Rank decrease in rpl-lite

[brianma94]

Hello,

I am working in an MSc project regarding RPL attacks. I am trying to implement the rank decrease attack. To do so, I reduce in one unit the rank of the malicious node modifying the file rpl-dag.c in the function rpl_dag_update_state(void). The original code is:
[...]
curr_instance.dag.rank = rpl_neighbor_rank_via_nbr(curr_instance.dag.preferred_parent);
[...]

My modification is:
[...]
if (select) {
curr_instance.dag.rank = rpl_neighbor_rank_via_nbr(curr_instance.dag.preferred_parent) - 1;
}
else curr_instance.dag.rank = rpl_neighbor_rank_via_nbr(curr_instance.dag.preferred_parent);
[...]
The "select" boolean is used to identify the malicious node.

Checking the output I can realize that the rank is decreased correctly, but the children nodes are not changing their parent to the malicious node although it has a lower rank.

Is this the way to perform this attack or I should modify something else? Is there a way to force the children to select this parent or to decide the best parent after this modification?

Thank you in advance,
Brian

[debug-ito]

By default, rpl-lite uses an Objective Function called MRHOF (rpl-mrhof.c), which has hysteresis behavior. Maybe the rank decrease was not big enough for other nodes to switch parents.