+The following field assignments require support for the NXM (Nicira
+Extended Match) extension to OpenFlow. When one of these 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.
+.
+.IP \fBarp_sha=\fIxx\fB:\fIxx\fB:\fIxx\fB:\fIxx\fB:\fIxx\fB:\fIxx\fR
+.IQ \fBarp_tha=\fIxx\fB:\fIxx\fB:\fIxx\fB:\fIxx\fB:\fIxx\fB:\fIxx\fR
+When \fBdl_type\fR specifies ARP, \fBarp_sha\fR and \fBarp_tha\fR match
+the source and target hardware address, respectively. An address is
+specified as 6 pairs of hexadecimal digits delimited by colons.
+.
+.IP \fBipv6_src=\fIipv6\fR[\fB/\fInetmask\fR]
+.IQ \fBipv6_dst=\fIipv6\fR[\fB/\fInetmask\fR]
+When \fBdl_type\fR is 0x86dd (possibly via shorthand, e.g., \fBipv6\fR
+or \fBtcp6\fR), matches IPv6 source (or destination) address \fIipv6\fR,
+which may be specified as defined in RFC 2373. The preferred format is
+\fIx\fB:\fIx\fB:\fIx\fB:\fIx\fB:\fIx\fB:\fIx\fB:\fIx\fB:\fIx\fR, where
+\fIx\fR are the hexadecimal values of the eight 16-bit pieces of the
+address. A single instance of \fB::\fR may be used to indicate multiple
+groups of 16-bits of zeros. The optional \fInetmask\fR allows
+restricting a match to an IPv6 address prefix. A netmask is specified
+as a CIDR block (e.g. \fB2001:db8:3c4d:1::/64\fR).
+.
+.IP \fBnd_target=\fIipv6\fR
+When \fBdl_type\fR, \fBnw_proto\fR, and \fBicmp_type\fR specify
+IPv6 Neighbor Discovery (ICMPv6 type 135 or 136), matches the target address
+\fIipv6\fR. \fIipv6\fR is in the same format described earlier for the
+\fBipv6_src\fR and \fBipv6_dst\fR fields.
+.
+.IP \fBnd_sll=\fIxx\fB:\fIxx\fB:\fIxx\fB:\fIxx\fB:\fIxx\fB:\fIxx\fR
+When \fBdl_type\fR, \fBnw_proto\fR, and \fBicmp_type\fR specify IPv6
+Neighbor Solicitation (ICMPv6 type 135), matches the source link\-layer
+address option. An address is specified as 6 pairs of hexadecimal
+digits delimited by colons.
+.
+.IP \fBnd_tll=\fIxx\fB:\fIxx\fB:\fIxx\fB:\fIxx\fB:\fIxx\fB:\fIxx\fR
+When \fBdl_type\fR, \fBnw_proto\fR, and \fBicmp_type\fR specify IPv6
+Neighbor Advertisement (ICMPv6 type 136), matches the target link\-layer
+address option. An address is specified as 6 pairs of hexadecimal
+digits delimited by colons.
+.
+.IP \fBtun_id=\fItunnel-id\fR[\fB/\fImask\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. If \fImask\fR is omitted,
+\fItunnel-id\fR is the exact tunnel ID to match; if \fImask\fR is
+specified, then a 1-bit in \fImask\fR indicates that the corresponding
+bit in \fItunnel-id\fR must match exactly, and a 0-bit wildcards that
+bit.
+.IP
+In an attempt to be compatible with more switches, \fBovs\-ofctl\fR will
+prefer to use the ``tunnel ID from cookie'' Nicira extension to NXM.
+The use of this extension comes with three caveats: the top 32 bits of
+the \fBcookie\fR (see below) are used for \fItunnel-id\fR and thus
+unavailable for other use, specifying \fBtun_id\fR on \fBdump\-flows\fR
+or \fBdump\-aggregate\fR has no effect, and \fImask\fR is not supported.
+If any of these caveats apply, \fBovs-ofctl\fR will use NXM.
+.
+.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.
+.
+.PP
+Defining IPv6 flows (those with \fBdl_type\fR equal to 0x86dd) requires
+support for NXM. The following shorthand notations are available for
+IPv6-related flows:
+.
+.IP \fBipv6\fR
+Same as \fBdl_type=0x86dd\fR.
+.
+.IP \fBtcp6\fR
+Same as \fBdl_type=0x86dd,nw_proto=6\fR.
+.
+.IP \fBudp6\fR
+Same as \fBdl_type=0x86dd,nw_proto=17\fR.
+.
+.IP \fBicmp6\fR
+Same as \fBdl_type=0x86dd,nw_proto=58\fR.
+.
+.PP
+The \fBadd\-flow\fR and \fBadd\-flows\fR commands require an additional