Reassembly is an important operation for receiving network data. A fragment with errors is discarded by the conventional reassembly, which renders the information content of the whole fragment lost. The paper claims that the underlying associated relationships among the network data may bring the gain of Forward Error Correction (FEC). It describes the reassembly model based on multiple long-data and proposes a Forward Error-Tolerant Reassembly method based on the Associated Relationships among the network data (FETRAR). FETRAR is able to work alone without the explicit cooperation of the sender entity or other network entities. Simulation and test results illustrate that FETRAR outperforms the Conventional Reassembly method (CR) dramatically.