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Generate a series packet sizes for network testing
Lists example from a Well House Consultants training course
More on Lists [link]
Source code: pk4.tcl Module: T206
# Setting traffic in small medium and large packets # where we know the proportion of BYTES in packets of each size ############################# proc maketraffic {perc size rez} { # First parameter - percentage of traffic in packets of each size (a list) # Second parameter - size of each of the packet types (a list) # Third parameter - the NAME of a variable to use for a returned list # We want to output a list of packet sized from this proc, which we # do via the regular "return". However, we may also want to pass # back a table of percentages for each packet size which we'll do # via the third parameter upvar $rez tealeaves set ecount [llength $perc] set totrat 0 # Work out the number of packets of each size for a megabit of data for {set i 0} {$i < $ecount} {incr i} { set nprop [expr 1000000 * [lindex $perc $i] / 100. / [lindex $size $i]] lappend prop $nprop set totrat [expr $totrat + $nprop] } # Work out the PROPORTION of each size of packet to get the required # proportion of traffic set ratiosofar 0 for {set i 0} {$i < $ecount} {incr i} { set nprop [expr [lindex $prop $i] / $totrat] set ratiosofar [expr $nprop + $ratiosofar] lappend ratios $ratiosofar lappend c 0 } # Use the randomiser to choose which packet to send for {set counter 0} {$counter < 10000} {incr counter} { set trigger [expr rand()] for {set i 0} {$i < $ecount} {incr i} { if {$trigger < [lindex $ratios $i]} { set c [lreplace $c $i $i [expr 1 + [lindex $c $i]]] lappend stream [lindex $size $i] break } } } # Go work out how much traffic in each size of packet set tottra 0 for {set i 0} {$i < $ecount} {incr i} { set thistraffic [expr [lindex $c $i] * [lindex $size $i]] lappend traffic $thistraffic set tottra [expr $tottra + $thistraffic] } # And reduce that to a percentage for {set i 0} {$i < $ecount} {incr i} { lappend tperc [expr 100 * [lindex $traffic $i] / $tottra ] } # Use the upvar variable to return the statistics set tealeaves $tperc # And return the relating list of packet sizes return $stream } ############################# # Seed the random number generator (default is actually # clock seconds - we have added here explicitly to show # how to do it) puts [clock seconds] expr srand([clock seconds]) # Set up some sample patterns set cellular_pc "80 5 15" set cellular_sz "64 576 1518" set data_pc "30 10 60" set data_sz $cellular_sz set sophie_pc "60 10 7 2 6 15" set sophie_sz "64 99 150 237 576 1518" # Generate and test those patterns set generate [maketraffic $cellular_pc $cellular_sz tlevs] # puts $generate puts $tlevs set generate [maketraffic $cellular_pc $cellular_sz tlevs] # puts $generate puts $tlevs set generate [maketraffic $data_pc $data_sz tlevs] # puts $generate set generate [maketraffic $sophie_pc $sophie_sz twiddle] puts $tlevs puts $twiddle Learn about this subject
This module and example are covered on the following public courses:
* Learning to program in Tcl * Tcl Programming * Tcl Programming Also available on on site courses for larger groups Books covering this topic
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other closely related examples on the "Lists" module index page.
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