Conclusion
This paper has evaluated the benefit of content caching in IP over WDM core networks with respect to current and future networks. It compares power savings due to caching when network devices are provisioned for peak traffic and when the network is equipped with sleep-mode capable hardware. It also evaluates the power consumption under lightpath non-bypass and lightpath bypass. Moreover, it investigates the potential of caching as a power efficient solution if the power consumption of transport significantly decreases. Finally, it evaluates the power consumption of the combined effect of all considered network features as well as daily energy consumption reductions due to caching. The results reveal that sleep-mode capable equipment reduces a substantial amount of power due to traffic adaptation. Even though, caching introduces additional power savings of up to 38% of power consumption with and without sleep-mode capabilities. These savings increase to 42% under variable caching when sleepmode capabilities are implemented. The results also show that when the power consumption of transport decreases, similar caching power savings of up to 42% are achieved, however, the optimum cache sizes that result in minimizing power reduce. This influence is also observed when lightpath bypass is implemented, since remote access for video content is more favorable. The power savings due to caching are up to 46% and 42% under lightpath nunbypass and lightpath bypass, respectively. The similar power saving figure of 42% achieved under different scenarios is due to the constant input traffic used in the evaluation where caching reduces the power consumption of download traffic alone. When combining all network features, caching reduces up to 22% and 43% of power consumption under current and future optical networks, respectively
