.SS "OpenFlow Options"
.TP
\fB\-\-datapath\-id=\fIdpid\fR
-Sets \fIdpid\fR, which must consist of exactly 16 hexadecimal digits,
+Sets \fIdpid\fR, which must consist of exactly 16 hexadecimal digits
+and may not be all-zero,
as the datapath ID that the switch will use to identify itself to
OpenFlow controllers.
.IP