Networking giant Cisco has said internet traffic will quadruple by 2015, driven by growth in smartphones, tablet computers and appliances connected to the web.

More than 40 per cent of the global population will be online by 2015, contributing to almost a zettabyte of internet traffic that year. A zettabyte is equal to a trillion gigabytes. In its fifth annual Visual Networking Index report, Cisco said traffic was particularly driven by increased consumption of video online from sites like YouTube.