Why the Japan Earthquake Didn't Take Down the Country's Internet

The undersea cable network that connects Japan to the world is damaged, but working.

3 min read

Why the Japan Earthquake Didn't Take Down the Country's Internet

The news from Japan is still pretty grim. Four days after a 9.0-magnitude earthquake shook the country, engineers are trying to prevent further explosions at a damaged nuclear power plant, and Japan’s largest electric utility has introduced rolling blackouts. But here's a piece of good news for one of the most wired societies on the planet: For the most part, the Internet is working.

The fiber optic network of undersea cables that connect Japan to the rest of the world was damaged when the earthquake struck beneath the Pacific seafloor, about 200 kilometers from Japan's northeast coast. The Wall Street Journal reports that many telecom operators have battled service disruptions, and anecdotal reports from Japan residents (including IEEE Spectrum commenters) suggest that some people have experienced slow Internet speeds, especially when accessing international sites.

But the situation could have been far worse. TeleGeography, a company that keeps tabs on Internet traffic around the world, told IEEE Spectrum that the undersea cable network experienced "limited" damage due to the earthquake. While more than a dozen undersea cable networks land in Japan, most of the landing stations are in areas that weren't too damaged by the quake. Companies whose cables were impacted have mostly been able to reroute traffic through intact cable lines to avoid major service problems.

From TeleGeography:

Most of Japan's cable landing stations are well to the South of Tokyo, or on the other side of the sheltered inlet that becomes Tokyo Bay.  We're not aware of disruptions to any of the many cables that land here.  All of the cable systems that have reported outages also operate cables that land to the South of Tokyo, so no system appears to have suffered a complete outage....

All of the outages appear to be on cable segments that land in the Ajigaura or Kitaibaraki landing stations, approximately halfway between Tokyo and Sendai.

Some of the damage reports are already in. According to TeleGeography:

* The Hong Kong-based cable-network operator PacNet has reported damage to two segments of its East Asia Crossing undersea cable, which connects Japan to other parts of Asia.

* Japan's NTT Communications Corporation has reported damage to some segments of its PC-1 submarine cable system, which connects Japan and the United States.

* Korea Telecom has also reported that a segment of the Japan-US Cable Network is damaged.

* Chunghwa of Taiwan has reported damage to segments of the Asia Pacific Cable Network 2.

UPDATE: The monitoring company Keynote Systems has more info on how telecoms have coped with the cable problems. Over the weekend, Keynote told us that they'd detected few large-scale problems with internet service. Now the company has provided more details of the types of glitches that have occurred since the earthquake, and the steps telecoms have taken to deal with them. From a Keynote statement:

We captured some peering issues (delays for traffic transiting from one major carrier to another) on Saturday night, 9 pm Pacific. In the graphic below we can see that traffic from Sprint to NTT had 50% packet loss and latency of almost half a second:

The bottom chart shows a 4-hour span today. The lack of troublesome red numbers suggests that telecoms have found short-term fixes to their problems.

Keynote also passed along messages from Japan's NTT Communications Corporation, the country's primary Internet backbone provider. NTT announced today that it will send out submarine cable repair ships within the next 24 to 48 hours to work on busted cables just offshore from the landing station. NTT also warned of the potential for more problems:

It is possible that we may experience an increase in latency and packet loss during periods of peak utilization, specifically 12:00 to 15:00 UTC. Our engineers and operations staff continue to work towards restoring additional capacity on our cable systems and return them to full functionality.

Images: TeleGeography; Keynote Systems

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