说明：  #Create a simulator object set ns [new Simulator] #Define different colors for data flows (for NAM) $ns color 1 Blue $ns color 2 Red #Open the NAM trace file set nf [open out.nam w] $ns namtrace-all $nf #Define a finish procedure proc finish {} { global ns nf $ns flush-trace #Close the NAM trace file close $nf #Execute NAM on the trace file exec nam out.nam & exit 0 }