I am trying to use $node rtObject? to return the handle of an routing node. My code is like this: ... $ns rtproto DV [list $d1 $r1 $r2 $n2 $n1 $n3] set handle [$r1 rtObject?] puts "$handle" ... The value of handle is "", which is empty despite I have initialized all nodes with rtproto before. Does anyone has any clue why this is happen? Any help would be much appreciated. Ian Liu