Apologies for NTT docomo's difficulty to use in Tokyo on January 25, due to sudden increase in smartphone users

NTT DoCoMo apologizes for the case where a situation where FOMA voice / packet communication service is difficult to use in some areas of Tokyo between 8:26 AM and 1: 0 8 on January 25, 2012 I will give out and explain the cause.

Notice from docomo: 【apologies】 About situation where it is difficult to use FOMA voice / packet communication service on January 25, 2012 | News | NTT DoCoMo
http://www.nttdocomo.co.jp/info/notice/page/120126.html

Notice of communication trouble: 【apologies】 About FOMA's voice and packet communication service on January 25, 2012 Notice | Notice | NTT DoCoMo
http://www.nttdocomo.co.jp/info/network/kanto/pages/120126_2_d.html

Press Release Material: 【Apology】 About FOMA's Voice and Packet Communication Service on January 25, 2012 Notice | Notice | NTT DoCoMo
http://www.nttdocomo.co.jp/info/news_release/2012/01/26_00.html

The equipment which caused the event is a packet switch, the affected area and the number of influential people are as follows.

· Affected areas: Tokyo area (Katsushika Ward, Edogawa Ward, Koto Ward, Minato Ward, Shinjuku Ward, Chiyoda Ward, Chuo Ward, Shinagawa Ward, Bunkyo Ward, Sumida Ward, Ota Ward, Meguro Ward, Shibuya Ward, Setagaya Ward) Some areas
· Number of people affected: up to 2.25 million

The occurrence is as follows.

· To respond to the increase in smartphone subscribers, switch to a new packet switch from early Wednesday, January 25
· As the traffic rises around 8:26 am, the operation of the new packet switch becomes unstable
· Since traffic increased further from around 9:00 am, a congestion state occurred in the network, and the packet service and the voice service are difficult to be connected due to automatic network regulation
· From around 10:56 am, in order to improve the congestion state in the network, work of returning the packet switchboard to the state before switching is performed, and the restriction is released sequentially from the base station under the switch which completed this work
· Restriction of all base stations was canceled at 1:08 pm and recovery completed

When arranged in chronological order


It was in the figure that event occurred


It seems that switching overview was like this


The cause has been announced as follows.

- Smartphone applications (VoIP, chat, etc.) that frequently require "control signals" suddenly popularized, and control signals on the network are increasing, and in such a situation, new type packet switch , We found that the control signal overflowed the processing capacity of the packet switch

In the figure, such a feeling, detailed numerical values ​​are also shown


There is an interesting description that AndroidOS communicates every 28 minutes as a factor of increasing the control signal, and furthermore each application sends control signals every 3 to 5 minutes


The future measures seem to be as follows.

· Perform a comprehensive inspection of packet switchboards nationwide by the middle of February and implement measures such as expanding facilities as necessary as necessary
Monitor the amount of control signals that is rapidly increasing with the increase in smartphones, and reflect more appropriate signal amount prediction in equipment

Looking at the following countermeasure table, we will further increase the processing capacity in the middle of August and will also cooperate with carriers all over the world, so it seems that we have reached a level that we have to do quite large measures is


NTT DoCoMo thought that the amount of traffic that smartphones exploded was okay, but that this docomo is on the verge of this danger also worries about what other carriers are like It is place.