from the mobile user ID. The MLM-PE(P) may initiate route optimization through this interface.