[ns] routing algorithm

[Sencun Zhu]

Hi, dear all, it is a little strange to find in ns the routing algorithm
is based on cost,which by default the costs for all the links is the same 
(1) ,since I can not figure out the relation between cost and delay,
actually I find in ns the delay can not affect the route, so does this
mean every time for a link, besides setting the bindwidth and delay, also
we need to set the cost? or please tell me where I have missed.

thanks.

sencun