  In this work we discuss proxy architectures which interconnect IoT domains
running CoAP with the rest of Internet including micro datacenters and other
domains building scalable hierarchical architectures. We assume that CoAP
domain is terminated by an IoT proxy with cache, and we investigate several
design issues with respect to successful data transmission, round trip delay
and energy consumption. We present performance data for the case when proxy
autonomously maintains data freshness which clearly point to efficient design
choices.
