Trading IP routing stability for energy efficiency: A case for traffic offloading with optical bypass

The ICT and network services economy has exhibited large growth rates with global IP traffic expected to reach 64 exabytes per month in 2014. In addition to operational challenges in managing this traffic load, it is widely recognized that new energy saving approaches will be critical to the ICT sector for sustaining growth. In this paper, we use the optical bypass technique - which is a novel network engineering mechanism in IP-over-WDM networks - in order to exploit the dynamics in the daily IP traffic pattern. We save energy by offloading traffic to optical circuits while, at the same time, considering important aspects of maintaining IP routing stability. We compare the performance of our approach with an already established approach of energy saving, where underutilized IP resources are simply switched off. Our results show that the optical bypass mechanism indeed only slightly outperforms the link switch-off approach in terms of energy conservation, but greatly in terms of IP routing stability. In addition, the proposed approach is more reliable due to higher redundancy in off-peak hours.