FlexPath: A Customizable and QoS-aware Multipath Transmission Protocol for Heterogeneous Networks

With the increasing diversity of network applications, the quality of service (QoS) requirements vary significantly across different domains. As network resources become increasingly abundant, single-path transport protocols fail to fully utilize the multiple network interfaces available on modern end devices. Traditional multipath transport mechanisms are rigid and lack the flexibility for customization or real-time adaptation based on dynamic path conditions, highlighting the need for a customizable and adaptable multipath transport solution. To address this challenge, we propose FlexPath, a customizable multipath transport protocol designed for heterogeneous networks and complex QoS demands. FlexPath decouples multipath transport control functionalities in user space, enabling parallel use of heterogeneous transport protocols and differentiated transmission algorithms. It supports dynamic optimization based on realtime network conditions and application-level QoS requirements. Experimental results demonstrate that FlexPath significantly reduces transmission latency by $\mathbf{4 4 \% - 6 8 \%}$ compared to UDT and $\mathbf{9 \% - 4 0 \%}$ compared to MPTCP and MPQUIC, while maintaining comparable path aggregation overhead to existing multipath transport solutions.