A method of interface registration for a network device to join in a cluster system, the cluster system being made up of multiple physically independent and interconnected network devices (R1, R2, R3, A, B), characterized in that the cluster system comprises a cluster main device (R1, B), a main control board on the cluster main device being a cluster main control board, the method comprising: when the network device joins in the cluster system, a local interconnection board of the network device sending its local board number to a local main control board of the network device, a local non-interconnection board of the network device receiving the local board number of the local interconnection board sent by the local main control board of the network device and using the local board number of the local interconnection board as a communication agent board number, wherein the local non-interconnection board of the network device communicates with other network devices within the cluster system via the local interconnection board based on the communication agent board number, wherein the local interconnection board is a line card on which interfaces for interconnecting the network device to network devices in the cluster system are located; after a cluster interface registration of the local non-interconnection board and local interconnection board on the cluster main control board, each of the local non-interconnection board and the local interconnection board receiving and storing a mapping relationship between local interface information of the network device and global interface information of the network device sent by the cluster main control board, wherein the local interface information of the network device comprises local interface information of all local line cards of the network device, the local interface information comprises serial number and local board number of each line card of the network device, the serial number comprising frame number of the network device and local board number of corresponding line card, the global interface information of the network device comprises a global board number of each line card of the network device, wherein the mapping relationship between local interface information of the network device and global interface information of the network device sent by the cluster main control board comprises the serial number, the local board number, and the global board number of each line card of the network device. when the network device joins in the cluster system, a local interconnection board of the network device sending its local board number to a local main control board of the network device, a local non-interconnection board of the network device receiving the local board number of the local interconnection board sent by the local main control board of the network device and using the local board number of the local interconnection board as a communication agent board number, wherein the local non-interconnection board of the network device communicates with other network devices within the cluster system via the local interconnection board based on the communication agent board number, wherein the local interconnection board is a line card on which interfaces for interconnecting the network device to network devices in the cluster system are located; after a cluster interface registration of the local non-interconnection board and local interconnection board on the cluster main control board, each of the local non-interconnection board and the local interconnection board receiving and storing a mapping relationship between local interface information of the network device and global interface information of the network device sent by the cluster main control board, wherein the local interface information of the network device comprises local interface information of all local line cards of the network device, the local interface information comprises serial number and local board number of each line card of the network device, the serial number comprising frame number of the network device and local board number of corresponding line card, the global interface information of the network device comprises a global board number of each line card of the network device, wherein the mapping relationship between local interface information of the network device and global interface information of the network device sent by the cluster main control board comprises the serial number, the local board number, and the global board number of each line card of the network device.