[ns] Is 802.15.4 the default protocol for mobilenodes in ns2?

[Daniele Manini]

Hello,
i'm going to work with 2.31 version for simulating wireless scenario. I
would like to know:

- is 802.15.4 the default mac protocoll or should i configure some
parameter to set it?
- the cbr traffic generator has the parameter random_ that allows to add
noise to the generating time interval, is this function enabled by
setting it to 1?

Thank you
Daniele Manini