OPENFLOW-1.1+

   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     * 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+]
  63
  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]
  68
  69     * MPLS.  Simon Horman maintains a patch series that adds this
  70       feature.  This is partially merged.
  71       [optional for OF1.1+]
  72
  73     * Match and set double-tagged VLANs (QinQ).  This requires kernel
  74       work for reasonable performance.
  75       [optional for OF1.1+]
  76
  77     * VLANs tagged with 88a8 Ethertype.  This requires kernel work for
  78       reasonable performance.
  79       [required for OF1.1+]
  80
  81 OpenFlow 1.2
  82 ------------
  83
  84 OpenFlow 1.2 support requires OpenFlow 1.1 as a prerequisite. All the
  85 additional work specific to Openflow 1.2 are complete.  (This is based
  86 on the change log at the end of the OF1.2 spec.  I didn't compare the
  87 specs carefully yet.)
  88
  89     * Action translation needs some work to transform OpenFlow 1.1
  90       field modification actions into OpenFlow 1.2+ "set-field"
  91       actions, because OpenFlow 1.2 dropped support for the OF1.1
  92       actions.
  93
  94 OpenFlow 1.3
  95 ------------
  96
  97 OpenFlow 1.3 support requires OpenFlow 1.2 as a prerequisite, plus the
  98 following additional work.  (This is based on the change log at the
  99 end of the OF1.3 spec, reusing most of the section titles directly.  I
 100 didn't compare the specs carefully yet.)
 101
 102     * Add support for multipart requests.
 103       Currently we always report OFPBRC_MULTIPART_BUFFER_OVERFLOW.
 104       [optional for OF1.3+]
 105
 106     * Add OFPMP_TABLE_FEATURES statistics.
 107       [optional for OF1.3+]
 108
 109     * More flexible table miss support.
 110       This requires the following.
 111       - Change the default table-miss action (in the absense of table-miss
 112         entry) from packet_in to drop for OF1.3+.  Decide what to do if
 113         a switch is configured to support multiple OF versions.
 114       [required for OF1.3+]
 115
 116     * IPv6 extension header handling support.  Fully implementing this
 117       requires kernel support.  This likely will take some careful and
 118       probably time-consuming design work.  The actual coding, once
 119       that is all done, is probably 2 or 3 days work.
 120       [optional for OF1.3+]
 121
 122     * Per-flow meters.  OpenFlow protocol support is now implemented.
 123       Support for the special OFPM_SLOWPATH and OFPM_CONTROLLER meters
 124       is missing.  Support for the software switch is under review.
 125       [optional for OF1.3+]
 126
 127     * Per-connection event filtering.  OF1.3 adopted Open vSwitch's
 128       existing design for this feature so implementation should be
 129       easy.
 130       [required for OF1.3+]
 131
 132     * Auxiliary connections.  An implementation in generic code might
 133       be a week's worth of work.  The value of an implementation in
 134       generic code is questionable, though, since much of the benefit
 135       of axuiliary connections is supposed to be to take advantage of
 136       hardware support.  (We could make the kernel module somehow
 137       send packets across the auxiliary connections directly, for
 138       some kind of "hardware" support, if we judged it useful enough.)
 139       [optional for OF1.3+]
 140
 141     * MPLS BoS matching.  (Included in Simon's MPLS series?)
 142       [optional for OF1.3+]
 143
 144     * Provider Backbone Bridge tagging.  I don't plan to implement
 145       this (but we'd accept an implementation).
 146       [optional for OF1.3+]
 147
 148     * Rework tag order.  I'm not sure whether we need to do anything
 149       for this. Part of MPLS patchset by Simon Horman.
 150       [required for v1.3+]
 151
 152     * On-demand flow counters.  I think this might be a real
 153       optimization in some cases for the software switch.
 154       [optional for OF1.3+]
 155
 156 ONF OpenFlow Exensions for 1.3.X Pack1
 157 --------------------------------------
 158
 159 OpenFlow 1.3 has a bunch of ONF extentions.
 160 Many of them are necessary for OpenFlow 1.4 as well.
 161
 162     * Flow entry notifications
 163       This seems to be modelled after OVS's NXST_FLOW_MONITOR.
 164       [EXT-187]
 165       [required for OF1.4+]
 166
 167     * Role Status
 168       [EXT-191]
 169       [required for OF1.4+]
 170
 171     * Flow entry eviction
 172       OVS has flow eviction functionality.
 173       table_mod OFPTC_EVICTION, flow_mod 'importance', and
 174       table_desc ofp_table_mod_prop_eviction need to be implemented.
 175       [EXT-192-e]
 176       [optional for OF1.4+]
 177
 178     * Vacancy events
 179       [EXT-192-v]
 180       [optional for OF1.4+]
 181
 182     * Bundle
 183       Transactional modification.  OpenFlow 1.4 requires to support
 184       flow_mods and port_mods in a bundle.
 185       (Not related to OVS's 'ofbundle' stuff.)
 186       [EXT-230]
 187       [required for OF1.4+]
 188
 189     * Table synchronisation
 190       [EXT-232]
 191       [optional for OF1.4+]
 192
 193     * Group notifications
 194       [EXT-235]
 195       [optional for OF1.4+]
 196
 197     * Bad flow entry priority error
 198       Probably not so useful to the software switch.
 199       [EXT-236]
 200       [optional for OF1.4+]
 201
 202     * Set async config error
 203       [EXT-237]
 204       [optional for OF1.4+]
 205
 206     * PBB UCA header field
 207       [EXT-256]
 208       [optional for OF1.4+]
 209
 210     * Duplicate instruction error
 211       We already have ONFBIC_DUP_INSTRUCTION.
 212       [EXT-260]
 213       [required for OF1.4+]
 214
 215     * Multipart timeout error
 216       [EXT-264]
 217       [required for OF1.4+]
 218
 219 OpenFlow 1.4
 220 ------------
 221
 222     * More extensible wire protocol
 223       Many on-wire structures got TLVs.
 224       [EXT-262]
 225       [required for OF1.4+]
 226
 227     * More descriptive reasons for packet-in
 228       Distinguish OFPR_APPLY_ACTION, OFPR_ACTION_SET, OFPR_GROUP,
 229       OFPR_PACKET_OUT.  NO_MATCH was renamed to OFPR_TABLE_MISS.
 230       [EXT-136]
 231       [required for OF1.4+]
 232
 233     * Optical port properties
 234       [EXT-154]
 235       [optional for OF1.4+]
 236
 237     * Flow-removed reason for meter delete
 238       Report flow removal due to meter deletion with OFPRR_METER_DELETE.
 239       [EXT-261]
 240       [optional for OF1.4+]
 241
 242     * Meter notifications
 243       [EXT-235]
 244       [optional for OF1.4+]
 245
 246 General
 247 -----
 248
 249     * ovs-ofctl(8) often lists as Nicira extensions features that
 250       later OpenFlow versions support in standard ways.
 251
 252 How to contribute
 253 -----------------
 254
 255 If you plan to contribute code for a feature, please let everyone know
 256 on ovs-dev before you start work.  This will help avoid duplicating
 257 work.
 258
 259 Please consider the following:
 260
 261     * Testing.  Please test your code.
 262
 263     * Unit tests.  Please consider writing some.  The tests directory
 264       has many examples that you can use as a starting point.
 265
 266     * ovs-ofctl.  If you add a feature that is useful for some
 267       ovs-ofctl command then you should add support for it there.
 268
 269     * Documentation.  If you add a user-visible feature, then you
 270       should document it in the appropriate manpage and mention it in
 271       NEWS as well.
 272
 273     * Coding style (see the CodingStyle file at the top of the source
 274       tree).
 275
 276     * The patch submission guidelines (see SubmittingPatches).  I
 277       recommend using "git send-email", which automatically follows a
 278       lot of those guidelines.
 279
 280 Bug Reporting
 281 -------------
 282
 283 Please report problems to bugs@openvswitch.org.