Specifications

CHAPTER 5. TRAFFIC GENERATION 22
Distribution Description
rand normal( mean, stddev ) The Normal Gaussian distribution
with given mean and variance
rand negexp( mean ) Negative Exponential distribution –
usually used for inter-packet time
rand uniform( list ) The values from the given list have
equal probability of appearance
round robin( list ) The values from the list are chosen
one after the other
burst( burst length, inter
burst time, inter-packet time
within burst)
The values are from a burst-type
sequence. Used for inter packet
time to model packets that come in
bursts.
rand histogram( list of pairs:
value, probability)
Each value has the given probability
of appearance
RandomVar( ”expression de-
pending on x”, min value,
max value)
Generates a random numb e r in the
interval [min value, max value] that
has the probability density given by
the expression from the first argu-
ment. The expression can be a func-
tion containing any built-in or user-
defined function.
The input files for the traffic generator follow the XML syntax. You can see below a sample
traffic pattern description.
<TrafficGeneratorConfiguration>
<FunctionDefinition name = "linear" parameters = "slope" >
slope * x
</FunctionDefinition>
<FunctionDefinition name = "poly" >
26+(x/100-3)^5 -3*(x/100-3)^4 -11*(x/100-3)^3+27*(x/100-3)^2+10*(x/100-3)
</FunctionDefinition>
<Pattern name = "sample1" number_of_descriptors = "4096" pa cket _typ e="1 " >
<Source>
1:5, 10, 20:23
</Source>
<Destination>
round_robin(5, 10, 15 : 25)
</Destination>
<PacketSize>
RandomVar("gauss(x,900,10) + 2*gauss(x,1200,10)",800,1400)
</PacketSize>
<InterpacketTime>
rand_negexp(10)
</InterpacketTime>
<VLAN_Data>
<VLAN_Id>
RandomVar("linear(3,x)", 0, 20)
</VLAN_Id>
<VLAN_Priority>
RandomVar("poly(x)", 0, 600)
</VLAN_Priority>
</VLAN_Data>
</Pattern>
</TrafficGeneratorConfiguration>