Modern onboard equipment complexes (OEC) utilize AFDX and FC-AE-ASM-RT switched networks implementing a virtual link-based approach to real-time data transfer. The main drawback of these networks is their limited or absent support for dynamic reconfiguration of virtual links, which makes impossible the dynamical recomposition of OEC operation modes, particularly in case of multiple equipment failures. To remove these drawbacks, in this paper an approach is proposed to use software-defined networks (SDN) as onboard real-time networks. The proposed approach is based on implementation of a virtual link-based technology (similar to those used in AFDX and FC-AE-ASMRT) in an SDN supporting OpenFlow 1.3 protocol. The approach was implemented as a functional prototype and experimentally evaluated in a virtual network environment based on Ofsoftswitch13 software SDN switches and RUNOS controller. The experiments indicated that the proposed data exchange scheme allows the transfer of messages within the given limits on delay and jitter, and does not allow violation of constraints on a virtual link bandwidth. The experiments also confirmed that dynamic reconfiguration of virtual links in SDN does not interrupt the data transfer through unchanged virtual links. An important direction for future work is development of algorithms for dynamic creation of virtual link routes in course of OEC reconfiguration. The final goal of the work is to create an SDN-based network technology supporting both real-time data transfer and automatic network reconfiguration in case of OEC mode change, including parrying multiple failures.