.IP
When \fBdl_type\fR and \fBnw_proto\fR take other values, the values of
these settings are ignored (see \fBFlow Syntax\fR above).
+.IP \fBtun_id=\fItunnel\-id\fR
+Matches tunnel identifier \fItunnel\-id\fR. Only packets that arrive
+over a tunnel that carries a key (e.g. GRE with the RFC 2890 key
+extension) will have a nonzero tunnel ID.
+.IP
+\fBtun_id\fR requires use of one of two Nicira extensions to OpenFlow:
+.RS
+.IP "NXM (Nicira Extended Match)"
+This extension fully supports \fBtun_id\fR.
+.IP "Tunnel ID from Cookie"
+This extension supports \fBtun_id\fR with two caveats: the top 32 bits
+of the \fBcookie\fR (see below) are used for \fItunnel\-id\fR and thus
+unavailable for other use, and specifying \fBtun_id\fR on
+\fBdump\-flows\fR or \fBdump\-aggregate\fR has no effect.
+.RE
+.IP
+When \fBtun_id\fR is specified, \fBovs\-ofctl\fR will automatically
+attempt to negotiate use of one of these extensions. It will use the
+``tunnel ID from cookie'' extension if neither caveat applies and NXM
+otherwise. If the switch does not support the needed extension, then
+\fBovs\-ofctl\fR will report a fatal error.
+.IP "\fBreg\fIidx\fB=\fIvalue\fR[\fB/\fImask\fR]"
+Matches \fIvalue\fR either exactly or with optional \fImask\fR in
+register number \fIidx\fR. The valid range of \fIidx\fR depends on
+the switch. \fIvalue\fR and \fImask\fR are 32-bit integers, by
+default in decimal (use a \fB0x\fR prefix to specify hexadecimal).
+Arbitrary \fImask\fR values are allowed: a 1-bit in \fImask\fR
+indicates that the corresponding bit in \fIvalue\fR must match
+exactly, and a 0-bit wildcards that bit.
+.IP
+When a packet enters an OpenFlow switch, all of the registers are set
+to 0. Only explicit Nicira extension actions change register values.
+.IP
+Register matches require support for the NXM (Nicira Extended Match)
+extension to OpenFlow. When a register match is specified,
+\fBovs\-ofctl\fR will automatically attempt to negotiate use of this
+extension. If the switch does not support NXM, then \fBovs\-ofctl\fR
+will report a fatal error.
.
.PP
The following shorthand notations are also available:
\fB\-\-strict\fR
Uses strict matching when running flow modification commands.
.
+.IP "\fB\-F \fIformat\fR"
+.IQ "\fB\-\-flow\-format=\fIformat\fR"
+\fBovs\-ofctl\fR supports the following flow formats, in order of
+increasing capability:
+.RS
+.IP "\fBopenflow10\fR"
+This is the standard OpenFlow 1.0 flow format. It should be supported
+by all OpenFlow switches.
+.
+.IP "\fBtun_id_from_cookie\fR"
+This Nicira extension to OpenFlow adds minimal and limited support for
+\fBtun_id\fR, but it does not support any other Nicira flow
+extensions. (This flow format is deprecated.)
+.
+.IP "\fBnxm\fR (Nicira Extended Match)"
+This Nicira extension to OpenFlow is flexible and extensible. It
+supports all of the Nicira flow extensions, such as \fBtun_id\fR and
+registers.
+.RE
+.IP
+Usually, \fBovs\-ofctl\fR picks the correct format automatically. For
+commands that modify the flow table, \fBovs\-ofctl\fR by default uses
+the most widely supported flow format that supports the flows being
+added. For commands that query the flow table, \fBovs\-ofctl\fR by
+default queries and uses the most advanced format supported by the
+switch.
+.IP
+This option, where \fIformat\fR is one of the formats listed in the
+above table, overrides \fBovs\-ofctl\fR's default choice of flow
+format. If a command cannot work as requested using the requested
+flow format, \fBovs\-ofctl\fR will report a fatal error.
+.
+.IP "\fB\-m\fR"
+.IQ "\fB\-\-more\fR"
+Increases the verbosity of OpenFlow messages printed and logged by
+\fBovs\-ofctl\fR commands. Specify this option more than once to
+increase verbosity further.
.SS "Public Key Infrastructure Options"
.so lib/ssl.man
.so lib/vlog.man