switch's tables are removed. See \fBFlow Syntax\fR, below, for the
syntax of \fIflows\fR.
.
-.TP
-\fBmonitor \fIswitch\fR [\fImiss-len\fR]
+.IP "\fBsnoop \fIswitch\fR"
+Connects to \fIswitch\fR and prints to the console all OpenFlow
+messages received. Unlike other \fBovs\-ofctl\fR commands, if
+\fIswitch\fR is the name of a bridge, then the \fBsnoop\fR command
+connects to a Unix domain socket named
+\fB@RUNDIR@/\fIbridge\fB.snoop\fR. \fBovs\-vswitchd\fR listens on
+such a socket for each bridge and sends to it all of the OpenFlow
+messages sent to or received from its configured OpenFlow controller.
+Thus, this command can be used to view OpenFlow protocol activity
+between a switch and its controller.
+.IP
+When a switch has more than one controller configured, only the
+traffic to and from a single controller is output. If none of the
+controllers is configured as a master or a slave (using a Nicira
+extension to OpenFlow), then a controller is chosen arbitrarily among
+them. If there is a master controller, it is chosen; otherwise, if
+there are any controllers that are not masters or slaves, one is
+chosen arbitrarily; otherwise, a slave controller is chosen
+arbitrarily. This choice is made once at connection time and does not
+change as controllers reconfigure their roles.
+.IP
+If a switch has no controller configured, or if
+the configured controller is disconnected, no traffic is sent, so
+monitoring will not show any traffic.
+.
+.IQ "\fBmonitor \fIswitch\fR [\fImiss-len\fR]"
Connects to \fIswitch\fR and prints to the console all OpenFlow
messages received. Usually, \fIswitch\fR should specify a connection
named on \fBovs\-openflowd\fR(8)'s \fB-l\fR or \fB--listen\fR command line
.IP
If \fImiss-len\fR is provided, \fBovs\-ofctl\fR sends an OpenFlow ``set
configuration'' message at connection setup time that requests
-\fImiss-len\fR bytes of each packet that misses the flow table. The
-OpenFlow reference implementation does not send these messages to the
+\fImiss-len\fR bytes of each packet that misses the flow table. Open vSwitch
+does not send these and other asynchronous messages to an
\fBovs\-ofctl monitor\fR client connection unless a nonzero value is
-specified on this argument.
+specified on this argument. (Thus, if \fImiss\-len\fR is not
+specified, very little traffic will ordinarily be printed.)
.IP
This command may be useful for debugging switch or controller
implementations.
Same as \fBdl_type=0x0806\fR.
.
.PP
-The \fBadd-flow\fR and \fBadd-flows\fR commands require an additional field:
+The \fBadd-flow\fR and \fBadd-flows\fR commands require an additional
+field, which must be the final field specified:
.
.IP \fBactions=\fR[\fItarget\fR][\fB,\fItarget\fR...]\fR
Specifies a comma-separated list of actions to take on a packet when the