Background. The paper proposes a solution to such an urgent problem today, as to ensure the fault tolerance of infocommunication networks with the support of the required level of quality of service. The proposed solution is based on the implementation of an advanced tensor approach to fast reroute with the protection of the level of quality of service under multiple parameters. Objective. The aim of the article is to improve the flow-based fast rerouting model in the infocommunication network, which is based on updated conditions for ensuring quality of service in terms of bandwidth, average end-to-end delay, and probability of packet loss. It was possible to obtain updated conditions for ensuring the quality of service through the use of a tensor approach to modeling infocommunication networks. Methods. As research methods, graph theory, tensor theory, queuing systems were used. For mathematical modeling and experimental studies, the MatLab simulation package was used. Results. As a result of the study, under the conditions of implementing fast rerouting, it was possible to provide the required level of quality of service in the infocommunication network. At the same time, with an increase in QoS requirements, thanks to an improved tensor approach, the updated conditions for ensuring the quality of service while implementing fast rerouting were adequate, which, as a result, contributed to a more efficient use of the available network resource. Conclusions. Implementation of an improved tensor approach to solving the problem of fast rerouting will ensure the fault tolerance of the infocommunication network with the protection of the level of quality of service in terms of bandwidth, average end-to-end delay, and the probability of packet loss.