1. A system for checkpointing data in a parallel computing system having a plurality of computing nodes, each node having one or more processors and network interface devices for communicating over a network, said checkpointing system comprising: one or more network elements interconnecting said network interface devices of computing nodes via links to form a network; a control device to communicate control signals to each said computing node of said network for stopping receiving and sending message packets at a node, and to communicate further control signals to each said one or more network elements for stopping flow of message packets within said formed network; and, a control unit, at each computing node and at one or more said network elements, responsive to a first control signal to stop each of said network interface devices involved with processing of packets in said formed network, and, to stop a flow of packets communicated on links between nodes of said network; and, said control unit, at each node and said one or more network elements, responsive to second control signal to obtain, from each said plurality of network interface devices, data included in said packets currently being processed, and to obtain from said one or more network elements, current network state information, and, a memory storage device adapted to temporarily store said obtained packet data and said obtained network state information.