---
Documentation/automake.mk | 4 +-
Documentation/conf.py | 2 +
Documentation/ref/index.rst | 1 +
Documentation/ref/ovs-flowviz.8.rst | 531 ++++++++++++++++++++
Documentation/topics/flow-visualization.rst | 271 ++++++++++
Documentation/topics/index.rst | 1 +
6 files changed, 809 insertions(+), 1 deletion(-)
create mode 100644 Documentation/ref/ovs-flowviz.8.rst
create mode 100644 Documentation/topics/flow-visualization.rst
diff --git a/Documentation/automake.mk b/Documentation/automake.mk
index 47d2e336a..539870aa2 100644
--- a/Documentation/automake.mk
+++ b/Documentation/automake.mk
@@ -45,7 +45,7 @@ DOC_SOURCE = \
Documentation/topics/fuzzing/ovs-fuzzing-infrastructure.rst \
Documentation/topics/fuzzing/ovs-fuzzers.rst \
Documentation/topics/fuzzing/security-analysis-of-ovs-fuzzers.rst \
- Documentation/topics/testing.rst \
+ Documentation/topics/flow-visualization.rst \
Documentation/topics/integration.rst \
Documentation/topics/language-bindings.rst \
Documentation/topics/networking-namespaces.rst \
@@ -55,6 +55,7 @@ DOC_SOURCE = \
Documentation/topics/ovsdb-replication.rst \
Documentation/topics/porting.rst \
Documentation/topics/record-replay.rst \
+ Documentation/topics/testing.rst \
Documentation/topics/tracing.rst \
Documentation/topics/usdt-probes.rst \
Documentation/topics/userspace-checksum-offloading.rst \
@@ -162,6 +163,7 @@ RST_MANPAGES = \
ovs-actions.7.rst \
ovs-appctl.8.rst \
ovs-ctl.8.rst \
+ ovs-flowviz.8.rst \
ovs-l3ping.8.rst \
ovs-parse-backtrace.8.rst \
ovs-pki.8.rst \
diff --git a/Documentation/conf.py b/Documentation/conf.py
index 15785605a..3a82f23a7 100644
--- a/Documentation/conf.py
+++ b/Documentation/conf.py
@@ -120,6 +120,8 @@ _man_pages = [
u'utility for configuring running Open vSwitch daemons'),
('ovs-ctl.8',
u'OVS startup helper script'),
+ ('ovs-flowviz.8',
+ u'utility for visualizing OpenFlow and datapath flows'),
('ovs-l3ping.8',
u'check network deployment for L3 tunneling problems'),
('ovs-parse-backtrace.8',
diff --git a/Documentation/ref/index.rst b/Documentation/ref/index.rst
index 03ada932f..7f2fe6177 100644
--- a/Documentation/ref/index.rst
+++ b/Documentation/ref/index.rst
@@ -42,6 +42,7 @@ time:
ovs-actions.7
ovs-appctl.8
ovs-ctl.8
+ ovs-flowviz.8
ovs-l3ping.8
ovs-pki.8
ovs-sim.1
diff --git a/Documentation/ref/ovs-flowviz.8.rst
b/Documentation/ref/ovs-flowviz.8.rst
new file mode 100644
index 000000000..b5b1befb0
--- /dev/null
+++ b/Documentation/ref/ovs-flowviz.8.rst
@@ -0,0 +1,531 @@
+..
+ Licensed under the Apache License, Version 2.0 (the "License"); you may
+ not use this file except in compliance with the License. You may obtain
+ a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ License for the specific language governing permissions and limitations
+ under the License.
+
+ Convention for heading levels in Open vSwitch documentation:
+
+ ======= Heading 0 (reserved for the title in a document)
+ ------- Heading 1
+ ~~~~~~~ Heading 2
+ +++++++ Heading 3
+ ''''''' Heading 4
+
+ Avoid deeper levels because they do not render well.
+
+===========
+ovs-flowviz
+===========
+
+Synopsis
+========
+
+``ovs-flowviz``
+[``[-i | --input] <[alias,]file>``]
+[``[-c | --config] <file>``]
+[``[-f | --filter] <filter>``]
+[``[-h | --highlight] <filter>``]
+[``--style <style>``]
+*<flow_type>* *<format>* [<arg>...]
+
+``ovs-flowviz --help``
+
+Description
+===========
+
+The ``ovs-flowviz`` program helps visualize OpenFlow and datapath flow dumps
+in different formats in order to make them more easily understood.
+
+The program works by reading flows from ``stdin`` or from a file specified
+in the ``--input`` option, filtering them, highlighting them, and finally
+outputting them in one of the predefined formats.
+
+
+Options
+=======
+
+.. program: ovs-flowviz
+
+.. option:: -h, --help
+
+ Prints a brief help message to the console.
+
+.. option:: -i <[alias,]file>, --input <[alias,]file>
+
+ Specifies the file to read flows from. If not provided, ``ovs-flowviz``
+ will read flows from stdin.
+
+ This option can be specified multiple times.
+ The file path can prepended by an alias that will be shown in the output.
+ For example: ``--input node1,/path/to/file1 --input node2,/path/to/file2``
+
+.. option:: -c <file>, --config <file>
+
+ Specifies the style configuration file to use. ``ovs-flowviz`` ships with
+ a default configuration file but it can be overridden using this option.
+ Styles defined in the style configuration file will be select-able using
+ the ``--style`` option.
+
+ For more details on the style configuration file, see
+ `Style Configuration File`_ section below.
+
+.. option:: -f <filter>, --filter <filter>
+
+ Tells ``ovs-flowviz`` to filter the flows and only show the ones that match
+ the expression (although some formats implement filtering differently,
+ see `Datapath tree format`_ below).
+
+ The filtering syntax is detailed in `Filtering Syntax`_.
+
+.. option:: -h <filter>, --highlight <filter>
+
+ Tells ``ovs-flowviz`` to highlight the flows that match the provided filter
+
+ The filtering syntax is detailed in `Filtering Syntax`_.
+
+.. option:: --style <style>
+
+ Specifies the style to use. The style must have been defined in the
+ style configuration file.
+
+.. option:: <flow_type>
+
+ "openflow" or "datapath".
+
+.. option:: <format>
+
+ See `Supported formats`_ section.
+
+
+Supported formats
+=================
+
+``ovs-flowviz`` supports several visualization formats for both OpenFlow and
+datapath flows that are summarized in the following table:
+
+.. list-table::
+ :widths: 20 10 70
+ :align: center
+ :header-rows: 1
+
+ * - Flow Type
+ - Format
+ - Description
+ * - Both
+ - console
+ - Prints the flows in a configurable, colorful style in the console.
+ * - Both
+ - json
+ - Prints the flows in JSON format.
+ * - Both
+ - html
+ - Prints the flows in an HTML list.
+ * - Openflow
+ - cookie
+ - Prints the flows in the console sorted by cookie.
+ * - Openflow
+ - logic
+ - Prints the logical structure of flows in the console.
+ * - Datapath
+ - tree
+ - Prints the flows a tree structure arranged by `recirc_id`.
+ * - Datapath
+ - graph
+ - Prints a graphviz graph of the flows arranged by `recirc_id`.
+
+
+Console format
+~~~~~~~~~~~~~~
+
+The ``console`` works for both OpenFlow and datapath flow types and prints
+flows in the terminal with the style determined by the ``--style`` option.
+
+Additionally, it accepts the following arguments:
+
+.. option:: -h, --heat-map
+
+ This option changes the color of the packet and byte counters to reflect
+ their relative size. The color gradient goes through the following colors:
+ blue (coldest, lowest), cyan, green, yellow, red (hottest, highest)
+
+ Note filtering is applied before the range is calculated.
+
+
+JSON format
+~~~~~~~~~~~
+
+The ``json`` format works for both OpenFlow and datapath flow types and prints
+flows in JSON format. See `JSON Syntax`_ for more details.
+
+
+HTML format
+~~~~~~~~~~~
+
+The ``html`` format works for both OpenFlow and datapath flows and prints
+flows in an HTML table that offers some basic interactivity. OpenFlow flows
+are sorted in tables and datapath flows are arranged in flow trees
+(see `Datapath tree format`_ for more details).
+
+Styles defined via Style Configuration File and selected via ``--style`` option
+also apply to ``html`` format.
+
+
+OpenFlow cookie format
+~~~~~~~~~~~~~~~~~~~~~~
+
+The OpenFlow ``cookie`` format is similar to the ``console`` format but
+instead of arranging the flows per table, it arranges the flows per cookie.
+
+
+Openflow logic format
+~~~~~~~~~~~~~~~~~~~~~
+
+The OpenFlow ``logic`` format helps visualize the logic structure of OpenFlow
+pipelines by arranging flows into *logical blocks*.
+A logical block is a set of flows that have:
+
+* Same ``priority``.
+* Match on the same fields (regardless of the match value and mask).
+* Execute the same actions (regardless of the actions' arguments,
+ except for resubmit and output).
+* Optionally, the ``cookie`` can be counted as part of the logical flow.
+
+This format supports the following extra arguments:
+
+.. option:: -s, --show-flows
+
+ Show all the flows under each logical block.
+
+.. option:: -d, --ovn-detrace
+
+ Use ovn-detrace.py script to extract cookie information (implies '-c').
+
+.. option:: -c, --cookie
+
+ Consider the cookie in the logical block.
+
+.. option:: --ovn-detrace-path <path>
+
+ Use an alternative path to look for ovn_detrace.py script.
+
+.. option:: --ovnnb-db text
+
+ Specify the OVN NB database string (implies '-d').
+ Default value is "unix:/var/run/ovn/ovnnb_db.sock".
+
+.. option:: --ovnsb-db text
+
+ Specify the OVN SB database string (implies '-d').
+ Default value is "unix:/var/run/ovn/ovnsb_db.sock".
+
+.. option:: --o <text>, --ovn-filter <text>
+
+ Specify the a filter to be run on the ovn-detrace information.
+ Syntax: python regular expression
+ (See https://docs.python.org/3/library/re.html).
+
+.. option:: -h, --heat-map
+
+ This option changes the color of the packet and byte counters to reflect
+ their relative size. The color gradient goes through the following colors:
+ blue (coldest, lowest), cyan, green, yellow, red (hottest, highest)
+
+ Note filtering is applied before the range is calculated.
+
+
+Datapath tree format
+~~~~~~~~~~~~~~~~~~~~
+
+The datapath ``tree`` format arranges datapath flows in a hierarchical tree
+based on `recirc_id`. At the first level, flows with `recirc_id(0)` are
+listed. If a flow contains a `recirc()` action with a specific `recirc_id`,
+flows matching on that `recirc_id` are listed below. This is done recursively
+for all actions.
+
+The result is a hierarchical representation that helps understand how actions
+are related to each other via recirculation. Note flows with a specific
+non-zero `recirc_id` are listed below each flow that has a corresponding
+`recirc()` action. Therefore, they would be duplicated leading to a longer
+output.
+
+Also, filtering works in a slightly different way for datapath flow trees.
+Unlike other formats where a filter simply removes non-matching flows,
+the output of a filtered datapath flow tree will show full sub-trees
+that contain at least one flow that satisfies the filter.
+
+The ``html`` format prints this same tree in an interactive HTML table.
+
+
+Datapath graph format
+~~~~~~~~~~~~~~~~~~~~~
+
+The datapath ``graph`` generates a graphviz visual representation of the
+same tree-like flow hierarchy that the ``tree`` format prints.
+
+It supports the following extra argument:
+
+.. option:: -h, --html
+
+ Prints the graphviz format in an svg image alongside the interactive HTML
+ table of flows (that 'html' format would print).
+
+
+JSON Syntax
+===========
+
+Both OpenFlow and datapath `json` formats print a JSON list of JSON
+objects each of one representing an individual flow.S
+
+
+Filtering syntax
+================
+
+``ovs-flowviz`` provides rich highlighting and filtering. The special command
+``ovs-flowviz filter`` dumps the filtering syntax:
+
+::
+
+ $ ovs-flowviz filter
+ Filter Syntax
+ *************
+
+ [! | not ] {key}[[.subkey]...] [OPERATOR] {value})] [LOGICAL OPERATOR]
...
+
+ Comparison operators are:
+ = equality
+ < less than
+ > more than
+ ~= masking (valid for IP and Ethernet fields)
+
+ Logical operators are:
+ !{expr}: NOT
+ {expr} && {expr}: AND
+ {expr} || {expr}: OR
+
+ Matches and flow metadata:
+ To compare against a match or info field, use the field directly,
e.g:
+ priority=100
+ n_bytes>10
+ Use simple keywords for flags:
+ tcp and ip_src=192.168.1.1
+
+ Actions:
+ Actions values might be dictionaries, use subkeys to access
individual
+ values, e.g:
+ output.port=3
+ Use simple keywords for flags
+ drop
+
+ Examples of valid filters.
+ nw_addr~=192.168.1.1 && (tcp_dst=80 || tcp_dst=443)
+ arp=true && !arp_tsa=192.168.1.1
+ n_bytes>0 && drop=true
+
+
+Example expressions:
+::
+
+ n_bytes > 0 and drop
+ nw_src~=192.168.1.1 or arp.tsa=192.168.1.1
+ ! tcp && output.port=2
+
+
+Examples
+========
+
+Print OpenFlow flows sorted by cookie adding OVN data to each one:
+::
+
+ $ ovs-flowviz -i flows.txt openflow cookie --ovn-detrace
+
+Print OpenFlow logical structure, showing the flows and heat-map:
+::
+
+ $ ovs-flowviz -i flows.txt openflow logic --show-flows --heat-map
+
+Display OpenFlow flows in HTML format with "light" style and highlight drops:
+::
+
+ $ ovs-flowviz -i flows.txt --style "light" --highlight "n_packets > 0 and
drop" openflow html > flows.html
+
+Display the datapath flows in an interactive graphviz + HTML view:
+::
+
+ $ ovs-flowviz -i flows.txt datapath graph --html > flows.html
+
+Display the datapath flow trees that lead to packets being sent to port 10:
+::
+
+ $ ovs-flowviz -i flows.txt --filter "output.port=10" datapath tree
diff --git a/Documentation/topics/flow-visualization.rst
b/Documentation/topics/flow-visualization.rst
new file mode 100644
index 000000000..62d0d6bd8
--- /dev/null
+++ b/Documentation/topics/flow-visualization.rst
@@ -0,0 +1,271 @@
+..
+ Licensed under the Apache License, Version 2.0 (the "License"); you may
+ not use this file except in compliance with the License. You may obtain
+ a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ License for the specific language governing permissions and limitations
+ under the License.
+
+ Convention for heading levels in Open vSwitch documentation:
+
+ ======= Heading 0 (reserved for the title in a document)
+ ------- Heading 1
+ ~~~~~~~ Heading 2
+ +++++++ Heading 3
+ ''''''' Heading 4
+
+ Avoid deeper levels because they do not render well.
+
+==================================
+Visualizing flows with ovs-flowviz
+==================================
+
+When troubleshooting networking issues with OVS, we typically end up looking
+at OpenFlow or datapath flow dumps. These dumps tend to be quite dense and
+difficult to reason about.
+
+``ovs-flowviz`` is a utility script that helps visualizing OpenFlow and
+datapath flows to make it easier to understand what is going on.
+
+The `ovs-flowviz(8)`_ manpage describes its basic usage. In this document a few
+of its advanced visualization formats will be expanded.
+
+
+Installing ovs-flowviz
+----------------------
+
+``ovs-flowviz`` is part of the openvswitch python package but its
+extra dependencies have to be installed explicitly by running:
+::
+
+ $ pip install openvswitch[flowviz]
+
+Or, if you are working with the OVS tree:
+::
+
+ $ cd python && pip install .[flowviz]
+
+Visualizing OpenFlow logical block
+----------------------------------
+
+When controllers such as OVN write OpenFlow flows, they typically organize
+flows in functional blocks. These blocks can expand to multiple flows that
+"look similar", in the sense that they match on the same fields and have
+similar actions.
+
+However, when we look at a flow dump the number of flows can make it difficult
+to perceive this logical functionality that the controller is trying to
+implement using OpenFlow.
+
+In this example, we are going to use ``ovs-flowviz openflow logic``
+visualization to understand an OVN flow dump a bit better.
+
+On a particular flow dump we have 23 flows in table 0:
+::
+
+ $ grep -c "table=0" flows.txt
+ 23
+
+If we look at the first few lines, the amount of information can be
+overwhelming and difficult our analysis:
+
+::
+
+ $ head flows.txt
+ cookie=0xf76b4b20, duration=765.107s, table=0, n_packets=0, n_bytes=0,
priority=180,vlan_tci=0x0000/0x1000 actions=conjunction(100,2/2)
+ cookie=0xf76b4b20, duration=765.107s, table=0, n_packets=0, n_bytes=0,
priority=180,conj_id=100,in_port="patch-br-int-to",vlan_tci=0x0000/0x1000
actions=load:0xa->NXM_NX_REG13[],load:0xc->NXM_NX_REG11[],load:0xb->NXM_NX_REG12[],load:0xb->OXM_OF_METADATA[],load:0x1->NXM_NX_REG14[],mod_dl_src:02:42:ac:12:00:03,resubmit(,8)
+ cookie=0x0, duration=765.388s, table=0, n_packets=0, n_bytes=0,
priority=100,in_port="ovn-6bb3b3-0"
actions=move:NXM_NX_TUN_ID[0..23]->OXM_OF_METADATA[0..23],move:NXM_NX_TUN_METADATA0[16..30]->NXM_NX_REG14[0..14],move:NXM_NX_TUN_METADATA0[0..15]->NXM_NX_REG15[0..15],resubmit(,40)
+ cookie=0x0, duration=765.388s, table=0, n_packets=0, n_bytes=0,
priority=100,in_port="ovn-a6ff98-0"
actions=move:NXM_NX_TUN_ID[0..23]->OXM_OF_METADATA[0..23],move:NXM_NX_TUN_METADATA0[16..30]->NXM_NX_REG14[0..14],move:NXM_NX_TUN_METADATA0[0..15]->NXM_NX_REG15[0..15],resubmit(,40)
+ cookie=0xf2ca6195, duration=765.107s, table=0, n_packets=6, n_bytes=636,
priority=100,in_port="ovn-k8s-mp0"
actions=load:0x1->NXM_NX_REG13[],load:0x2->NXM_NX_REG11[],load:0x7->NXM_NX_REG12[],load:0x4->OXM_OF_METADATA[],load:0x2->NXM_NX_REG14[],resubmit(,8)
+ cookie=0x236e941d, duration=408.874s, table=0, n_packets=11, n_bytes=846,
priority=100,in_port=aceac9829941d11
actions=load:0x11->NXM_NX_REG13[],load:0x2->NXM_NX_REG11[],load:0x7->NXM_NX_REG12[],load:0x4->OXM_OF_METADATA[],load:0x3->NXM_NX_REG14[],resubmit(,8)
+ cookie=0x3facf689, duration=405.581s, table=0, n_packets=11, n_bytes=846,
priority=100,in_port="363ba22029cd92b"
actions=load:0x12->NXM_NX_REG13[],load:0x2->NXM_NX_REG11[],load:0x7->NXM_NX_REG12[],load:0x4->OXM_OF_METADATA[],load:0x4->NXM_NX_REG14[],resubmit(,8)
+ cookie=0xe7c8c4bb, duration=405.570s, table=0, n_packets=11, n_bytes=846,
priority=100,in_port="6a62cde0d50ef44"
actions=load:0x13->NXM_NX_REG13[],load:0x2->NXM_NX_REG11[],load:0x7->NXM_NX_REG12[],load:0x4->OXM_OF_METADATA[],load:0x5->NXM_NX_REG14[],resubmit(,8)
+ cookie=0x99a0ffc1, duration=59.391s, table=0, n_packets=8, n_bytes=636,
priority=100,in_port="5ff3bfaaa4eb622"
actions=load:0x14->NXM_NX_REG13[],load:0x2->NXM_NX_REG11[],load:0x7->NXM_NX_REG12[],load:0x4->OXM_OF_METADATA[],load:0x6->NXM_NX_REG14[],resubmit(,8)
+ cookie=0xe1b5c263, duration=59.365s, table=0, n_packets=8, n_bytes=636,
priority=100,in_port="8d9e0bc76347e59"
actions=load:0x15->NXM_NX_REG13[],load:0x2->NXM_NX_REG11[],load:0x7->NXM_NX_REG12[],load:0x4->OXM_OF_METADATA[],load:0x7->NXM_NX_REG14[],resubmit(,8)
+
+
+However, we can better understand what table 0 does by looking at its
+logical representation.
+::
+
+ $ ovs-flowviz -i flows.txt -f "table=0" openflow logic
+ Ofproto Flows (logical)
+ └── ** TABLE 0 **
+ ├── priority=180 priority,vlan_tci ---> conjunction ( x 1 )
+ ├── priority=180 priority,conj_id,in_port,vlan_tci --->
load,load,load,load,load,mod_dl_src resubmit(,8), ( x 1 )
+ ├── priority=100 priority,in_port ---> move,move,move resubmit(,40),
( x 2 )
+ ├── priority=100 priority,in_port ---> load,load,load,load,load
resubmit(,8), ( x 16 )
+ ├── priority=100 priority,in_port,vlan_tci --->
load,load,load,load,load resubmit(,8), ( x 1 )
+ ├── priority=100 priority,in_port,dl_vlan --->
strip_vlan,load,load,load,load,load resubmit(,8), ( x 1 )
+ └── priority=0 priority ---> drop, ( x 1 )
+
+
+In only a few logical blocks, we have a good overview of what this table is
+doing. It looks like it's adding metadata based on input ports and vlan
+IDs and mainly sending traffic to table 8.
+
+Let's look at table 8, an in this case, let's filter out the flows that have
+not been hit by actual traffic. This is quite easy to do with the arithmetic
+filtering expressions:
+::
+
+ $ ovs-flowviz -i flows.txt -f "table=8 and n_packets>0" openflow logic
+
+ Ofproto Flows (logical)
+ └── ** TABLE 8 **
+ ├── priority=50 priority,reg14,metadata,dl_dst ---> load
resubmit(,9), ( x 3 )
+ └── priority=50 priority,metadata ---> load,move
resubmit(,73),resubmit(,9), ( x 2 )
+
+At this point, we might find ourselves a bit lost since we may not remember
+what metadata OVN stored in the previous table. Here is where
+``ovs-flowviz``'s OVN integration could come useful. Let's connect to the
+running OVN instance and ask it about the flows we're looking at.
+
+::
+
+ $ export OVN_NB_DB=tcp:172.18.0.4:6641
+ $ export OVN_SB_DB=tcp:172.18.0.4:6642
+ $ ovs-flowviz -i flows.txt -f "table=8 and n_packets>0" openflow logic
--ovn-detrace
+ Ofproto Flows (logical)
+ └── ** TABLE 8 **
+ ├── cookie=0xe10c34ee priority=50 priority,reg14,metadata,dl_dst --->
load resubmit(,9), ( x 1 )
+ │ └── OVN Info
+ │ ├── * Logical datapaths:
+ │ ├── * "ovn_cluster_router"
(366e1c41-0f3d-4420-b796-10692b64e3e4)
+ │ ├── * Logical flow: table=0 (lr_in_admission), priority=50,
match=(eth.mcast && inport == "rtos-ovn-worker2), actions=(xreg0[0..47] =
0a:58:0a:f4:01:01; next;)
+ │ └── * Logical Router Port: rtos-ovn-worker2 mac
0a:58:0a:f4:01:01 networks ['10.244.1.1/24'] ipv6_ra_configs {}
+ ├── cookie=0x11e1adbc priority=50 priority,reg14,metadata,dl_dst --->
load resubmit(,9), ( x 1 )
+ │ └── OVN Info
+ │ ├── * Logical datapaths:
+ │ ├── * "GR_ovn-worker2"
(c07f8387-6479-4e81-9304-9f8e54f81c56)
+ │ ├── * Logical flow: table=0 (lr_in_admission), priority=50,
match=(eth.mcast && inport == "rtoe-GR_ovn-worker2), actions=(xreg0[0..47] =
02:42:ac:12:00:03; next;)
+ │ └── * Logical Router Port: rtoe-GR_ovn-worker2 mac
02:42:ac:12:00:03 networks ['172.18.0.3/16'] ipv6_ra_configs {}
+ ├── cookie=0xf42133f priority=50 priority,reg14,metadata,dl_dst --->
load resubmit(,9), ( x 1 )
+ │ └── OVN Info
+ │ ├── * Logical datapaths:
+ │ ├── * "GR_ovn-worker2"
(c07f8387-6479-4e81-9304-9f8e54f81c56)
+ │ ├── * Logical flow: table=0 (lr_in_admission), priority=50, match=(eth.dst
== 02:42:ac:12:00:03 && inport == "rtoe-GR_ovn-worker2), actions=(xreg0[0..47]
= 02:42:ac:12:00:03; next;)
+ │ └── * Logical Router Port: rtoe-GR_ovn-worker2 mac
02:42:ac:12:00:03 networks ['172.18.0.3/16'] ipv6_ra_configs {}
+ └── cookie=0x43a0327 priority=50 priority,metadata ---> load,move
resubmit(,73),resubmit(,9), ( x 2 )
+ └── OVN Info
+ ├── * Logical datapaths:
+ ├── * "ovn-worker" (24280d0b-fee0-4f8e-ba4f-036a9b9af921)
+ ├── * "ovn-control-plane"
(3262a782-8961-416b-805e-08233e8fda72)
+ ├── * "ext_ovn-worker2"
(3f88dcd2-c56d-478f-a3b1-c7aee2efe967)
+ ├── * "ext_ovn-worker"
(5facbaf0-485d-4cf5-8940-eff9678ef7bb)
+ ├── * "ext_ovn-control-plane"
(8b0aecb6-b05a-48a7-ad09-72524bb91d40)
+ ├── * "join" (e2dc230e-2f2a-4b93-93fa-0fe495163514)
+ ├── * "ovn-worker2" (f7709fbf-d728-4cff-9b9b-150461cc75d2)
+ └── * Logical flow: table=0 (ls_in_check_port_sec),
priority=50, match=(1), actions=(reg0[15] = check_in_port_sec(); next;)
+
+That's way better. ``ovs-flowviz`` has automatically added the `cookie` to the
+logical block key so have more blocks but in exchange, it has looked up each
+cookie on the running OVN databases and inserted the known information on each
+block. So now we see what OVN is trying to do, the logical flow that generated
+each OpenFlow flow and the logical datapath each flow belongs to.
+
+Visualizing datapath flow trees
+-------------------------------
+
+Now, let's see another typical usecase that can lead to eyestrain:
+understanding datapath conntrack recirculations.
+
+OVS makes heavy use of connection tracking and the ``recirc()`` action
+to build complex datapaths. Typically, OVS will insert a flow that,
+when matched, will send the packet through conntrack (using the ``ct`` action)
+and recirculate it with a particular recirculation id (``recirc_id``). Then, a
+flow matching on that ``recirc_id`` will be matched and further process the
+packet. This can happen more than once for a given packet.
+
+This sequential set of events is, however, difficult to visualize when you
+look at a datapath flow dump. Flows are unordered recirculations that need to
+be followed manually (typically, with heavy use of "grep").
+
+For this use-case, ``ovs-flowviz datapath tree`` format can be extremely
+useful. It builds a hierarchical tree based on the ``recirc_id`` matches and
+``recirc()`` actions and indents flows based on it.
+
+Here is an example.
+::
+
+ ── recirc_id(0),in_port(3),eth(...),ipv4(...),tcp(dst=8181),
actions:ct(zone=2,nat),recirc(0x19348)
+ │ ├──
recirc_id(0x19348),in_port(3),ct_state(-new+est-rel-rpl-inv+trk),ct_label(0/0x3),eth(...),eth_type,ipv4(),
actions:ct(zone=27,nat),recirc(0x10)
+ │ │ ├──
recirc_id(0x10),in_port(3),ct_state(-new+est-rel-rpl-inv+trk),eth(...),ipv4(...),
actions:9
+ │ │ ├──
recirc_id(0x10),in_port(3),ct_state(-new+est-rel+rpl-inv+trk),eth(...),ipv4(...),
actions:9
+ │ │ └──
recirc_id(0x10),in_port(3),ct_state(+new-est-rel-rpl-inv+trk),eth(...),ipv4(...),
actions:ct(commit,zone=27,label=0/0x1),9
+ │ └──
recirc_id(0x19348),in_port(3),ct_state(+new-est-rel-rpl-inv+trk),eth(...),ipv4(...),
actions:ct(commit,zone=2,label=0/0x1),ct(zone=27,nat),recirc(0x10)
+ │ ��──
recirc_id(0x10),in_port(3),ct_state(-new+est-rel-rpl-inv+trk),eth(...),ipv4(...),
actions:9
+ │ ├──
recirc_id(0x10),in_port(3),ct_state(-new+est-rel+rpl-inv+trk),eth(...),ipv4(...),
actions:9
+ │ └──
recirc_id(0x10),in_port(3),ct_state(+new-est-rel-rpl-inv+trk),eth(...),ipv4(...),
actions:ct(commit,zone=27,label=0/0x1),9
+
+The above shows a typical conntrack recirculation flow.
+The first flow (with ``recir_id(0)``) sends the packet through conntrack
+system and recirculates with ``recirc_id(0x19348)``.
+Then, based on the ``ct_state`` the packet processing branches out into two
+flows. Each flow resends the packet through conntrack and recirculates the
+packet one more time. Finally, the packet is processed by 3 flows
+on ``recirc_id(10)``.
+
+This 3-stage processing is now very clear.
+
+Note that this format can yield longer outputs since some flows (in this
+example those with ``recirc_id(10)`` can be repeated. However, the result
+is a clear representation of an otherwise difficult to see conntrack
+interaction.
+
+This example shows only a single "subtree". If we use this command to display
+a big flow dump, the output can be lengthy. Here are two (combinable) ways to
+help out.
+
+Plotting datapath trees
+~~~~~~~~~~~~~~~~~~~~~~~
+
+By using the ``ovs-flowviz datapath html`` format, long datapath trees can
+be displayed in an interactive HTML table. The resulting web allows you to
+collapse and expand subtrees so you can focus on what you're looking for.
+
+In addition, the ``ovs-flowviz datapath graph`` format generates a graphviz
+graph definition where each block of flows with the same ``recirc_id`` match
+are arranged together and edges are created to represent recirculations.
+Also, this format comes with further goodies such as displaying the conntrack
+zones which are key to understanding what the datapath is really doing with a
+packet.
+
+These two formats (``html`` and ``graph``) can even be combined. By using the
+``ovs-flowviz datapath graph --html`` command, you'll get an interactive
+HTML table alongside a `svg` graphical representation of the flows. Click on
+a flow on the svg and it'll take you to the corresponding entry in the
+flow table.
+
+
+Filtering
+~~~~~~~~~
+
+Apart from being able to expand and collapse subtrees, we can use filtering.
+
+However, filtering works in a slightly different way compared with OpenFlow
+flows. Instead of just removing non-matching flows, the output
+of a filtered datapath flow tree will show full sub-trees that contain at
+least one flow that satisfies the filter.
+
+For example, let's take the flows in the above example, and let's imagine we
+want to understand what traffic is going out on port ``9``. We could run
+the tool as:
+::
+
+ $ ovs-appctl dpctl/dump-flows | ovs-flowviz -f "output.port=9" datapath tree
+
+The resulting flow tree will contain all of the flows above, even those
+with ``recirc_id(0)`` and ``recirc_id(19348)`` that don't actually output
+traffic to port ``9``. Why? because they are all part of a subtree that
+contains flows that do output packets on port ``9``
+
+That way, we see the "full picture" of how traffic on port ``9`` is being
+processed.
+
+.. _ovs-flowviz(8): https://docs.openvswitch.org/en/latest/ref/ovs-flowviz.8
diff --git a/Documentation/topics/index.rst b/Documentation/topics/index.rst
index f239fcf83..9ddb145dd 100644
--- a/Documentation/topics/index.rst
+++ b/Documentation/topics/index.rst
@@ -58,3 +58,4 @@ OVS
userspace-checksum-offloading
userspace-tx-steering
usdt-probes
+ flow-visualization
--
2.44.0
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