The Advanced Metering Infrastructure (AMI) is a key component of the Smart Grid architecture. The Neighborhood Area Network (NAN) is the portion of the AMI that enables two-way communication between electric, gas and water meters and City Utilities. Many companies are currently deploying wireless NAN architectures based on the IEEE 802.15.4g technology while the Routing Protocol for Low-Power and Lossy Networks (RPL) has been considered as the mesh routing protocol. In this paper, we investigate the dynamics of RPL for routing path maintenance in the presence of jamming attacks. A precise interference model is implemented and tested under a fully compliant RPL draft implementation. The quality of the survivors routing paths in terms of ETX metric is investigated for different density of gateways. The results provide insights for an efficient NAN design in order to minimize the impacts of jamming attacks in the RPL performance.