[ns] How to get the forwarding node id

[Liang Qin <lqin@sce.carleton.ca>]

Hi ns-users,

I'm looking for the instance variable of packet whih I can know the forwarding
node's id. 

In the struct hdr_cmn, there is a prev_hop_  variable, but when I print it out,
for every packet, it's 0.

could anyone give me suggestion?

Thanks!

Liang Qin