The gateway has the role of interfacing the
constrained link layer technology used in the sensors cloud with
traditionalWANtechnologies used to provide connectivity to the
central backend servers. The gateway hence plays the role of
6LoWPAN border router and RPL root node. Furthermore, since
sensor nodes do not support CoAP services, the gateway also
operates as the sink node for the sensor cloud, collecting all the
data that need to be exported to the backend services. The
connection to the backend services is provided by common
unconstrained communication technologies, optical fiber in this
specific example.