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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. | |
58 | [required for 1.1+] | |
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. | |
65 | [required for OF1.1; optional for OF1.2+] | |
66 | ||
67 | * OFPT_TABLE_MOD message. This is new in OF1.1, so we need to | |
68 | implement it. It should be implemented so that the default OVS | |
69 | behavior does not change. | |
70 | [required for OF1.1 and OF1.2] | |
71 | ||
72 | * MPLS. Simon Horman maintains a patch series that adds this | |
73 | feature. This is partially merged. | |
74 | [optional for OF1.1+] | |
75 | ||
76 | * Match and set double-tagged VLANs (QinQ). This requires kernel | |
77 | work for reasonable performance. | |
78 | [optional for OF1.1+] | |
79 | ||
80 | * VLANs tagged with 88a8 Ethertype. This requires kernel work for | |
81 | reasonable performance. | |
82 | [required for OF1.1+] | |
83 | ||
84 | * Groups. | |
85 | ||
86 | * Type all | |
87 | [required for OF1.1+] | |
88 | ||
89 | * Type select | |
90 | [optional for OF1.1+] | |
91 | ||
92 | * Type indirect | |
93 | [required for OF1.1+] | |
94 | ||
95 | * Type fast failover | |
96 | [optional for OF1.1+] | |
97 | ||
98 | * Statistics | |
99 | [optional for OF1.1+] | |
100 | ||
101 | OpenFlow 1.2 | |
102 | ------------ | |
103 | ||
104 | OpenFlow 1.2 support requires OpenFlow 1.1 as a prerequisite. All the | |
105 | additional work specific to Openflow 1.2 are complete. (This is based | |
106 | on the change log at the end of the OF1.2 spec. I didn't compare the | |
107 | specs carefully yet.) | |
108 | ||
109 | OpenFlow 1.3 | |
110 | ------------ | |
111 | ||
112 | OpenFlow 1.3 support requires OpenFlow 1.2 as a prerequisite, plus the | |
113 | following additional work. (This is based on the change log at the | |
114 | end of the OF1.3 spec, reusing most of the section titles directly. I | |
115 | didn't compare the specs carefully yet.) | |
116 | ||
117 | * Send errors for unsupported multipart requests. | |
118 | [required for OF1.3+] | |
119 | ||
120 | * Add support for multipart requests. | |
121 | [optional for OF1.3+] | |
122 | ||
123 | * Add OFPMP_TABLE_FEATURES statistics. | |
124 | [optional for OF1.3+] | |
125 | ||
126 | * More flexible table miss support. | |
127 | [required for OF1.3+] | |
128 | ||
129 | * IPv6 extension header handling support. Fully implementing this | |
130 | requires kernel support. This likely will take some careful and | |
131 | probably time-consuming design work. The actual coding, once | |
132 | that is all done, is probably 2 or 3 days work. | |
133 | [optional for OF1.3+] | |
134 | ||
135 | * Per-flow meters. Similar to IPv6 extension headers in kernel | |
136 | and design requirements. Might be politically difficult to add | |
137 | directly to the kernel module, since its functionality overlaps | |
138 | with tc. Ideally, therefore, we could implement these somehow | |
139 | with tc, but I haven't investigated whether that makes sense. | |
140 | [optional for OF1.3+] | |
141 | ||
142 | * Per-connection event filtering. OF1.3 adopted Open vSwitch's | |
143 | existing design for this feature so implementation should be | |
144 | easy. | |
145 | [required for OF1.3+] | |
146 | ||
147 | * Auxiliary connections. An implementation in generic code might | |
148 | be a week's worth of work. The value of an implementation in | |
149 | generic code is questionable, though, since much of the benefit | |
150 | of axuiliary connections is supposed to be to take advantage of | |
151 | hardware support. (We could make the kernel module somehow | |
152 | send packets across the auxiliary connections directly, for | |
153 | some kind of "hardware" support, if we judged it useful enough.) | |
154 | [optional for OF1.3+] | |
155 | ||
156 | * MPLS BoS matching. (Included in Simon's MPLS series?) | |
157 | [optional for OF1.3+] | |
158 | ||
159 | * Provider Backbone Bridge tagging. I don't plan to implement | |
160 | this (but we'd accept an implementation). | |
161 | [optional for OF1.3+] | |
162 | ||
163 | * Rework tag order. I'm not sure whether we need to do anything | |
164 | for this. Part of MPLS patchset by Simon Horman. | |
165 | [required for v1.3+] | |
166 | ||
167 | * On-demand flow counters. I think this might be a real | |
168 | optimization in some cases for the software switch. | |
169 | [optional for OF1.3+] | |
170 | ||
171 | ||
172 | How to contribute | |
173 | ----------------- | |
174 | ||
175 | If you plan to contribute code for a feature, please let everyone know | |
176 | on ovs-dev before you start work. This will help avoid duplicating | |
177 | work. | |
178 | ||
179 | Please consider the following: | |
180 | ||
181 | * Testing. Please test your code. | |
182 | ||
183 | * Unit tests. Please consider writing some. The tests directory | |
184 | has many examples that you can use as a starting point. | |
185 | ||
186 | * ovs-ofctl. If you add a feature that is useful for some | |
187 | ovs-ofctl command then you should add support for it there. | |
188 | ||
189 | * Documentation. If you add a user-visible feature, then you | |
190 | should document it in the appropriate manpage and mention it in | |
191 | NEWS as well. | |
192 | ||
193 | * Coding style (see the CodingStyle file at the top of the source | |
194 | tree). | |
195 | ||
196 | * The patch submission guidelines (see SubmittingPatches). I | |
197 | recommend using "git send-email", which automatically follows a | |
198 | lot of those guidelines. | |
199 | ||
200 | Bug Reporting | |
201 | ------------- | |
202 | ||
203 | Please report problems to bugs@openvswitch.org. |