[mirror_ovs.git] / OPENFLOW-1.1+

                OpenFlow 1.1+ support in Open vSwitch
                =====================================

Open vSwitch support for OpenFlow 1.1, 1.2, and 1.3 is a work in
progress.  This file describes the work still to be done.

The Plan
--------

OpenFlow version support is not a build-time option.  A single build
of Open vSwitch must be able to handle all supported versions of
OpenFlow.  Ideally, even at runtime it should be able to support all
protocol versions at the same time on different OpenFlow bridges (and
perhaps even on the same bridge).

At the same time, it would be a shame to litter the core of the OVS
code with lots of ugly code concerned with the details of various
OpenFlow protocol versions.

The primary approach to compatibility is to abstract most of the
details of the differences from the core code, by adding a protocol
layer that translates between OF1.x and a slightly higher-level
abstract representation.  The core of this approach is the many struct
ofputil_* structures in lib/ofp-util.h.

As a consequence of this approach, OVS cannot use OpenFlow protocol
definitions that closely resemble those in the OpenFlow specification,
because openflow.h in different versions of the OpenFlow specification
defines the same identifier with different values.  Instead,
openflow-common.h contains definitions that are common to all the
specifications and separate protocol version-specific headers contain
protocol-specific definitions renamed so as not to conflict,
e.g. OFPAT10_ENQUEUE and OFPAT11_ENQUEUE for the OpenFlow 1.0 and 1.1
values for OFPAT_ENQUEUE.  Generally, in cases of conflict, the
protocol layer will define a more abstract OFPUTIL_* or struct
ofputil_*.

Here are the current approaches in a few tricky areas:

    * Port numbering.  OpenFlow 1.0 has 16-bit port numbers and later
      OpenFlow versions have 32-bit port numbers.  For now, OVS
      support for later protocol versions requires all port numbers to
      fall into the 16-bit range, translating the reserved OFPP_* port
      numbers.

    * Actions.  OpenFlow 1.0 and later versions have very different
      ideas of actions.  OVS reconciles by translating all the
      versions' actions (and instructions) to and from a common
      internal representation.

OpenFlow 1.1
------------

The list of remaining work items for OpenFlow 1.1 is below.  It is
probably incomplete.

    * Implement Write-Actions instruction.
      [required for 1.1+]

    * The new in_phy_port field in OFPT_PACKET_IN needs some kind of
      implementation.  It has a sensible interpretation for tunnels
      but in general the physical port is not in the datapath for OVS
      so the value is not necessarily meaningful.  We might have to
      just fix it as the same as in_port.
      [required for OF1.1; optional for OF1.2+]

    * OFPT_TABLE_MOD message.  This is new in OF1.1, so we need to
      implement it.  It should be implemented so that the default OVS
      behavior does not change.
      [required for OF1.1 and OF1.2]

    * Flow table stats (OFPST_TABLE).

        * Reference count (active entries)
          [implemented]
          [required for OF1.1 and OF1.2]

        * Packet Lookups
          [required for OF1.1; optional for OF1.2]

        * Packet Matches
          [required for OF1.1; optional for OF1.2]

    * MPLS.  Simon Horman maintains a patch series that adds this
      feature.  This is partially merged.
      [optional for OF1.1+]

    * SCTP.  Joe Stringer maintains a patch series that adds this
      feature.  It has received review comments that need to be
      addressed before it is merged.
      [optional for OF1.1+]

    * Match and set double-tagged VLANs (QinQ).  This requires kernel
      work for reasonable performance.
      [optional for OF1.1+]

    * VLANs tagged with 88a8 Ethertype.  This requires kernel work for
      reasonable performance.
      [required for OF1.1+]

    * Groups.

        * Type all
          [required for OF1.1+]

        * Type select
          [optional for OF1.1+]

        * Type indirect
          [required for OF1.1+]

        * Type fast failover
          [optional for OF1.1+]

        * Statistics
          [optional for OF1.1+]

OpenFlow 1.2
------------

OpenFlow 1.2 support requires OpenFlow 1.1 as a prerequisite, plus the
following additional work.  (This is based on the change log at the
end of the OF1.2 spec.  I didn't compare the specs carefully yet.)

    * OFPT_FLOW_MOD:

        * New flag OFPFF_RESET_COUNTS.
          [required for OF1.2+]

        * Add ability to delete flow in all tables.
          [required for OF1.2+]

        * Update DESIGN to describe OF1.2 behavior also.
          [required for OF1.2+]

OpenFlow 1.3
------------

OpenFlow 1.3 support requires OpenFlow 1.2 as a prerequisite, plus the
following additional work.  (This is based on the change log at the
end of the OF1.3 spec, reusing most of the section titles directly.  I
didn't compare the specs carefully yet.)

    * Send errors for unsupported multipart requests.
      [required for OF1.3+]

    * Add support for multipart requests.
      [optional for OF1.3+]

    * Add OFPMP_TABLE_FEATURES statistics.
      [optional for OF1.3+]

    * More flexible table miss support.
      [required for OF1.3+]

    * IPv6 extension header handling support.  Fully implementing this
      requires kernel support.  This likely will take some careful and
      probably time-consuming design work.  The actual coding, once
      that is all done, is probably 2 or 3 days work.
      [optional for OF1.3+]

    * Per-flow meters.  Similar to IPv6 extension headers in kernel
      and design requirements.  Might be politically difficult to add
      directly to the kernel module, since its functionality overlaps
      with tc.  Ideally, therefore, we could implement these somehow
      with tc, but I haven't investigated whether that makes sense.
      [optional for OF1.3+]

    * Per-connection event filtering.  OF1.3 adopted Open vSwitch's
      existing design for this feature so implementation should be
      easy.
      [required for OF1.3+]

    * Auxiliary connections.  An implementation in generic code might
      be a week's worth of work.  The value of an implementation in
      generic code is questionable, though, since much of the benefit
      of axuiliary connections is supposed to be to take advantage of
      hardware support.  (We could make the kernel module somehow
      send packets across the auxiliary connections directly, for
      some kind of "hardware" support, if we judged it useful enough.)
      [optional for OF1.3+]

    * MPLS BoS matching.  (Included in Simon's MPLS series?)
      [optional for OF1.3+]

    * Provider Backbone Bridge tagging.  I don't plan to implement
      this (but we'd accept an implementation).
      [optional for OF1.3+]

    * Rework tag order.  I'm not sure whether we need to do anything
      for this. Part of MPLS patchset by Simon Horman.
      [required for v1.3+]

    * On-demand flow counters.  I think this might be a real
      optimization in some cases for the software switch.
      [optional for OF1.3+]

    * Duration Statistics
      - New for Per Port, Per Queue, Per Group
      [required for v1.3+]

How to contribute
-----------------

If you plan to contribute code for a feature, please let everyone know
on ovs-dev before you start work.  This will help avoid duplicating
work.

Please consider the following:

    * Testing.  Please test your code.

    * Unit tests.  Please consider writing some.  The tests directory
      has many examples that you can use as a starting point.

    * ovs-ofctl.  If you add a feature that is useful for some
      ovs-ofctl command then you should add support for it there.

    * Documentation.  If you add a user-visible feature, then you
      should document it in the appropriate manpage and mention it in
      NEWS as well.

    * Coding style (see the CodingStyle file at the top of the source
      tree).

    * The patch submission guidelines (see SubmittingPatches).  I
      recommend using "git send-email", which automatically follows a
      lot of those guidelines.

Bug Reporting
-------------

Please report problems to bugs@openvswitch.org.
Commit	Line	Data
bea97716 BP	1	OpenFlow 1.1+ support in Open vSwitch
	2	=====================================
	3
	4	Open vSwitch support for OpenFlow 1.1, 1.2, and 1.3 is a work in
	5	progress. This file describes the work still to be done.
	6
	7	The Plan
	8	--------
	9
	10	OpenFlow version support is not a build-time option. A single build
	11	of Open vSwitch must be able to handle all supported versions of
	12	OpenFlow. Ideally, even at runtime it should be able to support all
	13	protocol versions at the same time on different OpenFlow bridges (and
	14	perhaps even on the same bridge).
	15
	16	At the same time, it would be a shame to litter the core of the OVS
	17	code with lots of ugly code concerned with the details of various
	18	OpenFlow protocol versions.
	19
	20	The primary approach to compatibility is to abstract most of the
	21	details of the differences from the core code, by adding a protocol
	22	layer that translates between OF1.x and a slightly higher-level
	23	abstract representation. The core of this approach is the many struct
	24	ofputil_* structures in lib/ofp-util.h.
	25
	26	As a consequence of this approach, OVS cannot use OpenFlow protocol
	27	definitions that closely resemble those in the OpenFlow specification,
	28	because openflow.h in different versions of the OpenFlow specification
	29	defines the same identifier with different values. Instead,
	30	openflow-common.h contains definitions that are common to all the
	31	specifications and separate protocol version-specific headers contain
	32	protocol-specific definitions renamed so as not to conflict,
	33	e.g. OFPAT10_ENQUEUE and OFPAT11_ENQUEUE for the OpenFlow 1.0 and 1.1
	34	values for OFPAT_ENQUEUE. Generally, in cases of conflict, the
	35	protocol layer will define a more abstract OFPUTIL_* or struct
	36	ofputil_*.
	37
	38	Here are the current approaches in a few tricky areas:
	39
	40	* Port numbering. OpenFlow 1.0 has 16-bit port numbers and later
	41	OpenFlow versions have 32-bit port numbers. For now, OVS
	42	support for later protocol versions requires all port numbers to
	43	fall into the 16-bit range, translating the reserved OFPP_* port
	44	numbers.
	45
	46	* Actions. OpenFlow 1.0 and later versions have very different
	47	ideas of actions. OVS reconciles by translating all the
	48	versions' actions (and instructions) to and from a common
	49	internal representation.
	50
	51	OpenFlow 1.1
	52	------------
	53
	54	The list of remaining work items for OpenFlow 1.1 is below. It is
	55	probably incomplete.
	56
	57	* Implement Write-Actions instruction.
4db3f50a	58	[required for 1.1+]
bea97716 BP	59
	60	* The new in_phy_port field in OFPT_PACKET_IN needs some kind of
	61	implementation. It has a sensible interpretation for tunnels
	62	but in general the physical port is not in the datapath for OVS
	63	so the value is not necessarily meaningful. We might have to
	64	just fix it as the same as in_port.
4db3f50a	65	[required for OF1.1; optional for OF1.2+]
bea97716	66
4db3f50a	67	* OFPT_TABLE_MOD message. This is new in OF1.1, so we need to
bea97716 BP	68	implement it. It should be implemented so that the default OVS
bea97716 BP	69	behavior does not change.
4db3f50a SH	70	[required for OF1.1 and OF1.2]
	71
	72	* Flow table stats (OFPST_TABLE).
	73
	74	* Reference count (active entries)
	75	[implemented]
	76	[required for OF1.1 and OF1.2]
	77
	78	* Packet Lookups
	79	[required for OF1.1; optional for OF1.2]
	80
	81	* Packet Matches
	82	[required for OF1.1; optional for OF1.2]
bea97716	83
bea97716	84	* MPLS. Simon Horman maintains a patch series that adds this
ac3d64b1	85	feature. This is partially merged.
4db3f50a	86	[optional for OF1.1+]
bea97716 BP	87
	88	* SCTP. Joe Stringer maintains a patch series that adds this
	89	feature. It has received review comments that need to be
	90	addressed before it is merged.
4db3f50a	91	[optional for OF1.1+]
bea97716 BP	92
	93	* Match and set double-tagged VLANs (QinQ). This requires kernel
	94	work for reasonable performance.
4db3f50a	95	[optional for OF1.1+]
bea97716 BP	96
	97	* VLANs tagged with 88a8 Ethertype. This requires kernel work for
	98	reasonable performance.
4db3f50a	99	[required for OF1.1+]
bea97716 BP	100
	101	* Groups.
	102
4db3f50a SH	103	* Type all
	104	[required for OF1.1+]
	105
	106	* Type select
	107	[optional for OF1.1+]
	108
	109	* Type indirect
	110	[required for OF1.1+]
	111
	112	* Type fast failover
	113	[optional for OF1.1+]
	114
	115	* Statistics
	116	[optional for OF1.1+]
	117
bea97716 BP	118	OpenFlow 1.2
	119	------------
	120
	121	OpenFlow 1.2 support requires OpenFlow 1.1 as a prerequisite, plus the
	122	following additional work. (This is based on the change log at the
b2c9b585	123	end of the OF1.2 spec. I didn't compare the specs carefully yet.)
bea97716	124
bea97716 BP	125	* OFPT_FLOW_MOD:
bea97716 BP	126
bea97716	127	* New flag OFPFF_RESET_COUNTS.
4db3f50a	128	[required for OF1.2+]
bea97716	129
bea97716	130	* Add ability to delete flow in all tables.
4db3f50a	131	[required for OF1.2+]
bea97716 BP	132
bea97716 BP	133	* Update DESIGN to describe OF1.2 behavior also.
4db3f50a	134	[required for OF1.2+]
bea97716	135
bea97716 BP	136	OpenFlow 1.3
	137	------------
	138
	139	OpenFlow 1.3 support requires OpenFlow 1.2 as a prerequisite, plus the
	140	following additional work. (This is based on the change log at the
	141	end of the OF1.3 spec, reusing most of the section titles directly. I
b2c9b585	142	didn't compare the specs carefully yet.)
bea97716	143
4db3f50a SH	144	* Send errors for unsupported multipart requests.
	145	[required for OF1.3+]
	146
bea97716	147	* Add support for multipart requests.
4db3f50a	148	[optional for OF1.3+]
bea97716 BP	149
bea97716 BP	150	* Add OFPMP_TABLE_FEATURES statistics.
4db3f50a	151	[optional for OF1.3+]
bea97716 BP	152
bea97716 BP	153	* More flexible table miss support.
4db3f50a	154	[required for OF1.3+]
bea97716 BP	155
	156	* IPv6 extension header handling support. Fully implementing this
	157	requires kernel support. This likely will take some careful and
	158	probably time-consuming design work. The actual coding, once
	159	that is all done, is probably 2 or 3 days work.
4db3f50a	160	[optional for OF1.3+]
bea97716 BP	161
	162	* Per-flow meters. Similar to IPv6 extension headers in kernel
	163	and design requirements. Might be politically difficult to add
	164	directly to the kernel module, since its functionality overlaps
	165	with tc. Ideally, therefore, we could implement these somehow
b2c9b585	166	with tc, but I haven't investigated whether that makes sense.
4db3f50a	167	[optional for OF1.3+]
bea97716	168
ac3d64b1	169	* Per-connection event filtering. OF1.3 adopted Open vSwitch's
bea97716 BP	170	existing design for this feature so implementation should be
bea97716 BP	171	easy.
4db3f50a	172	[required for OF1.3+]
bea97716	173
4db3f50a SH	174	* Auxiliary connections. An implementation in generic code might
	175	be a week's worth of work. The value of an implementation in
	176	generic code is questionable, though, since much of the benefit
	177	of axuiliary connections is supposed to be to take advantage of
	178	hardware support. (We could make the kernel module somehow
	179	send packets across the auxiliary connections directly, for
	180	some kind of "hardware" support, if we judged it useful enough.)
	181	[optional for OF1.3+]
bea97716 BP	182
bea97716 BP	183	* MPLS BoS matching. (Included in Simon's MPLS series?)
4db3f50a	184	[optional for OF1.3+]
bea97716	185
b2c9b585 BP	186	* Provider Backbone Bridge tagging. I don't plan to implement
b2c9b585 BP	187	this (but we'd accept an implementation).
4db3f50a	188	[optional for OF1.3+]
bea97716	189
b2c9b585	190	* Rework tag order. I'm not sure whether we need to do anything
4db3f50a SH	191	for this. Part of MPLS patchset by Simon Horman.
4db3f50a SH	192	[required for v1.3+]
bea97716	193
bea97716 BP	194	* On-demand flow counters. I think this might be a real
bea97716 BP	195	optimization in some cases for the software switch.
4db3f50a SH	196	[optional for OF1.3+]
	197
	198	* Duration Statistics
	199	- New for Per Port, Per Queue, Per Group
	200	[required for v1.3+]
bea97716 BP	201
	202	How to contribute
	203	-----------------
	204
	205	If you plan to contribute code for a feature, please let everyone know
	206	on ovs-dev before you start work. This will help avoid duplicating
	207	work.
	208
	209	Please consider the following:
	210
	211	* Testing. Please test your code.
	212
	213	* Unit tests. Please consider writing some. The tests directory
	214	has many examples that you can use as a starting point.
	215
	216	* ovs-ofctl. If you add a feature that is useful for some
	217	ovs-ofctl command then you should add support for it there.
	218
	219	* Documentation. If you add a user-visible feature, then you
	220	should document it in the appropriate manpage and mention it in
	221	NEWS as well.
	222
	223	* Coding style (see the CodingStyle file at the top of the source
	224	tree).
	225
	226	* The patch submission guidelines (see SubmittingPatches). I
b2c9b585	227	recommend using "git send-email", which automatically follows a
bea97716 BP	228	lot of those guidelines.
	229
	230	Bug Reporting
	231	-------------
	232
	233	Please report problems to bugs@openvswitch.org.