+.SS "sFlow Monitoring"
+sFlow(R) is a protocol for monitoring switches. A bridge may be
+configured to send sFlow records to sFlow collectors by defining the
+key \fBsflow.\fIbridge\fB.host\fR for each collector in the form
+\fIip\fR[\fB:\fIport\fR]. Records from \fIbridge\fR will be sent to
+each \fIip\fR on UDP \fIport\fR. The \fIip\fR must be specified
+numerically, not as a DNS name. If \Iport\fR is omitted, port 6343 is
+used.
+.PP
+By default, 1 out of every 400 packets is sent to the configured sFlow
+collector. To override this, set \fBsflow.\fIbridge\fB.sampling\fR to
+the number of switched packets out of which 1, on average, will be
+sent to the sFlow collector, e.g. a value of 1 sends every packet to
+the collector, a value of 2 sends 50% of the packets to the collector,
+and so on.
+.PP
+\fBovs\-vswitchd\fR also occasionally sends switch port statistics to
+sFlow collectors, by default every 30 seconds. To override this, set
+\fBsflow.\fIbridge\fB.polling\fR to a duration in seconds.
+.PP
+By default, \fBovs\-vswitchd\fR sends the first 128 bytes of sampled
+packets to sFlow collectors. To override this, set
+\fBsflow.\fIbridge\fB.header\fR to a size in bytes.