1 OpenFlow 1.1+ support in Open vSwitch
2 =====================================
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.
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).
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.
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.
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
38 Here are the current approaches in a few tricky areas:
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
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.
54 The list of remaining work items for OpenFlow 1.1 is below. It is
57 * The new in_phy_port field in OFPT_PACKET_IN needs some kind of
58 implementation. It has a sensible interpretation for tunnels
59 but in general the physical port is not in the datapath for OVS
60 so the value is not necessarily meaningful. We might have to
61 just fix it as the same as in_port.
62 [required for OF1.1; optional for OF1.2+]
64 * OFPT_TABLE_MOD message. This is new in OF1.1, so we need to
65 implement it. It should be implemented so that the default OVS
66 behavior does not change.
67 [required for OF1.1 and OF1.2]
69 * MPLS. Simon Horman maintains a patch series that adds this
70 feature. This is partially merged.
73 * Match and set double-tagged VLANs (QinQ). This requires kernel
74 work for reasonable performance.
77 * VLANs tagged with 88a8 Ethertype. This requires kernel work for
78 reasonable performance.
101 OpenFlow 1.2 support requires OpenFlow 1.1 as a prerequisite. All the
102 additional work specific to Openflow 1.2 are complete. (This is based
103 on the change log at the end of the OF1.2 spec. I didn't compare the
104 specs carefully yet.)
106 * Action translation needs some work to transform OpenFlow 1.1
107 field modification actions into OpenFlow 1.2+ "set-field"
108 actions, because OpenFlow 1.2 dropped support for the OF1.1
114 OpenFlow 1.3 support requires OpenFlow 1.2 as a prerequisite, plus the
115 following additional work. (This is based on the change log at the
116 end of the OF1.3 spec, reusing most of the section titles directly. I
117 didn't compare the specs carefully yet.)
119 * Send errors for unsupported multipart requests.
120 [required for OF1.3+]
122 * Add support for multipart requests.
123 [optional for OF1.3+]
125 * Add OFPMP_TABLE_FEATURES statistics.
126 [optional for OF1.3+]
128 * More flexible table miss support.
129 This requires the following.
130 - Change the default table-miss action (in the absense of table-miss
131 entry) from packet_in to drop for OF1.3+. Decide what to do if
132 a switch is configured to support multiple OF versions.
133 - Distinguish table-miss flow entry and make its packet_in reason
134 OFPR_NO_MATCH. (OFPR_TABLE_MISS for OF1.4)
135 Also, make it use the appropriate pin scheduler.
136 [required for OF1.3+]
138 * IPv6 extension header handling support. Fully implementing this
139 requires kernel support. This likely will take some careful and
140 probably time-consuming design work. The actual coding, once
141 that is all done, is probably 2 or 3 days work.
142 [optional for OF1.3+]
144 * Per-flow meters. Similar to IPv6 extension headers in kernel
145 and design requirements. Might be politically difficult to add
146 directly to the kernel module, since its functionality overlaps
147 with tc. Ideally, therefore, we could implement these somehow
148 with tc, but I haven't investigated whether that makes sense.
149 [optional for OF1.3+]
151 * Per-connection event filtering. OF1.3 adopted Open vSwitch's
152 existing design for this feature so implementation should be
154 [required for OF1.3+]
156 * Auxiliary connections. An implementation in generic code might
157 be a week's worth of work. The value of an implementation in
158 generic code is questionable, though, since much of the benefit
159 of axuiliary connections is supposed to be to take advantage of
160 hardware support. (We could make the kernel module somehow
161 send packets across the auxiliary connections directly, for
162 some kind of "hardware" support, if we judged it useful enough.)
163 [optional for OF1.3+]
165 * MPLS BoS matching. (Included in Simon's MPLS series?)
166 [optional for OF1.3+]
168 * Provider Backbone Bridge tagging. I don't plan to implement
169 this (but we'd accept an implementation).
170 [optional for OF1.3+]
172 * Rework tag order. I'm not sure whether we need to do anything
173 for this. Part of MPLS patchset by Simon Horman.
176 * On-demand flow counters. I think this might be a real
177 optimization in some cases for the software switch.
178 [optional for OF1.3+]
180 ONF OpenFlow Exensions for 1.3.X Pack1
181 --------------------------------------
183 OpenFlow 1.3 has a bunch of ONF extentions.
184 Many of them are necessary for OpenFlow 1.4 as well.
186 * Flow entry notifications
187 This seems to be modelled after OVS's NXST_FLOW_MONITOR.
189 [required for OF1.4+]
193 [required for OF1.4+]
195 * Flow entry eviction
196 OVS has flow eviction functionality.
197 table_mod OFPTC_EVICTION, flow_mod 'importance', and
198 table_desc ofp_table_mod_prop_eviction need to be implemented.
200 [optional for OF1.4+]
204 [optional for OF1.4+]
207 Transactional modification. OpenFlow 1.4 requires to support
208 flow_mods and port_mods in a bundle.
209 (Not related to OVS's 'ofbundle' stuff.)
211 [required for OF1.4+]
213 * Table synchronisation
215 [optional for OF1.4+]
217 * Group notifications
219 [optional for OF1.4+]
221 * Bad flow entry priority error
222 Probably not so useful to the software switch.
224 [optional for OF1.4+]
226 * Set async config error
228 [optional for OF1.4+]
230 * PBB UCA header field
232 [optional for OF1.4+]
234 * Duplicate instruction error
235 We already have ONFBIC_DUP_INSTRUCTION.
237 [required for OF1.4+]
239 * Multipart timeout error
241 [required for OF1.4+]
246 * More extensible wire protocol
247 Many on-wire structures got TLVs.
249 [required for OF1.4+]
251 * More descriptive reasons for packet-in
252 Distinguish OFPR_APPLY_ACTION, OFPR_ACTION_SET, OFPR_GROUP,
253 OFPR_PACKET_OUT. NO_MATCH was renamed to OFPR_TABLE_MISS.
255 [required for OF1.4+]
257 * Optical port properties
259 [optional for OF1.4+]
261 * Flow-removed reason for meter delete
262 Report flow removal due to meter deletion with OFPRR_METER_DELETE.
264 [optional for OF1.4+]
266 * Meter notifications
268 [optional for OF1.4+]
273 If you plan to contribute code for a feature, please let everyone know
274 on ovs-dev before you start work. This will help avoid duplicating
277 Please consider the following:
279 * Testing. Please test your code.
281 * Unit tests. Please consider writing some. The tests directory
282 has many examples that you can use as a starting point.
284 * ovs-ofctl. If you add a feature that is useful for some
285 ovs-ofctl command then you should add support for it there.
287 * Documentation. If you add a user-visible feature, then you
288 should document it in the appropriate manpage and mention it in
291 * Coding style (see the CodingStyle file at the top of the source
294 * The patch submission guidelines (see SubmittingPatches). I
295 recommend using "git send-email", which automatically follows a
296 lot of those guidelines.
301 Please report problems to bugs@openvswitch.org.