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OpenStack Neutron ML2 and Cumulus Linux

The Modular Layer 2 (ML2) plugin is a framework that allows OpenStack Networking to use a variety of non-vendor-specific layer 2 networking technologies. The ML2 framework simplifies adding support for new layer 2 networking technologies and enables dynamic provisioning of VLAN/VXLAN on switches in an OpenStack environment instead of manually provisioning layer 2 connectivity for each VM.

The plugin supports configuration caching. The cached configuration is replayed back to the Cumulus Linux switch from the Cumulus ML2 mechanism driver when a switch or process restart is detected.

To deploy OpenStack ML2 in a network with Cumulus Linux switches, you need the following:

  • A REST API, which is installed with Cumulus Linux.
  • The Modular Layer 2 (ML2) mechanism driver for OpenStack, which you install on the OpenStack Neutron controller node. The driver is available as a Python package from upstream.
  • The OpenStack Queens release.

Configure the REST API

  1. Configure the relevant settings in the /etc/restapi.conf file:

    #local_bind =
    #service_node =
    # Add the list of inter switch links that
    # need to have the vlan included on it by default
    # Not needed if doing Hierarchical port binding
    #trunk_interfaces = uplink
  2. Restart the REST API service for the configuration changes to take effect:

    cumulus@switch:~$ sudo systemctl restart restserver

Additional REST API calls have been added to support bridge configuration using the bridge name instead of network ID.

Install and Configure the ML2 Driver

  1. Install the ML2 mechanism driver on your Neutron host, which is available upstream:

    root@neutron:~# git clone https://github.com/CumulusNetworks/networking-cumulus.git
    root@neutron:~# cd networking-cumulus
    root@neutron:~# python setup.py install
    root@neutron:~# neutron-db-manage upgrade head
  2. Configure the host to use the ML2 driver:

    root@neutron:~# openstack-config --set /etc/neutron/plugins/ml2/ml2_conf.ini mechanism_drivers linuxbridge,cumulus
  3. List the Cumulus Linux switches to configure. Edit the /etc/neutron/plugins/ml2/ml2_conf.ini file and add the IP addresses of the Cumulus Linux switches to the switches line. For example:


The ML2 mechanism driver includes the following parameters, which you can configure in the /etc/neutron/plugins/ml2/ml2_conf.ini file.

switchesThe list of Cumulus Linux switches connected to the Neutron host. Specify a list of IP addresses.
schemeThe scheme for the base URL for the ML2 API. For example, HTTP.
protocol_portThe protocol port for the bast URL for the ML2 API. The default value is 8000.
sync_timeA periodic time interval for polling the Cumulus Linux switch. The default value is 30 seconds.
spf_enableEnables and disables SPF for the bridge. The default value is False.
new_bridgeEnables and disables VLAN-aware bridge mode for the bridge configuration. The default value is False, so a traditional mode bridge is created.

OpenStack with Cumulus in the Cloud

OpenStack Neutron is available as a preconfigured option with Cumulus in the Cloud. Add the ML2 driver, described above.