proc LinkUpDown { portNumber {action down} } {
    # action = down or up

    foreach vport [ixNet getList [ixNet getRoot] vport] {
	# ::ixNet::OBJ-/availableHardware/chassis:"10.205.4.35"/card:1/port:1
	set connectedTo [ixNet getAttribute $vport -connectedTo]
	set connectedTo [lrange [split $connectedTo /] 3 4]
	set card [lindex [split [lindex $connectedTo 0] :] end]
	set port [lindex [split [lindex $connectedTo 1] :] end]
	set port $card/$port

	if {$portNumber == $port} {
	    LogMessage -info "Bringing port $port: $action"
	    ixNet exec linkUpDn $vport $action
	}
    }
}