The DEC WANrouter 100/500 supports these tracepoints:

 	HDLC LINK <link_name or *>
 	DDCMP LINK <link_name or *>
 	LAPB LINK <link_name or *>
 	MODEM_CONNECT LINE <line_name or *>
 	NSP PORT <port_name or *>
 	ROUTING CIRCUIT <circuit_name or *>