5. Operative supervision of the network architecture

In this report the procedures for the operative supervision of the network architecture have been illustrated. The system requirements of a high-survival radio network, operating in the HF band to provide a minimum flux of information for management and control of the ECIs and CGAs are here examined. It is considered the case of a terrorist attack that may put out of order the Internet connection between considered critical infrastructures. The procedure for the operative supervision of the HF back-up network involves a series of passages including, as first step, the “warm” stand-by condition of HF back-up network and, secondly, the hierarchic of Distributed Supervision Function (DSVF) program enabling, in the proper order, all the operations necessary to put on the network and to return to the “wait” state. Following the procedure DSVF the terminal points equipped by PCs where the program resides evaluate the physical and logical information of the network position of the CGA or ECI, including a priority list of the infrastructures to be alerted. The relevant point concerns the possible employment of the same frequency in each terminal of the HF network. It is worthy to note that when the supervision system triggers the back-up network all the TX/RX points located in the ECIs or CGAs must communicate with the same initial frequency and eventually exploit other frequencies given by the planned procedures, according to degradation of the propagation in the disturbed channels. Of course, in such a condition the transmission of data-packets already described in [6] are considered essential. Eventually a redundant process when the propagation is not optimal [7] could be necessary. Since the whole network (or part of it) is always tuned at the same frequency, it has to change in time according to the propagation condition even in the stand-by state. When the network has to be enabled to avoid collisions in the data packets independently on the mode and type of data, the contention based technique seems promising in short link turnaround time. On the contrary for long turnaround time a contention free approach can be employed. In the DSVF operation, one of the important point concerns the criteria of warning alert and the procedures to activate and to deactivate the back-up network. In the previous report [1] these criteria have been extensively analyzed. Description of some Internet failure scenarios are considered among a large variety of possible situations. In fact this report deals with two main Internet failure scenarios: a most reasonable scenario and worst case analysis. The other cases fall between these two extremes. In the first case the HF link between the CGA and the ECI overcomes the problem locally and the whole network utilizes the broad band communication. A different case is when the attack involves more ECIs and CGAs. Here the HF network will be activate and the Internet connection will be completely ignored but not disconnected. In both cases a system for the supervision of the Internet links checks systematically if the informatics attack is finished. The constant control of the Internet is necessary in order to establish if and when to activate the HF back-up network. At the end it has been described the condition in which the Internet becomes available again, the HF back-up network nodes/links must be deactivated and the Internet links reactivated.