Abstract: A checkpointing method in a network device fault tolerant system using virtual machines. In one embodiment, the network device has an input port, an output port, an active virtual machine and a standby virtual machine, a network application on the active virtual machine which manipulates data present on the input port and transmits the manipulated data from the output port; a checkpoint engine on the active virtual machine; and an interface agent, on the active virtual machine, having callable functions to move data from the input port to the output port. The method includes the steps of determining, by the checkpoint engine, that a checkpoint is required; requesting by the checkpoint engine that the interface agent quiescent itself; returning, by the interface agent to the network application, an indicator that no packets are available regardless of whether or not packets are arriving at the input port.

Abstract: A checkpointing method in a network device fault tolerant system using virtual machines. In one embodiment, the network device has an input port, an output port, an active virtual machine and a standby virtual machine, a network application on the active virtual machine which manipulates data present on the input port and transmits the manipulated data from the output port; a checkpoint engine on the active virtual machine; and an interface agent, on the active virtual machine, having callable functions to move data from the input port to the output port. The method includes the steps of determining, by the checkpoint engine, that a checkpoint is required; requesting by the checkpoint engine that the interface agent quiescent itself; returning, by the interface agent to the network application, an indicator that no packets are available regardless of whether or not packets are arriving at the input port.