public Object down(Event evt) {
        switch(evt.getType()) {
            case Event.VIEW_CHANGE:
                handleViewChange(evt.getArg());
                break;
        }
        return down_prot.down(evt);  // Pass on to the layer below us
    }
public Object down ( Event evt ) { switch ( evt . getType ( ) ) { case Event . VIEW_CHANGE : handleViewChange ( evt . getArg ( ) ) ; break ; } return down_prot . down ( evt ) ; }
Fragment a packet if larger than frag_size (add a header). Otherwise just pass down. Only
add a header if framentation is needed !