In East-Japan Catastrophic Disaster in March 2011, the earthquake and tsunami dramatically affected communication infrastructures. Although cellular networks were available in some areas, network operators restricted call requests due to heavy network congestions. We experienced and learned that it is impossible to respond to dramatically increased communication demand only by using cellular networks, which implies the need of integrating any available networks to provide a huge number of people in disaster areas with network access services. To this end, we focus on an integrated heterogeneous network constructed by connecting regional networks deployed in stations, offices, etc. In such network, protocol optimization is a significant issue to achieve highly efficient utilization of network resources because the available resources are limited due to the damages of disasters and unstable power supply. In this research, we aim to optimize network protocols used in regional networks in terms of improving communication efficiency in the integrated heterogeneous network allowing network access in disaster areas.