## 8 Conclusions  
In this work, we have compared a recently proposed protocol, the multi-parent hierarchical (MPH) protocol, with two well-known protocols, the _ad hoc_ on-demand distance vector (AODV) and the dynamic source routing protocol (DSR). In the simulation results, we observed that the MPH outperforms the other ones, for all metrics that we tested: the number of packet retransmissions, the CSMA inner loop retries, the number of nodes answering the queries from the coordinator (sink) node and the energy consumption.  
The assessed metrics describe the network performance against various types of jamming. The large deviations of the metric variables for AODV and DSR when attacking conditions occur may make a later construction of a jamming detector easier. In contrast, for MPH, the changes in the metrics values are not as large as the deviations shown in AODV and DSR; this could be a desirable behavior from a performance perspective, but making the construction of a new detector more difficult; thus, further metrics could be proposed and analyzed according to specific protocols.  
2D representation of the metrics distribution clearly shows that the MPH protocol can better manage the jamming impact on the network. We observed that under a jamming attack, MPH intrinsically isolates the area under attack and re-routes the traffic using the rest of the network; this is true, even if the attacker keeps moving. Therefore, WSNs with the MPH routing protocol present less performance deterioration when facing jamming activity. In MPH, the periodic updating of neighbor tables produces a positive effect to deal with the links affected by a jammer node. In addition, the combination of proactive and reactive mechanisms of MPH allow the reconfiguration of the network topology without generating excessive overhead.  
Regarding AODV and DSR, which are reactive protocols, if the topology is constantly changing, the overhead increases due to the route discovery mechanism; this can generate more packet loss, and the attack becomes more aggressive and extensive, as can be seen in Figures 7-9.  
From the simulation results, we can conclude that the resilience provided by routing protocols for self-configuring WSNs can help to deal with jamming activity. The network topology should adapt dynamically according to the available resources and the internal mechanisms of the underlying routing protocol. The resultant performance depends not only on the time to react against the attack, but also on the efficiency to achieve a new topology.  
As future work, we suggest improving the reaction under a jamming attack. Since, at present, the MPH protocol uses a persistence counter to score neighbor steadiness, the use of a larger history of the neighbor activity may reduce the number of false positives in the decision to remove a node from the neighbor tables; however, this would produce an increased delay in the reconfiguration of the topology. Therefore, by helping this mechanism with the strength of the signal and other MAC and network layer parameters, a multi-feature detector or a routing protocol with better capabilities to deal with the jamming attacks could be constructed.  
This work has been partially supported by the Consejo Nacional de Ciencia y Tecnologia (CONACyT, Mexico) and Tecnologico de Monterrey.