  Large-scale disaster management applications are among the several realistic
applications of the IoT. Fire detection and earthquake early warning
applications are just two examples. Several IoT devices are used in such
applications e.g., sensors and robots. These sensors and robots are usually
heterogeneous. Moreover, in disaster scenarios, the existing communication
infrastructure may become completely or partially destroyed, leaving mobile
ad-hoc networks the only alternative to provide connectivity. Utilizing these
applications raises new challenges such as the need for dynamic, flexible, and
distributed gateways which can accommodate new applications and new IoT
devices. Network Functions Virtualization (NFV) and Software Defined Networking
(SDN) are emerging paradigms that can help to overcome these challenges. This
paper leverages NFV and SDN to propose an architecture for on-the-fly
distributed gateway provisioning in large-scale disaster management. In the
proposed architecture, the gateway functions are provisioned as Virtual Network
Functions (VNFs) that are chained on-the-fly in the IoT domain using SDN. A
prototype is built and the performance results are presented.
