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Still No Japanese Exaflood in Sight

We’ve looked at Japanese bandwidth use in the past and concluded that widespread FTTH deployment is not creating a dramatic jump in bandwidth growth. A recent paper out of Japan with updated data reinforces this conclusion.

Japan is by far the worlds largest FTTH deployment and is the best proxy for predicting future of traffic growth as a result of faster broadband speeds. It also doesn’t hurt that Japanese statistics are both plentiful and as unbiased as one can find. The Japanese Ministry of Internal Affairs and Communications (MIC) is tasked with tracking statistics for all things telecom in Japan. It great data and it is all free.

The MICS data illustrates Japanese FTTH growth and a DSL subscriber downtrend for the past 2 years.


The important takeaway here is that all broadband growth in Japan for the last two years has been high speed FTTH subscribers. One would think that growth in the availability of fiber based broadband would drive traffic growth, but the data doesn’t show this.

In September 2007 we observed that while subscriber growth was on a tear in Japan, traffic growth was not growing at the rates commonly referred to in the media (see “The Bandwidth Explosion Myth”). We arrived at this conclusion by combining traffic growth data and subscriber growth data from the MIC. Our conclusion was per-user bandwidth growth in Japan was only 18% per annum. We presented this conclusion at OFC in 2008.

The MIC released a new study that examines traffic growth in Japan with detailed statistics on per-user traffic growth. They reached the same conclusion we reached over a year ago. The below chart illustrates traffic growth as aggregated from various peering points in Japan, and for the first time includes estimates (right scale) of per-user upload and download usage.


The MIC results show per user growth in line with our estimates though they use different Y-axis units. From 2004 through 2007 we estimated per-user download bandwidth grew at 18% per year. The MIC data, which includes 2008, shows download usage roughly doubled between 2004 and 2008, a growth rate of 18-19%.

More importantly, the additional data through 2008 shows that no significant trend change in bandwidth usage is underway. Given Japan has the largest installed base of FTTH in the world we feel it is premature to conclude that the deployment of high-speed broadband upgrades result in any significant change in bandwidth usage.


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  1. Is it possible the Japanese are transitioning to consuming more bits through their phones and data cards?

    Posted by YF | March 17, 2009, 9:49 AM
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