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What Does Japan’s Major communications Failure Reflect?

(Cui Liangliang) Since SoftBank suffered a major communications failure in December 2018, Japan has suffered another major cyber accident.


On October 14, 2021 local time, operator NTT DoCoMo’s mobile network experienced a major communication failure across Japan, leaving a large number of mobile phone users unable to make calls and data communications.


According to relevant sources, NTT DoCoMo found a problem with the new equipment when it replaced the updated location information server (HLR/HSS) from midnight on October 14. According to the uncertain information, the new device is an overseas brand, and the frequency between the end IoT devices does not correspond to the problem. It then switched back to the old devices and ordered the IoT terminal devices to log back to the old devices in batches of 200,000 units, generating a huge amount of traffic, which eventually caused the entire NTT DoCoMo system to fail and the national communications to break down. First voice failure, then data communication failure.


The accident was widespread and shocked Japan.


About 2 million people in Japan are reported to be affected, most of them with 3G or no signal. The Ministry of Internal Affairs and Communications demanded a reasonable explanation from NTT DoCoMo and measures to prevent such a situation from happening again. Japan’s Internal Affairs and Communications minister said at a press conference after a cabinet meeting that it was regrettable that the mobile network, which is an important infrastructure for People’s Daily life, had suffered a massive failure. The Ministry of Internal Affairs and Communications takes this matter very seriously and has asked NTT DoCoMo to investigate and report the cause of the accident and the extent of its impact in a timely manner so as to give a full explanation to the vast number of users. It is hoped that NTT DoCoMo will fulfill its social responsibility and take all possible measures to prevent similar accidents from happening again.


NTT DoCoMo’s management publicly apologized for the inconvenience caused to customers and many others and said it would work hard to prevent a recurrence.


During the incident, NTT DoCoMo conducted emergency network operations at 8 p.m. on August 14 to restore communication in some parts of the network, but the network was blocked again due to network congestion. In the end, 4G and 5G communications will resume at 5 a.m. on Friday, while 3G communications will resume at midnight on Friday.


NTT DoCoMo said the incoming signaling traffic was much higher than expected.


It appears that this is a major network failure caused by network cutover failure.




The accident has prompted soul-searching in Japan. After the glitch, many Internet users said online classes were suspended, taxis were unable to use smartphones to pay, and electronic tickets to watch movies were unable to be displayed on site…… It has brought great inconvenience to our daily life.


Industry experts in Japan say the debate over the incident has been disappointing: more people believe that people should not trust the system too much and should always be personally prepared for a system crash, rather than asking why traffic generated by just 200,000 IoT terminals could eventually bring down Japan’s flagship carrier. The problem needs to be addressed head-on. Japan is too backward in all kinds of information technology and does not actively learn. System crashes are frequent, and even COVID-19 infections are transmitted by fax machines.