proc StartTrafficNgpfHlt {} {
    puts "\nStartTrafficNgpfHlt"
    set startTrafficStatus [::ixiangpf::traffic_control -action run]
    if {[keylget startTrafficStatus status] != $::SUCCESS} {
	puts "\nError StartTrafficHlt: $startTrafficStatus\n"
	return 1
    } 

    # By including VerifyTrafficState, it will wait up to 15 seconds until
    # traffic is started before returning.
    VerifyTrafficState
    return 0
}