A relay node based on a tunneling protocol, comprising: a communication device, configured to communicate with a receiving node and a transmitting node; a storage device, being configured to store a plurality of instructions; and a processor, coupled to the communication device and the storage device for loading and executing the plurality of instructions stored in the storage device to: control the communication device to receive a packet transmitted by the transmitting node; generate a protocol header related to the packet based on the packet, and calculate a checksum as a checksum block of a user datagram protocol section in a plurality of sections using the plurality of sections in the protocol header at least, wherein the plurality of sections comprises a general packet radio service tunneling protocol section, an encapsulated pseudo Internet protocol version 4 block selected from the plurality of sections in the protocol header and the user datagram protocol section; generate an encapsulated packet, wherein the encapsulated packet comprises the protocol header and the packet; and transmit the encapsulated packet to the receiving node through the communication device for the receiving node to verify the checksum block. a communication device, configured to communicate with a receiving node and a transmitting node; a storage device, being configured to store a plurality of instructions; and a processor, coupled to the communication device and the storage device for loading and executing the plurality of instructions stored in the storage device to: control the communication device to receive a packet transmitted by the transmitting node; generate a protocol header related to the packet based on the packet, and calculate a checksum as a checksum block of a user datagram protocol section in a plurality of sections using the plurality of sections in the protocol header at least, wherein the plurality of sections comprises a general packet radio service tunneling protocol section, an encapsulated pseudo Internet protocol version 4 block selected from the plurality of sections in the protocol header and the user datagram protocol section; generate an encapsulated packet, wherein the encapsulated packet comprises the protocol header and the packet; and transmit the encapsulated packet to the receiving node through the communication device for the receiving node to verify the checksum block. control the communication device to receive a packet transmitted by the transmitting node; generate a protocol header related to the packet based on the packet, and calculate a checksum as a checksum block of a user datagram protocol section in a plurality of sections using the plurality of sections in the protocol header at least, wherein the plurality of sections comprises a general packet radio service tunneling protocol section, an encapsulated pseudo Internet protocol version 4 block selected from the plurality of sections in the protocol header and the user datagram protocol section; generate an encapsulated packet, wherein the encapsulated packet comprises the protocol header and the packet; and transmit the encapsulated packet to the receiving node through the communication device for the receiving node to verify the checksum block.