Name

ovs-sim -- Open vSwitch simulator environment

Synopsis

ovs-sim [option]... [script]...

Description

ovs-sim provides a convenient environment for running one or more Open vSwitch instances and related software in a sandboxed simulation environment.

To use ovs-sim, first build Open vSwitch, then invoke it directly from the build directory, e.g.:

git clone https://github.com/openvswitch/ovs.git
cd ovs
./configure
make
utilities/ovs-sim

When invoked in the most ordinary way as shown above, ovs-sim does the following:

Creates a directory sandbox as a subdirectory of the current directory (first destroying such a directory if it already exists) and cds into that directory.
Installs all of the Open vSwitch manpages into a man subdirectory of sandbox and adjusts the MANPATH environment variable so that man and other manpage viewers can find them.
Creates a simulated Open vSwitch named main and sets it up as the default target for OVS commands, as if the following ovs-sim commands had been run:
```
          sim_add main
          as main
        
```
See Commands, below, for an explanation.
Runs any scripts specified on the command line (see Options below). The scripts can use arbitrary Bash syntax, plus the additional commands described under Commands, below.
If no scripts were specified, or if or was specified, invokes an interactive Bash subshell. The user can use arbitrary Bash commands, plus the additional commands described under Commands, below.

ovs-sim and the sandbox environment that it creates does not require superuser or other special privileges. Generally, it should not be run with such privileges.

Options

ovs-sim accepts the following options and arguments:

script: Runs script, which should be a Bash script, within a subshell after initializing. If multiple script arguments are given, then they are run in the order given. If any script exits with a nonzero exit code, then ovs-sim exits immediately with the same exit code.

: By default, if any script is specified, ovs-sim exits as soon as the scripts finish executing. With this option, or if no scripts are specified, ovs-sim instead starts an interactive Bash session.

Commands

Scripts and interactive usage may use the following commands implemented by ovs-sim. They are implemented as Bash shell functions exported to subshells.

Basic Commands

These are the basic commands for working with sandboxed Open vSwitch instances.

sim_add sandbox

Starts a new simulated Open vSwitch instance named sandbox. Files related to the instance, such as logs, databases, sockets, and pidfiles, are created in a subdirectory also named sandbox. Afterward, the as command (see below) can be used to run Open vSwitch utilities in the context of the new sandbox.

The new sandbox starts out without any bridges. Use ovs-vsctl in the context of the new sandbox to create a bridge, e.g.:

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

The Open vSwitch instances that sim_add create enable ``dummy'' devices. This means that bridges and interfaces can be created with type dummy to indicate that they should be totally simulated, without any reference to system entities. In fact, ovs-sim also configures Open vSwitch so that the default system type of bridges and interfaces are replaced by dummy devices. Other types of devices, however, retain their usual functions, which means that, e.g., vxlan tunnels still act as tunnels (see README-native-tunneling.md).

as sandbox

Sets sandbox as the default simulation target for Open vSwitch commands (e.g. ovs-vsctl, ovs-ofctl, ovs-appctl).

This command updates the beginning of the shell prompt to indicate the new default target.

as sandbox command arg...

Runs the given command with sandbox as the simulation target, e.g. as hv0 ovs-vsctl add-br br0 runs ovs-vsctl add-br br0 within sandbox hv0. The default target is unchanged.

Interconnection Network Commands

When multiple sandboxed Open vSwitch instances exist, one will inevitably want to connect them together. These commands allow for that. Conceptually, an interconnection network is a switch that ovs-sim makes it easy to plug into other switches in other sandboxed Open vSwitch instances. Interconnection networks are implemented as bridges in the main switch that ovs-sim creates by default, so to use interconnection networks please avoid working with main directly.

net_add network: Creates a new interconnection network named network.
net_attach network bridge: Adds a new port to bridge in the default sandbox (as set with as) and plugs it into the network interconnection network. network must already have been created by a previous invocation of net_add. The default sandbox must not be main.

OVN Commands

These commands interact with OVN, the Open Virtual Network.

ovn_start: Creates and initializes the central OVN databases (both ovn-sb(5) and ovn-nb) and starts an instance of ovsdb-server for each one. Also starts an instance of ovn-northd.
ovn_attach network bridge ip [masklen]: First, this command attaches bridge to interconnection network network, just like net_attach network bridge. Second, it configures (simulated) IP address ip (with network mask length masklen, which defaults to 24) on bridge. Finally, it configures the Open vSwitch database to work with OVN and starts ovn-controller.

Examples

The following creates a pair of Open vSwitch instances hv0 and hv1, adds a port named vif0 or vif1, respectively, to each one, and then connects the two through an interconnection network n1:

net_add n1
for i in 0 1; do
    sim_add hv$i
    as hv$i ovs-vsctl add-br br0 -- add-port br0 vif$i
    as hv$i net_attach n1 br0
done

Here's an extended version that also starts OVN:

ovn_start
ovn-nbctl lswitch-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 192.168.0.`expr $i + 1`
    ovs-vsctl add-port br-int vif$i -- set Interface vif$i external-ids:iface-id=lp$i
    ovn-nbctl lport-add lsw0 lp$i
    ovn-nbctl lport-set-addresses lp$i f0:00:00:00:00:0$i
done

Here's a primitive OVN ``scale test'' (adjust the scale by changing n in the first line :

n=200; export n
ovn_start
net_add n1
ovn-nbctl lswitch-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 $i % 256))
    ovn-nbctl lport-add br0 lp$i
    ovn-nbctl lport-set-addresses lp$i f0:00:00:00:$yy:$xx
done

When the scale test has finished initializing, you can watch the logical ports come up with a command like this:

watch 'for i in `seq $n`; do if test `ovn-nbctl lport-get-up lp$i` != up; then echo $i; fi; done'