These actions modify packet data and metadata fields.
The set_field and load actions
Syntax:
set_field:value[/mask]->dst
load:value->dst
These actions loads a literal value into a field or part of a
field. The set_field action takes value in the customary syntax
for field dst, e.g. 00:11:22:33:44:55 for an Ethernet address,
and dst as the field's name. The optional mask allows part of a
field to be set.
The load action takes value as an integer value (in decimal or
prefixed by 0x for hexadecimal) and dst as a field or subfield in
the syntax described under ``Field Specifications'' above.
The following all set the Ethernet source address to
00:11:22:33:44:55:
• set_field:00:11:22:33:44:55->eth_src
• load:0x001122334455->eth_src
• load:0x001122334455->OXM_OF_ETH_SRC[]
The following all set the multicast bit in the Ethernet
destination address:
• set_field:01:00:00:00:00:00/01:00:00:00:00:00->eth_dst
• load:1->eth_dst[40]
Open vSwitch prohibits a set_field or load action whose dst is
not guaranteed to be part of the packet; for example, set_field
of nw_dst is only allowed in a flow that matches on Ethernet type
0x800. In some cases, such as in an action set, Open vSwitch
can't statically check that dst is part of the packet, and in
that case if it is not then Open vSwitch treats the action as a
no-op.
Conformance:
Open vSwitch 1.1 introduced NXAST_REG_LOAD as a extension to
OpenFlow 1.0 and used load to express it. Later, OpenFlow 1.2
introduced a standard OFPAT_SET_FIELD action that was restricted
to loading entire fields, so Open vSwitch added the form
set_field with this restriction. OpenFlow 1.5 extended
OFPAT_SET_FIELD to the point that it became a superset of
NXAST_REG_LOAD. Open vSwitch translates either syntax as
necessary for the OpenFlow version in use: in OpenFlow 1.0 and
1.1, NXAST_REG_LOAD; in OpenFlow 1.2, 1.3, and 1.4,
NXAST_REG_LOAD for load or for loading a subfield,
OFPAT_SET_FIELD otherwise; and OpenFlow 1.5 and later,
OFPAT_SET_FIELD.
The move action
Syntax:
move:src->dst
Copies the named bits from field or subfield src to field or
subfield dst. src and dst should fields or subfields in the
syntax described under ``Field Specifications'' above. The two
fields or subfields must have the same width.
Examples:
• move:reg0[0..5]->reg1[26..31] copies the six bits
numbered 0 through 5 in register 0 into bits 26
through 31 of register 1.
• move:reg0[0..15]->vlan_tci copies the least
significant 16 bits of register 0 into the VLAN TCI
field.
Conformance:
In OpenFlow 1.0 through 1.4, move ordinarily uses an Open vSwitch
extension to OpenFlow. In OpenFlow 1.5, move uses the OpenFlow
1.5 standard OFPAT_COPY_FIELD action. The ONF has also made
OFPAT_COPY_FIELD available as an extension to OpenFlow 1.3. Open
vSwitch 2.4 and later understands this extension and uses it if a
controller uses it, but for backward compatibility with older
versions of Open vSwitch, ovs-ofctl does not use it.
The mod_dl_src and mod_dl_dst actions
Syntax:
mod_dl_src:mac
mod_dl_dst:mac
Sets the Ethernet source or destination address, respectively, to
mac, which should be expressed in the form xx:xx:xx:xx:xx:xx.
For L3-only packets, that is, those that lack an Ethernet header,
this action has no effect.
Conformance:
OpenFlow 1.0 and 1.1 have specialized actions for these purposes.
OpenFlow 1.2 and later do not, so Open vSwitch translates them to
appropriate OFPAT_SET_FIELD actions for those versions,
The mod_nw_src and mod_nw_dst actions
Syntax:
mod_nw_src:ip
mod_nw_dst:ip
Sets the IPv4 source or destination address, respectively, to ip,
which should be expressed in the form w.x.y.z.
In OpenFlow 1.1 and later, consistency rules allow these actions
only in a flow that matches only packets that contain an IPv4
header (or following an action that adds an IPv4 header, e.g.
pop_mpls:0x0800). See ``Inconsistencies'', above, for more
information.
Conformance:
OpenFlow 1.0 and 1.1 have specialized actions for these purposes.
OpenFlow 1.2 and later do not, so Open vSwitch translates them to
appropriate OFPAT_SET_FIELD actions for those versions,
The mod_nw_tos and mod_nw_ecn actions
Syntax:
mod_nw_tos:tos
mod_nw_ecn:ecn
The mod_nw_tos action sets the DSCP bits in the IPv4 ToS/DSCP or
IPv6 traffic class field to tos, which must be a multiple of 4
between 0 and 255. This action does not modify the two least
significant bits of the ToS field (the ECN bits).
The mod_nw_ecn action sets the ECN bits in the IPv4 ToS or IPv6
traffic class field to ecn, which must be a value between 0 and
3, inclusive. This action does not modify the six most
significant bits of the field (the DSCP bits).
In OpenFlow 1.1 and later, consistency rules allow these actions
only in a flow that matches only packets that contain an IPv4 or
IPv6 header (or following an action that adds such a header). See
``Inconsistencies'', above, for more information.
Conformance:
OpenFlow 1.0 has a mod_nw_tos action but not mod_nw_ecn. Open
vSwitch implements the latter in OpenFlow 1.0 as an extension
using NXAST_REG_LOAD. OpenFlow 1.1 has specialized actions for
these purposes. OpenFlow 1.2 and later do not, so Open vSwitch
translates them to appropriate OFPAT_SET_FIELD actions for those
versions,
The mod_tp_src and mod_tp_dst actions
Syntax:
mod_tp_src:port
mod_tp_dst:port
Sets the TCP or UDP or SCTP source or destination port,
respectively, to port. Both IPv4 and IPv6 are supported.
In OpenFlow 1.1 and later, consistency rules allow these actions
only in a flow that matches only packets that contain a TCP or
UDP or SCTP header. See ``Inconsistencies'', above, for more
information.
Conformance:
OpenFlow 1.0 and 1.1 have specialized actions for these purposes.
OpenFlow 1.2 and later do not, so Open vSwitch translates them to
appropriate OFPAT_SET_FIELD actions for those versions,
The dec_ttl action
Syntax:
dec_ttl
dec_ttl(id1, [id2]...)
Decrement TTL of IPv4 packet or hop limit of IPv6 packet. If the
TTL or hop limit is initially 0 or 1, no decrement occurs, as
packets reaching TTL zero must be rejected. Instead, Open vSwitch
sends a ``packet-in'' message with reason code OFPR_INVALID_TTL
to each connected controller that has enabled receiving such
messages, and stops processing the current set of actions.
(However, if the current set of actions was reached through
resubmit, the remaining actions in outer levels resume
processing.)
As an Open vSwitch extension to OpenFlow, this action supports
the ability to specify a list of controller IDs. Open vSwitch
will only send the message to controllers with the given ID or
IDs. Specifying no list is equivalent to specifying a single
controller ID of zero.
Sets the TCP or UDP or SCTP source or destination port,
respectively, to port. Both IPv4 and IPv6 are supported.
In OpenFlow 1.1 and later, consistency rules allow these actions
only in a flow that matches only packets that contain an IPv4 or
IPv6 header. See ``Inconsistencies'', above, for more
information.
Conformance:
All versions of OpenFlow and Open vSwitch support this action.
The set_mpls_label, set_mpls_tc, and set_mpls_ttl actions
Syntax:
set_mpls_label:label
set_mpls_tc:tc
set_mpls_ttl:ttl
The set_mpls_label action sets the label of the packet's outer
MPLS label stack entry. label should be a 20-bit value that is
decimal by default; use a 0x prefix to specify the value in
hexadecimal.
The set_mpls_tc action sets the traffic class of the packet's
outer MPLS label stack entry. tc should be in the range 0 to 7,
inclusive.
The set_mpls_ttl action sets the TTL of the packet's outer MPLS
label stack entry. ttl should be in the range 0 to 255 inclusive.
In OpenFlow 1.1 and later, consistency rules allow these actions
only in a flow that matches only packets that contain an MPLS
label (or following an action that adds an MPLS label, e.g.
push_mpls:0x8847). See ``Inconsistencies'', above, for more
information.
Conformance:
OpenFlow 1.0 does not support MPLS, but Open vSwitch implements
these actions as extensions. OpenFlow 1.1 has specialized actions
for these purposes. OpenFlow 1.2 and later do not, so Open
vSwitch translates them to appropriate OFPAT_SET_FIELD actions
for those versions,
The dec_mpls_ttl and dec_nsh_ttl actions
Syntax:
dec_mpls_ttl
dec_nsh_ttl
These actions decrement the TTL of the packet's outer MPLS label
stack entry or its NSH header, respectively. If the TTL is
initially 0 or 1, no decrement occurs. Instead, Open vSwitch
sends a ``packet-in'' message with reason code BOFPR_INVALID_TTL
to OpenFlow controllers with ID 0, if it has enabled receiving
them. Processing the current set of actions then stops. (However,
if the current set of actions was reached through resubmit,
remaining actions in outer levels resume processing.)
In OpenFlow 1.1 and later, consistency rules allow this actions
only in a flow that matches only packets that contain an MPLS
label or an NSH header, respectively. See ``Inconsistencies'',
above, for more information.
Conformance:
Open vSwitch 1.11 introduced support for MPLS. OpenFlow 1.1 and
later support dec_mpls_ttl. Open vSwitch implements dec_mpls_ttl
as an extension to OpenFlow 1.0.
Open vSwitch 2.8 introduced support for NSH, although the NSH
draft changed after release so that only Open vSwitch 2.9 and
later conform to the final protocol specification. The
dec_nsh_ttl action and NSH support in general is an Open vSwitch
extension not supported by any version of OpenFlow.
The check_pkt_larger action
Syntax:
check_pkt_larger(pkt_len)->dst
Checks if the packet is larger than the specified length in
pkt_len. If so, stores 1 in dst, which should be a 1-bit field;
if not, stores 0.
The packet length to check against the argument pkt_len includes
the L2 header and L2 payload of the packet, but not the VLAN tag
(if present).
Examples:
• check_pkt_larger(1500)->reg0[0]
• check_pkt_larger(8000)->reg9[10]
This action was added in Open vSwitch 2.11.90.
The delete_field action
Syntax:
delete_field:field
The delete_field action deletes a field in the syntax described
under ``Field Specifications'' above. Currently, only the
tun_metadta fields are supported.
This action was added in Open vSwitch 2.13.90.
