[Contiki-developers] how can I change the link metric in RPL?

[olfa g. <olf...@gm...>]

Hi all,
I am working on the modification of the objective function based on etx
link metric to support the hop count metric. I want to know first of all
how the etx values of the neighboring nodes are computed?
in rpl.c, the following instruction is written for the rank recalculation:

parent->link_metric = etx;

what is the value of this variable 'etx' and how can I change this value to
the hop count metric? Have you an idea how can I compute the hop count of
the neghbors?

Thanks in advance,

Olfa