Multipath routing problem

try using
Node set multiPath_ 1

instead of
node_ set multiPath_ 1

Use that line just after creating the simulator instance and just before creating any node.
Probably it will work as you expected.

I used in one of my previous work, and it worked correctly.

a similar discussion con be found in the following link.

http://mailman.isi.edu/pipermail/ns-users/1999-November/006175.html