proc ModifyStreamLineRateHlt { streamId ratePercentage } {
    # streamId format could be any of the followings:
    #      ::ixNet::OBJ-/traffic/trafficItem:1
    #      ::ixNet::OBJ-/traffic/trafficItem:1/configElement:1

    puts "\nModifyStreamLineRateHlt: $streamId : $ratePercentage\%"
    set trafficItemStatus [eval ::ixia::traffic_config \
			       -mode modify \
			       -stream_id $streamId \
			       -rate_percent $ratePercentage \
			      ]
    if {[keylget trafficItemStatus status] != $::SUCCESS} {
	puts "\nError ModifyStreamLineRateHlt: $trafficItemStatus\n"
	return 1
    }
    return 0
}