### Simulate Hypervisors and Configure OVN Ports

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/ref/ovn-sim.1.md

This example demonstrates simulating multiple hypervisors, attaching them to a network, and configuring OVN logical ports. It involves starting OVN, adding a logical switch, and iterating through hypervisors to set up bridges, attach them, and add logical switch ports with MAC and IP addresses.

```bash
ovn_start
ovn-nbctl ls-add lsw0
net_add n1
for i in 0 1; do
    sim_add hv$i
    as hv$i
    ovs-vsctl add-br br-phys
    ovn_attach n1 br-phys 192.168.`expr $i + 1`
    ovs-vsctl add-port br-int vif$i -- \
        set Interface vif$i external-ids:iface-id=lp$i
    ovn-nbctl lsp-add lsw0 lp$i
    ovn-nbctl lsp-set-addresses lp$i f0:00:00:00:00:0$i
done
```

--------------------------------

### Configure OVN with Custom Installation Paths

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/general.md

Customize the installation directories for OVN files, state, and configuration. This example sets the prefix to /usr, localstatedir to /var, and sysconfdir to /etc.

```bash
$ ./configure --prefix=/usr --localstatedir=/var --sysconfdir=/etc
```

--------------------------------

### Install OVN

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/general.md

Run 'make install' to install OVN executables and manpages. By default, installation occurs under /usr/local.

```bash
$ sudo make install
```

--------------------------------

### Install OVN Host Package

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/debian.md

Installs the OVN controller component for each host or hypervisor using apt-get.

```bash
$ sudo apt-get install ovn-host
```

--------------------------------

### Install Python Dependencies with Pip

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/documentation.md

Sets up a Python virtual environment and installs project dependencies from requirements.txt using pip.

```bash
$ python3 -m venv .venv
$ source .venv/bin/activate
$ pip install -r Documentation/requirements.txt
```

--------------------------------

### Start OVN Controller

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/howto/docker.md

Command to start the OVN controller. This command needs to be executed on every boot.

```bash
$ /usr/share/ovn/scripts/ovn-ctl start_controller
```

--------------------------------

### Install git-pw Tool

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/internals/patchwork.md

Install the git-pw tool using pip. This command should be run with the --user flag to install it in the user's home directory.

```default
$ pip install --user git-pw
```

--------------------------------

### Install OVN Host Node Packages

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/fedora.md

Use 'dnf' to install the 'ovn-host' package on each host or hypervisor to run ovn-controller.

```bash
$ sudo dnf install ovn-host
```

--------------------------------

### DevStack Initialization Output Example

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-openstack.md

This is an example of the expected output upon successful completion of stack.sh, showing host IP, dashboard URL, and service endpoints.

```text
This is your host IP address: 172.16.189.6
This is your host IPv6 address: ::1
Horizon is now available at http://172.16.189.6/dashboard
Keystone is serving at http://172.16.189.6/identity/
The default users are: admin and demo
The password: password
2017-03-09 15:10:54.117 | stack.sh completed in 2110 seconds.
```

--------------------------------

### Start OVN Sandbox Environment

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-sandbox.md

Run this command to initialize the OVN sandbox environment. It sets up databases, starts daemons, and makes utilities available.

```bash
$ make sandbox
```

--------------------------------

### Install Additional OVN Packages

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/fedora.md

Install shared components, VTEP support, or bridge controller packages using 'dnf'.

```bash
$ sudo dnf install ovn                 # shared components
```

```bash
$ sudo dnf install ovn-vtep            # VTEP gateway support
```

```bash
$ sudo dnf install ovn-br-controller   # bridge controller
```

--------------------------------

### Create Network and Connect Container

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/howto/docker.md

This example demonstrates creating a new logical switch and then connecting an existing container to it.

```bash
$ docker network create -d openvswitch --subnet=192.168.2.0/24 bar
$ docker network connect bar busybox
```

--------------------------------

### Install Sphinx on Debian/Ubuntu

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/documentation.md

Installs the Sphinx documentation generator using the apt-get package manager.

```bash
$ sudo apt-get install python3-sphinx
```

--------------------------------

### Install Sphinx on RHEL/Fedora

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/documentation.md

Installs the Sphinx documentation generator using the dnf package manager.

```bash
$ sudo dnf install python3-sphinx
```

--------------------------------

### Install OVN RPM Packages

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/fedora.md

Install the built OVN RPM packages using 'rpm -i'. Superuser privileges are required for installation.

```bash
$ sudo rpm -i ovn-*.rpm
```

--------------------------------

### Install Development Tools and Build Dependencies

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/fedora.md

Install RPM tools and generic build dependencies required for building OVN RPM packages.

```bash
$ sudo dnf install @'Development Tools' rpm-build dnf-plugins-core
```

--------------------------------

### Start OVN Daemons using ovn-ctl

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/general.md

Use the ovn-ctl script to start OVN northd and controller daemons. Ensure the script is in your PATH.

```bash
$ export PATH=$PATH:/usr/local/share/ovn/scripts
$ ovn-ctl start_northd
$ ovn-ctl start_controller
```

--------------------------------

### Run OVN Setup Script

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-sandbox.md

Execute the ovn-setup.sh script from the OVN source tree to automate the creation of OVN resources.

```bash
$ ./ovn-setup.sh
```

--------------------------------

### Install Debian Packaging Tools and OVN Build Dependencies

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/debian.md

Installs essential tools for Debian packaging and the specific build dependencies required for OVN.

```bash
$ sudo apt-get install build-essential fakeroot devscripts
```

```bash
$ sudo apt-get install graphviz autoconf automake bzip2 \    debhelper dh-autoreconf dh-python libssl-dev libtool \    openssl procps python3-all python3-sphinx \    python3-twisted python3-zope.interface \    libunbound-dev libunwind-dev
```

--------------------------------

### Start Interconnection Databases

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-interconnection.md

Starts the OVN IC-NB and IC-SB databases. Use '--db-ic-nb-create-insecure-remote=yes' and '--db-ic-sb-create-insecure-remote=yes' for standalone mode with TCP connections.

```bash
$ ovn-ctl [options] start_ic_ovsdb
```

```bash
$ ovn-ctl --db-ic-nb-create-insecure-remote=yes \
          --db-ic-sb-create-insecure-remote=yes start_ic_ovsdb
```

--------------------------------

### Install Required Python Packages

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/howto/docker.md

Install the 'python-neutronclient' and 'Flask' libraries required for the OVN Docker network driver.

```bash
$ pip install python-neutronclient
$ pip install Flask

```

--------------------------------

### Start OVN Controller and Connect to OVSDB Relay

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-ovsdb-relay.md

Configures the ovn-controller to connect to the OVSDB Relay using SSL and then starts the ovn-controller service.

```bash
ovs-vsctl set external_ids:ovn-remote="ssl:127.0.0.1:6642"
/usr/share/ovn/scripts/ovn-ctl start_controller
```

--------------------------------

### Start OVN Northbound Daemon using ovn-ctl

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/general.md

Initiate the ovn-northd service using the ovn-ctl utility. Ensure the script is in your PATH.

```bash
> $ export PATH=$PATH:/usr/local/share/ovn/scripts
> $ ovn-ctl start_northd
```

--------------------------------

### Install Additional OVN Packages

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/debian.md

Installs supplementary OVN packages like shared components and VTEP gateway support.

```bash
$ sudo apt-get install ovn-common              # shared components
```

```bash
$ sudo apt-get install ovn-controller-vtep     # VTEP gateway support
```

--------------------------------

### Install OVN Specific Build Dependencies

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/fedora.md

Install OVN-specific build dependencies using 'dnf builddep' with the temporary SPEC file.

```bash
$ sudo dnf builddep /tmp/ovn.spec
```

--------------------------------

### OVN Trace Ingress Pipeline Example

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-openstack.md

Example output of an OVN trace showing the ingress pipeline processing for an IPv6 packet.

```text
ingress(dp="n1", inport="ap")
-----------------------------
 0. ls_in_port_sec_l2 (northd.c:3234): inport == "ap" && eth.src == {fa:16:3e:a9:4c:c7}, priority 50, uuid 6dcc418a
    next;
 1. ls_in_port_sec_ip (northd.c:2390): inport == "ap" && eth.src == fa:16:3e:a9:4c:c7 && ip6.src == {fe80::f816:3eff:fea9:4cc7, fc11::5}, priority 90, uuid 604810ea
    next;
 3. ls_in_pre_acl (northd.c:2646): ip, priority 100, uuid 46c089e6
    reg0[0] = 1;
    next;
 5. ls_in_pre_stateful (northd.c:2764): reg0[0] == 1, priority 100, uuid d1941634
    ct_next;

ct_next(ct_state=est|trk /* default (use --ct to customize) */)
---------------------------------------------------------------
 6. ls_in_acl (northd.c:2925): !ct.new && ct.est && !ct.rpl && ct_label.blocked == 0 && (inport == "ap" && ip6), priority 2002, uuid 7fdd607e
    next;
13. ls_in_l2_lkup (northd.c:3529): eth.dst == fa:16:3e:ef:2f:8b, priority 50, uuid e1d87fc5
    outport = "ad952e";
    output;

egres(dp="n1", inport="ap", outport="ad952e")
----------------------------------------------
 1. ls_out_pre_acl (northd.c:2626): ip && outport == "ad952e", priority 110, uuid 88f68988
    next;
 8. ls_out_port_sec_l2 (northd.c:3654): outport == "ad952e", priority 50, uuid 5935755e
    output;
    /* output to "ad952e", type "patch" */

ingress(dp="r", inport="lrp-ad952e")
------------------------------------
 0. lr_in_admission (northd.c:4071): eth.dst == fa:16:3e:ef:2f:8b && inport == "lrp-ad952e", priority 50, uuid ddfeb712
    next;
 5. lr_in_ip_routing (northd.c:3782): ip6.dst == fc22::/64, priority 129, uuid cc2130ec
    ip.ttl--;
    xxreg0 = ip6.dst;
    xxreg1 = fc22::1;
    eth.src = fa:16:3e:06:de:ad;
    outport = "lrp-1a8162";
    flags.loopback = 1;
    next;

```

--------------------------------

### OVN Scale Test Setup

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/ref/ovn-sim.1.md

A primitive OVN scale test setup that simulates a large number of hypervisors and configures them with clustered OVN databases. It uses background processes for adding hypervisors and configures logical ports with dynamically generated MAC addresses.

```bash
n=200; export n
ovn_start --sbdb-model=clustered
net_add n1
ovn-nbctl ls-add br0
for i in `seq $n`; do
    (sim_add hv$i
    as hv$i
    ovs-vsctl add-br br-phys
    y=$(expr $i / 256)
    x=$(expr $i % 256)
    ovn_attach n1 br-phys 192.168.$y.$x
    ovs-vsctl add-port br-int vif$i -- \
        set Interface vif$i external-ids:iface-id=lp$i) &
    case $i in
        *50|*00) echo $i; wait ;;
    esac
done
wait
for i in `seq $n`; do
    yy=$(printf %02x $(expr $i / 256))
    xx=$(printf %02x $(expr $i % 256))
    ovn-nbctl lsp-add br0 lp$i
    ovn-nbctl lsp-set-addresses br0 lp$i f0:00:00:00:$yy:$xx
done
```

--------------------------------

### Install Git on CentOS 7 (Shell)

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-openstack.md

Install the Git package on a CentOS 7 system. This is a prerequisite for cloning DevStack and Neutron repositories.

```shell
$ sudo yum install git
```

--------------------------------

### Install OVN Central Node Packages

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/fedora.md

Use 'dnf' to install the 'ovn-central' package for a central OVN node that runs databases and ovn-northd.

```bash
$ sudo dnf install ovn-central
```

--------------------------------

### Example Patch Format

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/internals/contributing/submitting-patches.md

This is an example of a patch in `diff -up` format, generated using Git with `-M -C` options. Ensure patches are inline in emails and follow the project's coding style.

```default
From fa29a1c2c17682879e79a21bb0cdd5bbe67fa7c0 Mon Sep 17 00:00:00 2001
From: Jesse Gross <jesse@nicira.com>
Date: Thu, 8 Dec 2011 13:17:24 -0800
Subject: [PATCH] datapath: Alphabetize include/net/ipv6.h compat header.

Signed-off-by: Jesse Gross <jesse@nicira.com>
---
 datapath/linux/Modules.mk |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/datapath/linux/Modules.mk b/datapath/linux/Modules.mk
index fdd952e..f6cb88e 100644
--- a/datapath/linux/Modules.mk
+++ b/datapath/linux/Modules.mk
@@ -56,11 +56,11 @@ openvswitch_headers +=
    linux/compat/include/net/dst.h \
    linux/compat/include/net/genetlink.h \
    linux/compat/include/net/ip.h \
+   linux/compat/include/net/ipv6.h \
    linux/compat/include/net/net_namespace.h \
    linux/compat/include/net/netlink.h \
    linux/compat/include/net/protocol.h \
    linux/compat/include/net/route.h \
-   linux/compat/include/net/ipv6.h \
    linux/compat/genetlink.inc

 both_modules += brcompat
--
1.7.7.3

```

--------------------------------

### Get git-pw Help

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/internals/patchwork.md

Display help information for the git-pw command to understand available subcommands and options.

```default
$ git pw --help
```

--------------------------------

### Start OVN Northbound ovsdb-server

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/general.md

Manually start the OVN Northbound ovsdb-server, configuring it to use the created database, listen on a Unix domain socket, and use SSL/TLS settings. Omit SSL/TLS options if built without support.

```bash
$ sudo mkdir -p /usr/local/var/run/ovn
$ sudo ovsdb-server /usr/local/etc/ovn/ovnnb_db.db --remote=punix:/usr/local/var/run/ovn/ovnnb_db.sock \
     --remote=db:OVN_Northbound,NB_Global,connections \
     --private-key=db:OVN_Northbound,SSL,private_key \
     --certificate=db:OVN_Northbound,SSL,certificate \
     --bootstrap-ca-cert=db:OVN_Northbound,SSL,ca_cert \
     --pidfile=/usr/local/var/run/ovn/ovnnb-server.pid --detach --log-file=/usr/local/var/log/ovn/ovnnb-server.log
```

--------------------------------

### Start and Enable Firewall for IPsec

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-ipsec.md

On Fedora, RHEL, and CentOS, start and enable the firewall service to allow ESP and IKE traffic for IPsec.

```bash
# systemctl start firewalld
# firewall-cmd --add-service ipsec
```

```bash
# systemctl enable firewalld
# firewall-cmd --permanent --add-service ipsec
```

--------------------------------

### Start OVN Controller Service

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/general.md

Start the `ovn-controller` service on each chassis. This service connects to the local OVS instance and requires specific configuration keys like `system-id`, `ovn-remote`, `ovn-encap-type`, and `ovn-encap-ip`.

```bash
$ ovn-controller --pidfile --detach --log-file
```

--------------------------------

### Start Docker Daemon with Cluster Store

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/howto/docker.md

Start the Docker daemon with a distributed key-value store like Consul for multi-host networking. Replace `$HOST_IP` with your host's IP address.

```bash
$ docker daemon --cluster-store=consul://127.0.0.1:8500 \
    --cluster-advertise=$HOST_IP:0
```

--------------------------------

### Start OVN Databases and northd

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/ref/ovn-sim.1.md

Initializes and starts the central OVN databases (northbound and southbound) and the ovn-northd process. Supports different database models like standalone, backup, and clustered.

```bash
ovn_start
```

```bash
ovn_start --nbdb-model=clustered --nbdb-servers=5 --sbdb-model=backup
```

--------------------------------

### OVS Commit History Example

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/internals/ovs_submodule.md

Illustrates a simplified OVS commit history to explain submodule versioning for OVN releases. This is a conceptual example, not executable code.

```text
         (Newest)
         Commit 4
            |
            |
         Commit 2 ------------------------------- Commit 3
(used to create OVS branch-Y)      (latest stable release on OVS branch-Y)
            |
            |
         Commit 1
         (Oldest)
```

--------------------------------

### Start OVN Southbound ovsdb-server

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/general.md

Manually start the OVN Southbound ovsdb-server, configuring it to use the created database, listen on a Unix domain socket, and use SSL/TLS settings. Omit SSL/TLS options if built without support.

```bash
$ sudo ovsdb-server /usr/local/etc/ovn/ovnsb_db.db --remote=punix:/usr/local/var/run/ovn/ovnsb_db.sock \
     --remote=db:OVN_Southbound,SB_Global,connections \
     --private-key=db:OVN_Southbound,SSL,private_key \
     --certificate=db:OVN_Southbound,SSL,certificate \
     --bootstrap-ca-cert=db:OVN_Southbound,SSL,ca_cert \
     --pidfile=/usr/local/var/run/ovn/ovnsb-server.pid --detach --log-file=/usr/local/var/log/ovn/ovnsb-server.log
```

--------------------------------

### Start Intermediate OVSDB Relay in Two-Tier Multi-Group Deployment

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-ovsdb-relay.md

Starts an intermediate OVSDB Relay server in a two-tier multi-group setup. The '--db-sb-relay-use-remote-in-db=no' option is crucial here.

```bash
/usr/share/ovn/scripts/ovn-ctl start_sb_relay_ovsdb \
  --db-sb-relay-remote=tcp:127.0.0.1:16642 \
  --db-sb-relay-use-remote-in-db=no \
  --ovn-sb-relay-db-ssl-key=/path/to/ovsdb/relay/ssl-key.pem \
  --ovn-sb-relay-db-ssl-cert=/path/to/ovsdb/relay/ssl-cert.pem \
  --ovn-sb-relay-db-ssl-ca-cert=/path/to/ovsdb/relay/ssl-ca-cert.pem \
  -- --remote=pssl:26642
```

--------------------------------

### Copy firewalld Service Files from Source

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/howto/firewalld.md

Copy the firewalld service XML files to the firewalld services directory when installing OVN from source.

```bash
$ cp rhel/usr_lib_firewalld_services_ovn-central-firewall-service.xml \
/etc/firewalld/services/
$ cp rhel/usr_lib_firewalld_services_ovn-host-firewall-service.xml \
/etc/firewalld/services/
```

--------------------------------

### Get VM Instance ID

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/howto/docker.md

Retrieves the ID of a VM instance, which is a prerequisite for identifying its network interface in the underlay mode setup.

```bash
$ nova list
```

--------------------------------

### Display Configure Help Options

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/general.md

Invoke the configure script with the --help option to see all available configuration options.

```bash
$ ./configure --help
```

--------------------------------

### Start OVN Docker Overlay Driver

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/howto/docker.md

Starts the Open vSwitch driver for Docker networking. This driver replaces the default Linux bridge and enables OVN's logical networking features for containers. Ensure `$OVS_PYTHON_LIBS_PATH` is correctly set if OVS Python modules were not installed via standard packages or pip.

```bash
$ PYTHONPATH=$OVS_PYTHON_LIBS_PATH ovn-docker-overlay-driver --detach
```

--------------------------------

### IPv4 NAT Rule Example

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/ref/ovn-logical-flows.7.md

Flow for distributed NAT rules with IPv4, matching source IP and chassis residency.

```ovn-sbctl
priority 90 ip4.src = A && is_chassis_resident(P) \
    actions get_arp(outport, reg0); next;
```

--------------------------------

### IPv6 NAT Rule Example

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/ref/ovn-logical-flows.7.md

Flow for distributed NAT rules with IPv6, matching source IP and chassis residency.

```ovn-sbctl
priority 90 ip6.src = A && is_chassis_resident(P) \
    actions get_nd(outport, xxreg0); next;
```

--------------------------------

### Build and Run ovn-sim

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/ref/ovn-sim.1.md

This snippet shows the steps to clone, build, and run ovn-sim from source. It requires building both Open vSwitch and OVN, and configuring OVN with the OVS source directory.

```bash
git clone https://github.com/openvswitch/ovs.git
cd ovs
./boot.sh && ./configure && make
cd ..
git clone https://github.com/ovn-org/ovn.git
cd ovn
./boot.sh && ./configure --with-ovs-source=${PWD}/../ovs
make
utilities/ovn-sim
```

--------------------------------

### Set Open vSwitch System ID

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/howto/docker.md

Ensures each Open vSwitch instance has a unique, persistent identifier. This is automatically handled by distribution packages or `ovs-ctl`, but manual setup is required for manual Open vSwitch starts.

```bash
$ id_file=/etc/openvswitch/system-id.conf
$ test -e $id_file || uuidgen > $id_file
$ ovs-vsctl set Open_vSwitch . external_ids:system-id=$(cat $id_file)
```

--------------------------------

### Install Non-PAE Kernel for 32-bit VM (Shell)

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-openstack.md

If using a 32-bit VM, install the non-PAE kernel and reboot. This is necessary for DevStack to install properly on such systems.

```shell
$ sudo yum install kernel-core kernel-devel
$ sudo reboot
```

--------------------------------

### Prepare Open vSwitch Submodule

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/general.md

Before configuring OVN, prepare the Open vSwitch sources using the included submodule. This involves updating the submodule, navigating into the ovs directory, and running its build and configure scripts.

```bash
$ git submodule update --init
$ cd ovs
$ ./boot.sh
$ ./configure
$ make
$ cd ..
```

--------------------------------

### Configure OVN Build

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/general.md

Run the configure script to prepare OVN for building. This is a standard step after bootstrapping.

```bash
$ ./configure
```

--------------------------------

### Initialize DevStack

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-openstack.md

Run the stack.sh script to initialize DevStack and download necessary software. This process can take a significant amount of time on the first run.

```bash
$ ./stack.sh
```

--------------------------------

### Bootstrap OVN from Source

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/general.md

Run this script if you have pulled OVN sources directly from a Git tree or obtained a Git tree snapshot. This builds the 'configure' script.

```bash
$ ./boot.sh
```

--------------------------------

### Start OVS Traffic vSwitchd

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/topics/test-development.md

The `OVS_TRAFFIC_VSWITCHD_START` macro initializes `ovsdb-server` and `ovs-vswitchd`, creates a bridge `br0`, and allows for additional `ovs-vsctl` commands. Use `=override` as the third argument to enable 'system' devices.

```shell
OVS_TRAFFIC_VSWITCHD_START([vsctl-args], [vsctl-output], [=override])
```

--------------------------------

### Start OVN Cluster Mode Containers (Node 1)

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/general.md

Initiate OVN cluster mode on the first node by running `ovn-nb-cluster-create`, `ovn-sb-cluster-create`, and `ovn-northd-cluster` Docker containers. Configure host IP, database ports, and specify the database connection strings for all nodes.

```bash
$ docker run -e "host_ip=<host_ip>" -e "nb_db_port=<port>" -itd \
  --name=ovn-nb-raft --net=host --privileged <docker_repo>:<tag> \
  ovn-nb-cluster-create

$ docker run -e "host_ip=<host_ip>" -e "sb_db_port=<port>" -itd \
  --name=ovn-sb-raft --net=host --privileged <docker_repo>:<tag> \
  ovn-sb-cluster-create

$ docker run -e "OVN_NB_DB=tcp:<node1>:6641,tcp:<node2>:6641,\n  tcp:<node3>:6641" -e "OVN_SB_DB=tcp:<node1>:6642,tcp:<node2>:6642,\n  tcp:<node3>:6642" -itd --name=ovn-northd-raft <docker_repo>:<tag> \
  ovn-northd-cluster
```

--------------------------------

### Start OVN Interconnection Services

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/general.md

Start the OVN Interconnection (OVN IC) databases and daemon if OVN IC is used in the deployment.

```bash
$ ovn-ctl start_ic_ovsdb
$ ovn-ctl start_ic
```

--------------------------------

### Start Simulated OVN Instance

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/topics/test-development.md

Use `sim_add` to create a new simulated Open vSwitch instance. Subsequent commands can then be run within this instance's context using the `as` command.

```shell
sim_add hv0           # Create sandbox hv0.
as hv0                # Set hv0 as default sandbox.
ovs-vsctl add-br br0  # Add bridge br0 inside hv0.
```

```shell
sim_add hv0
as hv0 ovs-vsctl add-br br0
```

--------------------------------

### Create SSH Keypair for VMs

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-openstack.md

Creates an SSH keypair named 'demo' and saves the private key to ~/id_rsa_demo. Ensure the private key has restricted permissions.

```bash
$ openstack keypair create demo > ~/id_rsa_demo
$ chmod 600 ~/id_rsa_demo
```

--------------------------------

### Install OVN Central Node Package

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/debian.md

Installs the OVN central node components, including OVN databases and ovn-northd, using apt-get.

```bash
$ sudo apt-get install ovn-central
```

--------------------------------

### Start OVN Northbound Daemon

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/general.md

Start the `ovn-northd` daemon, specifying connection to OVN DB servers via Unix domain socket.

```bash
$ ovn-northd --pidfile --detach --log-file
```

--------------------------------

### Prepare OVN Submodules and Configure OVN

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/documentation.md

Updates OVN submodules, configures the OVS submodule, and then configures the main OVN project before building documentation.

```bash
$ git submodule update --init
$ cd ovs
$ ./boot.sh && ./configure
$ cd ..
$ ./boot.sh && ./configure
```

--------------------------------

### Graphic Table Example in reStructuredText

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/internals/contributing/documentation-style.md

This example demonstrates how to create a graphic table in reStructuredText for displaying structured data. The table role can be omitted.

```rst
.. table:: OVS-Linux kernel compatibility

  ============ ==============
  Open vSwitch Linux kernel
  ============ ==============
  1.4.x        2.6.18 to 3.2
  1.5.x        2.6.18 to 3.2
  1.6.x        2.6.18 to 3.2
  ============ ==============

```

--------------------------------

### Configure Guest Architecture in local.conf

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-openstack.md

If using a 32-bit i386 guest, specify the CIRROS_ARCH in local.conf. This ensures compatibility with the guest environment.

```default
CIRROS_ARCH=i386
```

--------------------------------

### Add Swap Space in VM (Shell)

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-openstack.md

Use these commands to add 2GB of swap space to a VM with limited RAM, preventing out-of-memory errors during DevStack setup. Ensure to update /etc/fstab for persistence.

```shell
$ sudo dd if=/dev/zero of=/swapfile bs=1M count=2048
$ sudo mkswap /swapfile
$ sudo swapon /swapfile
```

```shell
/swapfile swap swap defaults 0 0
```

--------------------------------

### Start OVSDB Southbound Relay and Connect to Cluster

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-ovsdb-relay.md

Starts the OVSDB Southbound Relay and connects it to the OVSDB cluster. Ensure SSL certificates are correctly configured.

```bash
/usr/share/ovn/scripts/ovn-ctl start_sb_relay_ovsdb \
  --db-sb-relay-remote=tcp:127.0.0.1:16642 \
  --ovn-sb-relay-db-ssl-key=/path/to/ovsdb/relay/ssl-key.pem \
  --ovn-sb-relay-db-ssl-cert=/path/to/ovsdb/relay/ssl-cert.pem \
  --ovn-sb-relay-db-ssl-ca-cert=/path/to/ovsdb/relay/ssl-ca-cert.pem
```

--------------------------------

### Create Logical Topology for Gateway Router

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/topics/dynamic-routing/configuration-examples.md

Sets up the basic logical router and switch infrastructure for a gateway scenario. Includes router ports for internal and fabric networks, and a localnet port for physical connectivity.

```bash
$ ovn-nbctl lr-add lr-gw
$ ovn-nbctl ls-add ls-internal
$ ovn-nbctl ls-add ls-fabric

# Router port toward the internal network.
$ ovn-nbctl lrp-add lr-gw lrp-internal \
    00:00:00:00:00:01 10.0.0.1/24
$ ovn-nbctl lsp-add-router-port ls-internal \
    lsp-internal-to-gw lrp-internal

# Router port toward the fabric.
$ ovn-nbctl lrp-add lr-gw lrp-fabric \
    00:00:00:00:00:02 192.168.1.1/24
$ ovn-nbctl lsp-add-router-port ls-fabric \
    lsp-fabric-to-gw lrp-fabric

# Localnet port for physical connectivity.
$ ovn-nbctl lsp-add-localnet-port ls-fabric \
    lsp-fabric-ln physnet-fabric
```

--------------------------------

### Start Last-Level OVSDB Relay in Two-Tier Multi-Group Deployment

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-ovsdb-relay.md

Starts the last-level OVSDB Relay servers that ovn-controllers will connect to. SSL certificates are required for secure communication.

```bash
/usr/share/ovn/scripts/ovn-ctl start_sb_relay_ovsdb \
  --db-sb-relay-remote=tcp:127.0.0.1:26642 \
  --ovn-sb-relay-db-ssl-key=/path/to/ovsdb/relay/ssl-key.pem \
  --ovn-sb-relay-db-ssl-cert=/path/to/ovsdb/relay/ssl-cert.pem \
  --ovn-sb-relay-db-ssl-ca-cert=/path/to/ovsdb/relay/ssl-ca-cert.pem
```

--------------------------------

### Initialize OVN Databases

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/intro/install/general.md

Initialize the OVN Northbound and Southbound databases. This is typically done once after creating the databases.

```bash
$ ovn-nbctl --no-wait init
$ ovn-sbctl init
```

--------------------------------

### Start OVSDB Southbound Relay with SSL/TLS

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-ovsdb-relay.md

Starts the OVSDB Southbound Relay using SSL/TLS for communication with the cluster and configures ovn-controller to connect to the relay via SSL/TLS.

```bash
# start OVSDB Southbound Relay and connect to cluster
/usr/share/ovn/scripts/ovn-ctl start_sb_relay_ovsdb \
  --db-sb-relay-remote=tcp:127.0.0.1:16642 \
  --ovn-sb-relay-db-ssl-key=/path/to/ovsdb/relay/ssl-key.pem \
  --ovn-sb-relay-db-ssl-cert=/path/to/ovsdb/relay/ssl-cert.pem \
  --ovn-sb-relay-db-ssl-ca-cert=/path/to/ovsdb/relay/ssl-ca-cert.pem \
  -- --remote=pssl:6642

# start ovn-controller and connect to OVSDB Relay
ovs-vsctl set external_ids:ovn-remote="ssl:127.0.0.1:6642"
ovs-vsctl set-ssl <...>
/usr/share/ovn/scripts/ovn-ctl start_controller
```

--------------------------------

### Create and Configure Router

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-openstack.md

Commands to create an OpenStack router and attach it to existing subnets.

```bash
$ openstack router create r
$ openstack router add subnet r n1subnet
$ openstack router add subnet r n2subnet
```

--------------------------------

### OVN Logical Flow Example

Source: https://github.com/ovn-org/ovn/blob/main/Documentation/tutorials/ovn-openstack.md

Example of an OVN logical flow entry, showing table, priority, match conditions, and actions. This is obtained using `ovn-sbctl lflow-list`.

```text
Datapath: "neutron-5b6baf" aka "n1" (a8a758)  Pipeline: ingress
  table=0 (ls_in_port_sec_l2  ), priority=50   , match=(inport == "820c08" && eth.src == {fa:16:3e:a9:4c:c7}), action=(next;)
```