Cisco’s Visual Network Index forecasts that Internet traffic in New Zealand will grow at a compound annual growth rate of 44% between 2010 and 2015. They expect the average end user to be downloading almost 14GB per month in 2015, and as a result, they predict average national IP traffic rates of 237 gigabits per second.

Based on the Cisco VNI, population data from Statistics NZ, and fibre maps from Telecom New Zealand, I’ve modeled what I expect to be the basic topology and aggregate peak backhaul demand for the South Island in 2015. Numbers next to each city indicate expected peak demand (calculated at 150% of average demand) in gigabits per second. Each link in the Southern ring will require capacity to transit all traffic in the ring in case of a single link failure. Each link in the Northern ring will require capacity to transit all traffic in both rings. Exit points to North Island cities Levin and Wellington are indicated by arrows in the diagram from Nelson and Blenheim.

With much of New Zealand’s Internet traffic originating either in Auckland or offshore, demand for North-South national transit is set to increase dramatically. New Zealand’s three national transit providers may be running 10 gigabit networks today, but they’ll need to make the leap to 100 gigabit backbones quickly to keep pace with peak demand.