A network node includes one or more network adapters and a bonding driver. The one or more network adapters are configured to communicate respective data flows over a communication network by applying a transport layer protocol that saves communication state information in a state of a respective network adapter. The bonding driver is configured to exchange traffic including the data flows of an application program that is executed in the network node, to communicate the data flows of the traffic via one or more physical links of the one or more network adapters, and, in response to a physical-transport failure, to switch a given data flow to a different physical link or a different network path, transparently to the application program.