An attachment method for Identification-Location Split, ID-Loc-Split in an Next Generation Network, NGN, comprising: performing a network attachment process for a User Terminal, UE through an ID-Loc-Split Mapping Function Entity, ILSM-FE, wherein a user identification, Host ID, is used during an authentication and authorization process, the method specifically comprising: A: performing authentication and authorization to a user identity through the ILSM-FE during the authentication and authorization process; B: assigning an IP address to the user terminal through an IP address configuration process; and C: when location of a user changes, a) the UE or a Transport Location Management Functional Entity, TLM-FE, sends a request for user identification to location, ID/LOC mapping, and b) the ILSM-FE responds to the request, and performing a mapping between the Host ID and the IP address by the ILSM-FE; characterized in that when the UE is in mobility or multihoming scenario, the mapping between the Host ID and the IP address in a database of the ILSM-FE is one-to-multiple, wherein in step C, initiating (Step 421) the ID/LOC mapping request to the ILSM-FE by the user terminal, wherein the request includes a new IP address of the user; and transmitting (Step 422) a result of mapping from the ILSM-FE to the user terminal after the ILSM-FE performs the mapping between the Host ID and the IP address; or firstly initiating (Step 521) the ID/LOC mapping request to a TLM-FE by the user terminal, wherein the request includes a new IP address of the user; and forwarding (Step 522) the ID/LOC mapping request from the TLM-FE to the ILSM-FE; and after the ILSM-FE performs the mapping between the Host ID and the IP address, transmitting a result of mapping to the user terminal through the ILSM-FE; or initiating the ID/LOC mapping request to the ILSM-FE by the TLM-FE, wherein the request includes a new IP address of the user; transmitting an ID/LOC mapping response from the ILSM-FE to the TLM-FE after the ILSM-FE performs the mapping between the Host ID and the IP address. performing a network attachment process for a User Terminal, UE through an ID-Loc-Split Mapping Function Entity, ILSM-FE, wherein a user identification, Host ID, is used during an authentication and authorization process, the method specifically comprising: A: performing authentication and authorization to a user identity through the ILSM-FE during the authentication and authorization process; B: assigning an IP address to the user terminal through an IP address configuration process; and C: when location of a user changes, a) the UE or a Transport Location Management Functional Entity, TLM-FE, sends a request for user identification to location, ID/LOC mapping, and b) the ILSM-FE responds to the request, and performing a mapping between the Host ID and the IP address by the ILSM-FE; A: performing authentication and authorization to a user identity through the ILSM-FE during the authentication and authorization process; B: assigning an IP address to the user terminal through an IP address configuration process; and C: when location of a user changes, a) the UE or a Transport Location Management Functional Entity, TLM-FE, sends a request for user identification to location, ID/LOC mapping, and b) the ILSM-FE responds to the request, and performing a mapping between the Host ID and the IP address by the ILSM-FE; a) the UE or a Transport Location Management Functional Entity, TLM-FE, sends a request for user identification to location, ID/LOC mapping, and b) the ILSM-FE responds to the request, and performing a mapping between the Host ID and the IP address by the ILSM-FE;