[ns] eval $val(traffic) traffic 20 4 0.2 0.1

[Raja Zahilah Raja Mohd. Radzi]

Hi,
Can anybody help me...
What is the meaning of 0.2 and 0.1 in this phrase: eval $val(traffic)
traffic 20 4 0.2 0.1
I know that 20 and 4 is the node source and destination.
Thks!