The work of cutting back to the old equipment was implemented as a countermeasure for the problem that occurred when switching the IoT service server to new equipment.At this time, measures were implemented to promote location registration for the connected IoT device.
Due to the mechanism of the mobile phone network, communication cannot be performed unless the device position is registered.In order to continue communication even after returning to the old equipment, it was necessary to register the location of the IoT device, so it was necessary to register the location.
However, at around 17:00 on March 14, due to the performance of old equipment, a large number of signals could not be processed, the location registration signal was resent, and traffic increased, making it difficult to communicate.At 17:37, a network control was conducted to regulate location registration on networks nationwide.
According to Tamura, the voice service has become difficult to use due to the congestion of the exchange.On the other hand, packet communication services said that if the user moved to update the location information, the location information could not be updated due to the congestion of the signal exchanger, making it difficult to use.
These events appear in the form of "4G" or "5G" displayed on the top right of the smartphone, for example, or "outside the area" displayed on the top right of the smartphone.
At around 19:57 on March 14, the network control was alleviated, but the communication was crowded again.This is the result of the recovered network in addition to the traffic of IoT, and communication such as general smartphones overlap.
Approximately 2 million users were not able to register (= communication).This figure refers to the size of the event that could not be registered in the docomo line and could not communicate with the docomo line.Even if the location is registered, the network is crowded and it may be difficult to communicate, and it does not indicate the entire impact scale.
On the other hand, the company said that it was difficult to calculate the number of users affected accurately, and that there was a 4 % decrease in voice calls and 4 % in data communication compared to the previous week.
As of 20:00 on the 15th, 5G and 4G recovered, but 3G is still difficult to use.As a measure to prevent recurrence in the future, Mr. Tamura raised two points to reconfirm the processing capacity in a different state from normal operation and to review the appropriate switching procedure based on the processing capacity confirmed, and completed it in late October.I wanted to do it.