1 <?xml version="1.0" encoding="utf-8"?>
2 <database name="ovn-sb" title="OVN Southbound Database">
4 This database holds logical and physical configuration and state for the
5 Open Virtual Network (OVN) system to support virtual network abstraction.
6 For an introduction to OVN, please see <code>ovn-architecture</code>(7).
10 The OVN Southbound database sits at the center of the OVN
11 architecture. It is the one component that speaks both southbound
12 directly to all the hypervisors and gateways, via
13 <code>ovn-controller</code>/<code>ovn-controller-vtep</code>, and
14 northbound to the Cloud Management System, via <code>ovn-northd</code>:
17 <h2>Database Structure</h2>
20 The OVN Southbound database contains three classes of data with
21 different properties, as described in the sections below.
24 <h3>Physical Network (PN) data</h3>
27 PN tables contain information about the chassis nodes in the system. This
28 contains all the information necessary to wire the overlay, such as IP
29 addresses, supported tunnel types, and security keys.
33 The amount of PN data is small (O(n) in the number of chassis) and it
34 changes infrequently, so it can be replicated to every chassis.
38 The <ref table="Chassis"/> table comprises the PN tables.
41 <h3>Logical Network (LN) data</h3>
44 LN tables contain the topology of logical switches and routers, ACLs,
45 firewall rules, and everything needed to describe how packets traverse a
46 logical network, represented as logical datapath flows (see Logical
47 Datapath Flows, below).
51 LN data may be large (O(n) in the number of logical ports, ACL rules,
52 etc.). Thus, to improve scaling, each chassis should receive only data
53 related to logical networks in which that chassis participates. Past
54 experience shows that in the presence of large logical networks, even
55 finer-grained partitioning of data, e.g. designing logical flows so that
56 only the chassis hosting a logical port needs related flows, pays off
57 scale-wise. (This is not necessary initially but it is worth bearing in
62 The LN is a slave of the cloud management system running northbound of OVN.
63 That CMS determines the entire OVN logical configuration and therefore the
64 LN's content at any given time is a deterministic function of the CMS's
65 configuration, although that happens indirectly via the
66 <ref db="OVN_Northbound"/> database and <code>ovn-northd</code>.
70 LN data is likely to change more quickly than PN data. This is especially
71 true in a container environment where VMs are created and destroyed (and
72 therefore added to and deleted from logical switches) quickly.
76 <ref table="Logical_Flow"/> and <ref table="Multicast_Group"/> contain LN
80 <h3>Bindings data</h3>
83 Bindings data link logical and physical components. They show the current
84 placement of logical components (such as VMs and VIFs) onto chassis, and
85 map logical entities to the values that represent them in tunnel
90 Bindings change frequently, at least every time a VM powers up or down
91 or migrates, and especially quickly in a container environment. The
92 amount of data per VM (or VIF) is small.
96 Each chassis is authoritative about the VMs and VIFs that it hosts at any
97 given time and can efficiently flood that state to a central location, so
98 the consistency needs are minimal.
102 The <ref table="Port_Binding"/> and <ref table="Datapath_Binding"/> tables
103 contain binding data.
106 <h2>Common Columns</h2>
109 Some tables contain a special column named <code>external_ids</code>. This
110 column has the same form and purpose each place that it appears, so we
111 describe it here to save space later.
115 <dt><code>external_ids</code>: map of string-string pairs</dt>
117 Key-value pairs for use by the software that manages the OVN Southbound
118 database rather than by
119 <code>ovn-controller</code>/<code>ovn-controller-vtep</code>. In
120 particular, <code>ovn-northd</code> can use key-value pairs in this
121 column to relate entities in the southbound database to higher-level
122 entities (such as entities in the OVN Northbound database). Individual
123 key-value pairs in this column may be documented in some cases to aid
124 in understanding and troubleshooting, but the reader should not mistake
125 such documentation as comprehensive.
129 <table name="Chassis" title="Physical Network Hypervisor and Gateway Information">
131 Each row in this table represents a hypervisor or gateway (a chassis) in
132 the physical network (PN). Each chassis, via
133 <code>ovn-controller</code>/<code>ovn-controller-vtep</code>, adds
134 and updates its own row, and keeps a copy of the remaining rows to
135 determine how to reach other hypervisors.
139 When a chassis shuts down gracefully, it should remove its own row.
140 (This is not critical because resources hosted on the chassis are equally
141 unreachable regardless of whether the row is present.) If a chassis
142 shuts down permanently without removing its row, some kind of manual or
143 automatic cleanup is eventually needed; we can devise a process for that
148 A chassis name, taken from <ref key="system-id" table="Open_vSwitch"
149 column="external_ids" db="Open_vSwitch"/> in the Open_vSwitch
150 database's <ref table="Open_vSwitch" db="Open_vSwitch"/> table. OVN does
151 not prescribe a particular format for chassis names.
154 <group title="Encapsulation Configuration">
156 OVN uses encapsulation to transmit logical dataplane packets
160 <column name="encaps">
161 Points to supported encapsulation configurations to transmit
162 logical dataplane packets to this chassis. Each entry is a <ref
163 table="Encap"/> record that describes the configuration.
167 <group title="Gateway Configuration">
169 A <dfn>gateway</dfn> is a chassis that forwards traffic between the
170 OVN-managed part of a logical network and a physical VLAN, extending a
171 tunnel-based logical network into a physical network. Gateways are
172 typically dedicated nodes that do not host VMs and will be controlled
173 by <code>ovn-controller-vtep</code>.
176 <column name="vtep_logical_switches">
177 Stores all VTEP logical switch names connected by this gateway
178 chassis. The <ref table="Port_Binding"/> table entry with
179 <ref column="options" table="Port_Binding"/>:<code>vtep-physical-switch</code>
180 equal <ref table="Chassis"/> <ref column="name" table="Chassis"/>, and
181 <ref column="options" table="Port_Binding"/>:<code>vtep-logical-switch</code>
182 value in <ref table="Chassis"/>
183 <ref column="vtep_logical_switches" table="Chassis"/>, will be
184 associated with this <ref table="Chassis"/>.
189 <table name="Encap" title="Encapsulation Types">
191 The <ref column="encaps" table="Chassis"/> column in the <ref
192 table="Chassis"/> table refers to rows in this table to identify
193 how OVN may transmit logical dataplane packets to this chassis.
194 Each chassis, via <code>ovn-controller</code>(8) or
195 <code>ovn-controller-vtep</code>(8), adds and updates its own rows
196 and keeps a copy of the remaining rows to determine how to reach
201 The encapsulation to use to transmit packets to this chassis.
202 Hypervisors must use either <code>geneve</code> or
203 <code>stt</code>. Gateways may use <code>vxlan</code>,
204 <code>geneve</code>, or <code>stt</code>.
207 <column name="options">
208 Options for configuring the encapsulation, e.g. IPsec parameters when
209 IPsec support is introduced. No options are currently defined.
213 The IPv4 address of the encapsulation tunnel endpoint.
217 <table name="Logical_Flow" title="Logical Network Flows">
219 Each row in this table represents one logical flow.
220 <code>ovn-northd</code> populates this table with logical flows
221 that implement the L2 and L3 topologies specified in the
222 <ref db="OVN_Northbound"/> database. Each hypervisor, via
223 <code>ovn-controller</code>, translates the logical flows into
224 OpenFlow flows specific to its hypervisor and installs them into
229 Logical flows are expressed in an OVN-specific format, described here. A
230 logical datapath flow is much like an OpenFlow flow, except that the
231 flows are written in terms of logical ports and logical datapaths instead
232 of physical ports and physical datapaths. Translation between logical
233 and physical flows helps to ensure isolation between logical datapaths.
234 (The logical flow abstraction also allows the OVN centralized
235 components to do less work, since they do not have to separately
236 compute and push out physical flows to each chassis.)
240 The default action when no flow matches is to drop packets.
243 <p><em>Logical Life Cycle of a Packet</em></p>
246 This following description focuses on the life cycle of a packet through
247 a logical datapath, ignoring physical details of the implementation.
248 Please refer to <em>Life Cycle of a Packet</em> in
249 <code>ovn-architecture</code>(7) for the physical information.
253 The description here is written as if OVN itself executes these steps,
254 but in fact OVN (that is, <code>ovn-controller</code>) programs Open
255 vSwitch, via OpenFlow and OVSDB, to execute them on its behalf.
259 At a high level, OVN passes each packet through the logical datapath's
260 logical ingress pipeline, which may output the packet to one or more
261 logical port or logical multicast groups. For each such logical output
262 port, OVN passes the packet through the datapath's logical egress
263 pipeline, which may either drop the packet or deliver it to the
264 destination. Between the two pipelines, outputs to logical multicast
265 groups are expanded into logical ports, so that the egress pipeline only
266 processes a single logical output port at a time. Between the two
267 pipelines is also where, when necessary, OVN encapsulates a packet in a
268 tunnel (or tunnels) to transmit to remote hypervisors.
272 In more detail, to start, OVN searches the <ref table="Logical_Flow"/>
273 table for a row with correct <ref column="logical_datapath"/>, a <ref
274 column="pipeline"/> of <code>ingress</code>, a <ref column="table_id"/>
275 of 0, and a <ref column="match"/> that is true for the packet. If none
276 is found, OVN drops the packet. If OVN finds more than one, it chooses
277 the match with the highest <ref column="priority"/>. Then OVN executes
278 each of the actions specified in the row's <ref table="actions"/> column,
279 in the order specified. Some actions, such as those to modify packet
280 headers, require no further details. The <code>next</code> and
281 <code>output</code> actions are special.
285 The <code>next</code> action causes the above process to be repeated
286 recursively, except that OVN searches for <ref column="table_id"/> of 1
287 instead of 0. Similarly, any <code>next</code> action in a row found in
288 that table would cause a further search for a <ref column="table_id"/> of
289 2, and so on. When recursive processing completes, flow control returns
290 to the action following <code>next</code>.
294 The <code>output</code> action also introduces recursion. Its effect
295 depends on the current value of the <code>outport</code> field. Suppose
296 <code>outport</code> designates a logical port. First, OVN compares
297 <code>inport</code> to <code>outport</code>; if they are equal, it treats
298 the <code>output</code> as a no-op. In the common case, where they are
299 different, the packet enters the egress pipeline. This transition to the
300 egress pipeline discards register data, e.g. <code>reg0</code>
301 ... <code>reg5</code>, to achieve uniform behavior regardless of whether
302 the egress pipeline is on a different hypervisor (because registers
303 aren't preserve across tunnel encapsulation).
307 To execute the egress pipeline, OVN again searches the <ref
308 table="Logical_Flow"/> table for a row with correct <ref
309 column="logical_datapath"/>, a <ref column="table_id"/> of 0, a <ref
310 column="match"/> that is true for the packet, but now looking for a <ref
311 column="pipeline"/> of <code>egress</code>. If no matching row is found,
312 the output becomes a no-op. Otherwise, OVN executes the actions for the
313 matching flow (which is chosen from multiple, if necessary, as already
318 In the <code>egress</code> pipeline, the <code>next</code> action acts as
319 already described, except that it, of course, searches for
320 <code>egress</code> flows. The <code>output</code> action, however, now
321 directly outputs the packet to the output port (which is now fixed,
322 because <code>outport</code> is read-only within the egress pipeline).
326 The description earlier assumed that <code>outport</code> referred to a
327 logical port. If it instead designates a logical multicast group, then
328 the description above still applies, with the addition of fan-out from
329 the logical multicast group to each logical port in the group. For each
330 member of the group, OVN executes the logical pipeline as described, with
331 the logical output port replaced by the group member.
334 <p><em>Pipeline Stages</em></p>
337 <code>ovn-northd</code> is responsible for populating the
338 <ref table="Logical_Flow"/> table, so the stages are an
339 implementation detail and subject to change. This section
340 describes the current logical flow table.
344 The ingress pipeline consists of the following stages:
348 Port Security (Table 0): Validates the source address, drops
349 packets with a VLAN tag, and, if configured, verifies that the
350 logical port is allowed to send with the source address.
354 L2 Destination Lookup (Table 1): Forwards known unicast
355 addresses to the appropriate logical port. Unicast packets to
356 unknown hosts are forwarded to logical ports configured with the
357 special <code>unknown</code> mac address. Broadcast, and
358 multicast are flooded to all ports in the logical switch.
363 The egress pipeline consists of the following stages:
367 ACL (Table 0): Applies any specified access control lists.
371 Port Security (Table 1): If configured, verifies that the
372 logical port is allowed to receive packets with the destination
377 <column name="logical_datapath">
378 The logical datapath to which the logical flow belongs.
381 <column name="pipeline">
383 The primary flows used for deciding on a packet's destination are the
384 <code>ingress</code> flows. The <code>egress</code> flows implement
385 ACLs. See <em>Logical Life Cycle of a Packet</em>, above, for details.
389 <column name="table_id">
390 The stage in the logical pipeline, analogous to an OpenFlow table number.
393 <column name="priority">
394 The flow's priority. Flows with numerically higher priority take
395 precedence over those with lower. If two logical datapath flows with the
396 same priority both match, then the one actually applied to the packet is
400 <column name="match">
402 A matching expression. OVN provides a superset of OpenFlow matching
403 capabilities, using a syntax similar to Boolean expressions in a
404 programming language.
408 The most important components of match expression are
409 <dfn>comparisons</dfn> between <dfn>symbols</dfn> and
410 <dfn>constants</dfn>, e.g. <code>ip4.dst == 192.168.0.1</code>,
411 <code>ip.proto == 6</code>, <code>arp.op == 1</code>, <code>eth.type ==
412 0x800</code>. The logical AND operator <code>&&</code> and
413 logical OR operator <code>||</code> can combine comparisons into a
418 Matching expressions also support parentheses for grouping, the logical
419 NOT prefix operator <code>!</code>, and literals <code>0</code> and
420 <code>1</code> to express ``false'' or ``true,'' respectively. The
421 latter is useful by itself as a catch-all expression that matches every
425 <p><em>Symbols</em></p>
428 <em>Type</em>. Symbols have <dfn>integer</dfn> or <dfn>string</dfn>
429 type. Integer symbols have a <dfn>width</dfn> in bits.
433 <em>Kinds</em>. There are three kinds of symbols:
439 <dfn>Fields</dfn>. A field symbol represents a packet header or
440 metadata field. For example, a field
441 named <code>vlan.tci</code> might represent the VLAN TCI field in a
446 A field symbol can have integer or string type. Integer fields can
447 be nominal or ordinal (see <em>Level of Measurement</em>,
454 <dfn>Subfields</dfn>. A subfield represents a subset of bits from
455 a larger field. For example, a field <code>vlan.vid</code> might
456 be defined as an alias for <code>vlan.tci[0..11]</code>. Subfields
457 are provided for syntactic convenience, because it is always
458 possible to instead refer to a subset of bits from a field
463 Only ordinal fields (see <em>Level of Measurement</em>,
464 below) may have subfields. Subfields are always ordinal.
470 <dfn>Predicates</dfn>. A predicate is shorthand for a Boolean
471 expression. Predicates may be used much like 1-bit fields. For
472 example, <code>ip4</code> might expand to <code>eth.type ==
473 0x800</code>. Predicates are provided for syntactic convenience,
474 because it is always possible to instead specify the underlying
479 A predicate whose expansion refers to any nominal field or
480 predicate (see <em>Level of Measurement</em>, below) is nominal;
481 other predicates have Boolean level of measurement.
487 <em>Level of Measurement</em>. See
488 http://en.wikipedia.org/wiki/Level_of_measurement for the statistical
489 concept on which this classification is based. There are three
496 <dfn>Ordinal</dfn>. In statistics, ordinal values can be ordered
497 on a scale. OVN considers a field (or subfield) to be ordinal if
498 its bits can be examined individually. This is true for the
499 OpenFlow fields that OpenFlow or Open vSwitch makes ``maskable.''
503 Any use of a nominal field may specify a single bit or a range of
504 bits, e.g. <code>vlan.tci[13..15]</code> refers to the PCP field
505 within the VLAN TCI, and <code>eth.dst[40]</code> refers to the
506 multicast bit in the Ethernet destination address.
510 OVN supports all the usual arithmetic relations (<code>==</code>,
511 <code>!=</code>, <code><</code>, <code><=</code>,
512 <code>></code>, and <code>>=</code>) on ordinal fields and
513 their subfields, because OVN can implement these in OpenFlow and
514 Open vSwitch as collections of bitwise tests.
520 <dfn>Nominal</dfn>. In statistics, nominal values cannot be
521 usefully compared except for equality. This is true of OpenFlow
522 port numbers, Ethernet types, and IP protocols are examples: all of
523 these are just identifiers assigned arbitrarily with no deeper
524 meaning. In OpenFlow and Open vSwitch, bits in these fields
525 generally aren't individually addressable.
529 OVN only supports arithmetic tests for equality on nominal fields,
530 because OpenFlow and Open vSwitch provide no way for a flow to
531 efficiently implement other comparisons on them. (A test for
532 inequality can be sort of built out of two flows with different
533 priorities, but OVN matching expressions always generate flows with
538 String fields are always nominal.
544 <dfn>Boolean</dfn>. A nominal field that has only two values, 0
545 and 1, is somewhat exceptional, since it is easy to support both
546 equality and inequality tests on such a field: either one can be
547 implemented as a test for 0 or 1.
551 Only predicates (see above) have a Boolean level of measurement.
555 This isn't a standard level of measurement.
561 <em>Prerequisites</em>. Any symbol can have prerequisites, which are
562 additional condition implied by the use of the symbol. For example,
563 For example, <code>icmp4.type</code> symbol might have prerequisite
564 <code>icmp4</code>, which would cause an expression <code>icmp4.type ==
565 0</code> to be interpreted as <code>icmp4.type == 0 &&
566 icmp4</code>, which would in turn expand to <code>icmp4.type == 0
567 && eth.type == 0x800 && ip4.proto == 1</code> (assuming
568 <code>icmp4</code> is a predicate defined as suggested under
569 <em>Types</em> above).
572 <p><em>Relational operators</em></p>
575 All of the standard relational operators <code>==</code>,
576 <code>!=</code>, <code><</code>, <code><=</code>,
577 <code>></code>, and <code>>=</code> are supported. Nominal
578 fields support only <code>==</code> and <code>!=</code>, and only in a
579 positive sense when outer <code>!</code> are taken into account,
580 e.g. given string field <code>inport</code>, <code>inport ==
581 "eth0"</code> and <code>!(inport != "eth0")</code> are acceptable, but
582 not <code>inport != "eth0"</code>.
586 The implementation of <code>==</code> (or <code>!=</code> when it is
587 negated), is more efficient than that of the other relational
591 <p><em>Constants</em></p>
594 Integer constants may be expressed in decimal, hexadecimal prefixed by
595 <code>0x</code>, or as dotted-quad IPv4 addresses, IPv6 addresses in
596 their standard forms, or Ethernet addresses as colon-separated hex
597 digits. A constant in any of these forms may be followed by a slash
598 and a second constant (the mask) in the same form, to form a masked
599 constant. IPv4 and IPv6 masks may be given as integers, to express
604 String constants have the same syntax as quoted strings in JSON (thus,
605 they are Unicode strings).
609 Some operators support sets of constants written inside curly braces
610 <code>{</code> ... <code>}</code>. Commas between elements of a set,
611 and after the last elements, are optional. With <code>==</code>,
612 ``<code><var>field</var> == { <var>constant1</var>,
613 <var>constant2</var>,</code> ... <code>}</code>'' is syntactic sugar
614 for ``<code><var>field</var> == <var>constant1</var> ||
615 <var>field</var> == <var>constant2</var> || </code>...<code></code>.
616 Similarly, ``<code><var>field</var> != { <var>constant1</var>,
617 <var>constant2</var>, </code>...<code> }</code>'' is equivalent to
618 ``<code><var>field</var> != <var>constant1</var> &&
619 <var>field</var> != <var>constant2</var> &&
620 </code>...<code></code>''.
623 <p><em>Miscellaneous</em></p>
626 Comparisons may name the symbol or the constant first,
627 e.g. <code>tcp.src == 80</code> and <code>80 == tcp.src</code> are both
632 Tests for a range may be expressed using a syntax like <code>1024 <=
633 tcp.src <= 49151</code>, which is equivalent to <code>1024 <=
634 tcp.src && tcp.src <= 49151</code>.
638 For a one-bit field or predicate, a mention of its name is equivalent
639 to <code><var>symobl</var> == 1</code>, e.g. <code>vlan.present</code>
640 is equivalent to <code>vlan.present == 1</code>. The same is true for
641 one-bit subfields, e.g. <code>vlan.tci[12]</code>. There is no
642 technical limitation to implementing the same for ordinal fields of all
643 widths, but the implementation is expensive enough that the syntax
644 parser requires writing an explicit comparison against zero to make
645 mistakes less likely, e.g. in <code>tcp.src != 0</code> the comparison
646 against 0 is required.
650 <em>Operator precedence</em> is as shown below, from highest to lowest.
651 There are two exceptions where parentheses are required even though the
652 table would suggest that they are not: <code>&&</code> and
653 <code>||</code> require parentheses when used together, and
654 <code>!</code> requires parentheses when applied to a relational
655 expression. Thus, in <code>(eth.type == 0x800 || eth.type == 0x86dd)
656 && ip.proto == 6</code> or <code>!(arp.op == 1)</code>, the
657 parentheses are mandatory.
661 <li><code>()</code></li>
662 <li><code>== != < <= > >=</code></li>
663 <li><code>!</code></li>
664 <li><code>&& ||</code></li>
668 <em>Comments</em> may be introduced by <code>//</code>, which extends
669 to the next new-line. Comments within a line may be bracketed by
670 <code>/*</code> and <code>*/</code>. Multiline comments are not
674 <p><em>Symbols</em></p>
677 Most of the symbols below have integer type. Only <code>inport</code>
678 and <code>outport</code> have string type. <code>inport</code> names a
679 logical port. Thus, its value is a <ref column="logical_port"/> name
680 from the <ref table="Port_Binding"/> table. <code>outport</code> may
681 name a logical port, as <code>inport</code>, or a logical multicast
682 group defined in the <ref table="Multicast_Group"/> table. For both
683 symbols, only names within the flow's logical datapath may be used.
687 <li><code>reg0</code>...<code>reg5</code></li>
688 <li><code>inport</code> <code>outport</code></li>
689 <li><code>eth.src</code> <code>eth.dst</code> <code>eth.type</code></li>
690 <li><code>vlan.tci</code> <code>vlan.vid</code> <code>vlan.pcp</code> <code>vlan.present</code></li>
691 <li><code>ip.proto</code> <code>ip.dscp</code> <code>ip.ecn</code> <code>ip.ttl</code> <code>ip.frag</code></li>
692 <li><code>ip4.src</code> <code>ip4.dst</code></li>
693 <li><code>ip6.src</code> <code>ip6.dst</code> <code>ip6.label</code></li>
694 <li><code>arp.op</code> <code>arp.spa</code> <code>arp.tpa</code> <code>arp.sha</code> <code>arp.tha</code></li>
695 <li><code>tcp.src</code> <code>tcp.dst</code> <code>tcp.flags</code></li>
696 <li><code>udp.src</code> <code>udp.dst</code></li>
697 <li><code>sctp.src</code> <code>sctp.dst</code></li>
698 <li><code>icmp4.type</code> <code>icmp4.code</code></li>
699 <li><code>icmp6.type</code> <code>icmp6.code</code></li>
700 <li><code>nd.target</code> <code>nd.sll</code> <code>nd.tll</code></li>
704 The following predicates are supported:
708 <li><code>vlan.present</code> expands to <code>vlan.tci[12]</code></li>
709 <li><code>ip4</code> expands to <code>eth.type == 0x800</code></li>
710 <li><code>ip6</code> expands to <code>eth.type == 0x86dd</code></li>
711 <li><code>ip</code> expands to <code>ip4 || ip6</code></li>
712 <li><code>icmp4</code> expands to <code>ip4 && ip.proto == 1</code></li>
713 <li><code>icmp6</code> expands to <code>ip6 && ip.proto == 58</code></li>
714 <li><code>icmp</code> expands to <code>icmp4 || icmp6</code></li>
715 <li><code>ip.is_frag</code> expands to <code>ip.frag[0]</code></li>
716 <li><code>ip.later_frag</code> expands to <code>ip.frag[1]</code></li>
717 <li><code>ip.first_frag</code> expands to <code>ip.is_frag && !ip.later_frag</code></li>
718 <li><code>arp</code> expands to <code>eth.type == 0x806</code></li>
719 <li><code>nd</code> expands to <code>icmp6.type == {135, 136} && icmp6.code == 0</code></li>
720 <li><code>tcp</code> expands to <code>ip.proto == 6</code></li>
721 <li><code>udp</code> expands to <code>ip.proto == 17</code></li>
722 <li><code>sctp</code> expands to <code>ip.proto == 132</code></li>
726 <column name="actions">
728 Logical datapath actions, to be executed when the logical flow
729 represented by this row is the highest-priority match.
733 Actions share lexical syntax with the <ref column="match"/> column. An
734 empty set of actions (or one that contains just white space or
735 comments), or a set of actions that consists of just
736 <code>drop;</code>, causes the matched packets to be dropped.
737 Otherwise, the column should contain a sequence of actions, each
738 terminated by a semicolon.
742 The following actions are defined:
746 <dt><code>output;</code></dt>
749 In the ingress pipeline, this action executes the
750 <code>egress</code> pipeline as a subroutine. If
751 <code>outport</code> names a logical port, the egress pipeline
752 executes once; if it is a multicast group, the egress pipeline runs
753 once for each logical port in the group.
757 In the egress pipeline, this action performs the actual
758 output to the <code>outport</code> logical port. (In the egress
759 pipeline, <code>outport</code> never names a multicast group.)
763 Output to the input port is implicitly dropped, that is,
764 <code>output</code> becomes a no-op if <code>outport</code> ==
769 <dt><code>next;</code></dt>
771 Executes the next logical datapath table as a subroutine.
774 <dt><code><var>field</var> = <var>constant</var>;</code></dt>
777 Sets data or metadata field <var>field</var> to constant value
778 <var>constant</var>, e.g. <code>outport = "vif0";</code> to set the
779 logical output port. To set only a subset of bits in a field,
780 specify a subfield for <var>field</var> or a masked
781 <var>constant</var>, e.g. one may use <code>vlan.pcp[2] = 1;</code>
782 or <code>vlan.pcp = 4/4;</code> to set the most sigificant bit of
787 Assigning to a field with prerequisites implicitly adds those
788 prerequisites to <ref column="match"/>; thus, for example, a flow
789 that sets <code>tcp.dst</code> applies only to TCP flows,
790 regardless of whether its <ref column="match"/> mentions any TCP
795 Not all fields are modifiable (e.g. <code>eth.type</code> and
796 <code>ip.proto</code> are read-only), and not all modifiable fields
797 may be partially modified (e.g. <code>ip.ttl</code> must assigned
798 as a whole). The <code>outport</code> field is modifiable in the
799 <code>ingress</code> pipeline but not in the <code>egress</code>
806 The following actions will likely be useful later, but they have not
807 been thought out carefully.
811 <dt><code><var>field1</var> = <var>field2</var>;</code></dt>
813 Extends the assignment action to allow copying between fields.
816 <dt><code>learn</code></dt>
818 <dt><code>conntrack</code></dt>
820 <dt><code>dec_ttl { <var>action</var>, </code>...<code> } { <var>action</var>; </code>...<code>};</code></dt>
822 decrement TTL; execute first set of actions if
823 successful, second set if TTL decrement fails
826 <dt><code>icmp_reply { <var>action</var>, </code>...<code> };</code></dt>
827 <dd>generate ICMP reply from packet, execute <var>action</var>s</dd>
829 <dt><code>arp { <var>action</var>, </code>...<code> }</code></dt>
830 <dd>generate ARP from packet, execute <var>action</var>s</dd>
834 <column name="external_ids" key="stage-name">
835 Human-readable name for this flow's stage in the pipeline.
838 <group title="Common Columns">
839 The overall purpose of these columns is described under <code>Common
840 Columns</code> at the beginning of this document.
842 <column name="external_ids"/>
846 <table name="Multicast_Group" title="Logical Port Multicast Groups">
848 The rows in this table define multicast groups of logical ports.
849 Multicast groups allow a single packet transmitted over a tunnel to a
850 hypervisor to be delivered to multiple VMs on that hypervisor, which
851 uses bandwidth more efficiently.
855 Each row in this table defines a logical multicast group numbered <ref
856 column="tunnel_key"/> within <ref column="datapath"/>, whose logical
857 ports are listed in the <ref column="ports"/> column.
860 <column name="datapath">
861 The logical datapath in which the multicast group resides.
864 <column name="tunnel_key">
865 The value used to designate this logical egress port in tunnel
866 encapsulations. An index forces the key to be unique within the <ref
867 column="datapath"/>. The unusual range ensures that multicast group IDs
868 do not overlap with logical port IDs.
873 The logical multicast group's name. An index forces the name to be
874 unique within the <ref column="datapath"/>. Logical flows in the
875 ingress pipeline may output to the group just as for individual logical
876 ports, by assigning the group's name to <code>outport</code> and
877 executing an <code>output</code> action.
881 Multicast group names and logical port names share a single namespace
882 and thus should not overlap (but the database schema cannot enforce
883 this). To try to avoid conflicts, <code>ovn-northd</code> uses names
884 that begin with <code>_MC_</code>.
888 <column name="ports">
889 The logical ports included in the multicast group. All of these ports
890 must be in the <ref column="datapath"/> logical datapath (but the
891 database schema cannot enforce this).
895 <table name="Datapath_Binding" title="Physical-Logical Datapath Bindings">
897 Each row in this table identifies physical bindings of a logical
898 datapath. A logical datapath implements a logical pipeline among the
899 ports in the <ref table="Port_Binding"/> table associated with it. In
900 practice, the pipeline in a given logical datapath implements either a
901 logical switch or a logical router.
904 <column name="tunnel_key">
905 The tunnel key value to which the logical datapath is bound.
906 The <code>Tunnel Encapsulation</code> section in
907 <code>ovn-architecture</code>(7) describes how tunnel keys are
908 constructed for each supported encapsulation.
911 <column name="external_ids" key="logical-switch" type='{"type": "uuid"}'>
912 Each row in <ref table="Datapath_Binding"/> is associated with some
913 logical datapath. <code>ovn-northd</code> uses this key to store the
914 UUID of the logical datapath <ref table="Logical_Switch"
915 db="OVN_Northbound"/> row in the <ref db="OVN_Northbound"/> database.
918 <group title="Common Columns">
919 The overall purpose of these columns is described under <code>Common
920 Columns</code> at the beginning of this document.
922 <column name="external_ids"/>
926 <table name="Port_Binding" title="Physical-Logical Port Bindings">
928 Each row in this table identifies the physical location of a logical
933 For every <code>Logical_Port</code> record in <code>OVN_Northbound</code>
934 database, <code>ovn-northd</code> creates a record in this table.
935 <code>ovn-northd</code> populates and maintains every column except
936 the <code>chassis</code> column, which it leaves empty in new records.
940 <code>ovn-controller</code>/<code>ovn-controller-vtep</code>
941 populates the <code>chassis</code> column for the records that
942 identify the logical ports that are located on its hypervisor/gateway,
943 which <code>ovn-controller</code>/<code>ovn-controller-vtep</code> in
944 turn finds out by monitoring the local hypervisor's Open_vSwitch
945 database, which identifies logical ports via the conventions described
946 in <code>IntegrationGuide.md</code>.
950 When a chassis shuts down gracefully, it should clean up the
951 <code>chassis</code> column that it previously had populated.
952 (This is not critical because resources hosted on the chassis are equally
953 unreachable regardless of whether their rows are present.) To handle the
954 case where a VM is shut down abruptly on one chassis, then brought up
955 again on a different one,
956 <code>ovn-controller</code>/<code>ovn-controller-vtep</code> must
957 overwrite the <code>chassis</code> column with new information.
960 <column name="datapath">
961 The logical datapath to which the logical port belongs.
964 <column name="logical_port">
965 A logical port, taken from <ref table="Logical_Port" column="name"
966 db="OVN_Northbound"/> in the OVN_Northbound database's
967 <ref table="Logical_Port" db="OVN_Northbound"/> table. OVN does not
968 prescribe a particular format for the logical port ID.
973 A type for this logical port. Logical ports can be used to model
974 other types of connectivity into an OVN logical switch. Leaving this
975 column blank maintains the default logical port behavior, which
976 is for a VM (or VIF) interface. The following other types are defined:
980 <dt><code>localnet</code></dt>
981 <dd>A connection to a locally accessible network from each
982 <code>ovn-controller</code> instance. A logical switch can only
983 have a single <code>localnet</code> port attached and at most one
984 regular logical port. This is used to model direct connectivity
985 to an existing network.</dd>
989 <dt><code>vtep</code></dt>
990 <dd>A port to a logical switch on a VTEP gateway chassis. In order
991 to get this port correctly recognized by the OVN controller, the
992 <ref column="options" table="Port_Binding"/>:<code>vtep-physical-switch</code>
993 and <ref column="options" table="Port_Binding"/>:<code>vtep-logical-switch</code>
994 must also be defined.</dd>
998 <column name="options">
1000 This column provides key/value settings specific to the logical port
1001 <ref column="type"/>. The following options are defined:
1005 <dt><code>network_name</code></dt>
1007 Must be set when <ref column="type"/> is <code>localnet</code>.
1008 <code>ovn-controller</code> uses the configuration entry
1009 <code>ovn-bridge-mappings</code> to determine how to connect to
1010 this network. <code>ovn-bridge-mappings</code> is a list of
1011 network names mapped to a local OVS bridge that provides access
1012 to that network. An example of configuring
1013 <code>ovn-bridge-mappings</code> would be:
1016 <code>$ ovs-vsctl set open
1017 . external-ids:ovn-bridge-mappings=physnet1:br-eth0,physnet2:br-eth1</code>
1021 Also note that when a logical switch has a <code>localnet</code>
1022 port attached, every chassis that may have a local vif attached
1023 to that logical switch must have a bridge mapping configured to
1024 reach that <code>localnet</code>. Traffic that arrives on a
1025 <code>localnet</code> port is never forwarded over a tunnel to
1032 <dt><code>vtep-physical-switch</code></dt>
1034 The name of the VTEP gateway. Must be set when
1035 <ref column="type"/> is <code>vtep</code>.
1040 <dt><code>vtep-logical-switch</code></dt>
1042 A logical switch name connected by the VTEP gateway. Must be
1043 set when <ref column="type"/> is <code>vtep</code>.
1048 <column name="tunnel_key">
1050 A number that represents the logical port in the key (e.g. STT key or
1051 Geneve TLV) field carried within tunnel protocol packets.
1055 The tunnel ID must be unique within the scope of a logical datapath.
1059 <column name="parent_port">
1060 For containers created inside a VM, this is taken from
1061 <ref table="Logical_Port" column="parent_name" db="OVN_Northbound"/>
1062 in the OVN_Northbound database's <ref table="Logical_Port"
1063 db="OVN_Northbound"/> table. It is left empty if
1064 <ref column="logical_port"/> belongs to a VM or a container created
1069 When <ref column="logical_port"/> identifies the interface of a container
1070 spawned inside a VM, this column identifies the VLAN tag in
1071 the network traffic associated with that container's network interface.
1072 It is left empty if <ref column="logical_port"/> belongs to a VM or a
1073 container created in the hypervisor.
1076 <column name="chassis">
1077 The physical location of the logical port. To successfully identify a
1078 chassis, this column must be a <ref table="Chassis"/> record. This is
1079 populated by <code>ovn-controller</code>/<code>ovn-controller-vtep</code>.
1084 The Ethernet address or addresses used as a source address on the
1085 logical port, each in the form
1086 <var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>:<var>xx</var>.
1087 The string <code>unknown</code> is also allowed to indicate that the
1088 logical port has an unknown set of (additional) source addresses.
1092 A VM interface would ordinarily have a single Ethernet address. A
1093 gateway port might initially only have <code>unknown</code>, and then
1094 add MAC addresses to the set as it learns new source addresses.