mobile traffic, closer to the end users, thus reducing latency and traffic load across the network infrastructure. Network Function Virtualization (NFV) is widely regarded to as an enabling technology for MEC (see, e.g., [@etsi-wp]). Recent works have studied the radio techniques needed to enable MEC [@mec-radio], its relationship to the Internet-of-things [@mec-iot] and context-aware, next-generation networks [@mec-5g]. Closer to our scenario, the authors of [@moving] study how caches and servers should be placed in the network as its load changes over time. Regarding MEC and caching, a prominent application is mobile video streaming. As an example, [@multiop-caching; @cdn1] account for layered video coding techniques, and address the problem of placing the right layers at the right cache – with [@multiop-caching] also accounting for cooperation between operators. Other works [@proactive-caching; @wons] aim at [*foreseeing*]{} the content demand, in order to proactively populate caches or serve users.

5G will significantly exploit the MEC paradigm, and a substantial body of research is devoted to the problem of placing VNFs across the network providers’ servers. As an example,[@AHirwe16; @TKuo16; @ABaumgartner15; @FJemaa16; @BAddis15] tackle the problems of VNF placement and routing from a network-centric viewpoint, i.e., they aim at minimizing the load of network resources. 