  Network function virtualization (NFV) and content caching are two promising
technologies that hold great potential for network operators and designers.
This paper optimizes the deployment of NFV and content caching in 5G networks
and focuses on the associated power consumption savings. In addition, it
introduces an approach to combine content caching with NFV in one integrated
architecture for energy aware 5G networks. A mixed integer linear programming
(MILP) model has been developed to minimize the total power consumption by
jointly optimizing the cache size, virtual machine (VM) workload, and the
locations of both cache nodes and VMs. The results were investigated under the
impact of core network virtual machines (CNVMs) inter-traffic. The result show
that the optical line terminal (OLT) access network nodes are the optimum
location for content caching and for hosting VMs during busy times of the day
whilst IP over WDM core network nodes are the optimum locations for caching and
VM placement during off-peak time. Furthermore, the results reveal that a
virtualization-only approach is better than a caching-only approach for video
streaming services where the virtualization-only approach compared to
caching-only approach, achieves a maximum power saving of 7% (average 5%) when
no CNVMs inter-traffic is considered and 6% (average 4%) with CNVMs
inter-traffic at 10% of the total backhaul traffic. On the other hand, the
integrated approach has a maximum power saving of 15% (average 9%) with and
without CNVMs inter-traffic compared to the virtualization-only approach, and
it achieves a maximum power saving of 21% (average 13%) without CNVMs
inter-traffic and 20% (average 12%) when CNVMs inter-traffic is considered
compared with the caching-only approach. In order to validate the MILP models
and achieve real-time operation in our approaches, a heuristic was developed.
