[ns] could pl check, am I generating VBR traffic?

Hi guys

I want to use the following code for generating VBR traffic.

# Create a VBR traffic source and attach it to node3
set vbr1 [new Application/Traffic/Exponential]
$vbr1 set packetSize_ 280
$vbr1 set rate_ 600k
$vbr1 set burst_time_ 150ms
$vbr1 set idle_time_ 100ms
$vbr1 attach-agent $udp1

http://ns2homeworkforbeginner.blogspot.ca/2008/10/ns2-wired-simulation-with-tcp-cbr-vbr.html

DO YOU THINK THIS IS A RIGHT WAY OF GENERATING VBR TRAFFIC?

PLEASE reply.

regards
Bikahs