In the old days, information processing facilities installed in companies were called telephone exchange rooms and computer rooms. They are now called data centers and their amount of information handled and the communication speed have increased dramatically. Also, the conventional method of exchanging information between the head office and branch offices and some external customers, etc., has changed significantly to constant, bidirectional communication between all concerned parties. In particular, as one of the recent major features, the trend toward utilizing a large-scale data center fully prepared for natural disasters and ensuring a high level of security operated by an external company, without having a large-scale data center in-house, is in full swing. Advances in cloud computing, etc. are accelerating this trend.