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Revision as of 16:23, 12 September 2013 by Mark T. Voelker (talk | contribs)

A Cisco Plugin Framework for Neutron L2 Network Overlays Spanning Multiple Physical Switches (Havana Release)


This plugin implementation provides the following capabilities:

  • A reference implementation for a Neutron Plugin Framework (For details see: http://wiki.openstack.org/quantum-multi-switch-plugin)
  • Supports multiple switches in the network
  • Supports multiple models of switches concurrently
  • Supports use of multiple L2 technologies
  • Supports the Cisco Nexus family of switches (Verified with Nexus 3000, 5000 and 7000 series)

Overlay Architecture

The Cisco plugin overlay architecture uses model layers to overlay the Nexus plugin on top of the Openvswitch plugin. It supports two segmentation methods for the Openvswitch plugin: VLAN and GRE tunnels.


(The following are necessary only when using the Nexus devices in your system. If you plan to just leverage the plugin framework, you do not need these.)

If you are using a Nexus switch in your topology, you'll need the following NX-OS version and packages to enable Nexus support:

  • NX-OS 5.2.1 (Delhi) Build 69 or above.
  • paramiko library - SSHv2 protocol library for python
  • ncclient v0.3.1 - Python library for NETCONF clients
    • You need a version of ncclient modified by Cisco Systems. To get it, from your shell prompt do:
git clone git@github.com:CiscoSystems/ncclient.git
sudo python ./setup.py install
  • For more information of ncclient, see: http://schmizz.net/ncclient/
  • OS supported:
  • RHEL 6.1 or above
  • Ubuntu 11.10 or above
  • Package: python-configobj-4.6.0-3.el6.noarch (or newer)
  • Package: python-routes-1.12.3-2.el6.noarch (or newer)
  • Package: pip install mysql-python

Module Structure

  • neutron/plugins/cisco/ - Contains the Network Plugin Framework
    • /client - CLI module for core and extensions API
    • /common - Modules common to the entire plugin
    • /conf - All configuration files
    • /db - Persistence framework
    • /models - Class(es) which tie the logical abstractions to the physical topology
    • /nexus - Nexus-specific modules
    • /test/nexus - A fake Nexus driver for testing the plugin

Basic Plugin Configuration

1. Make a backup copy of /etc/neutron/neutron.conf

2. Edit /etc/neutron.conf and edit the "core_plugin" for v2 API. Also verify/add keystone information.

core_plugin = neutron.plugins.cisco.network_plugin.PluginV2

auth_host = <authorization host's IP address>
auth_port = 35357
auth_protocol = http
admin_tenant_name = service
admin_user = <keystone admin name>
admin_password = <keystone admin password>

3. MySQL database setup:

  • 3a. Create neutron_l2network database in mysql with the following command -
mysql -u<mysqlusername> -p<mysqlpassword> -e "create database neutron_l2network"
  • 3b. Enter the neutron_l2network database configuration info in the [DATABASE] section of the /etc/neutron/plugins/cisco/cisco_plugins.ini file.

4. Configure the model layer to use Openvswitch as the vswitch plugin:

  • Update the "vswitch_plugin" value of the [CISCO_PLUGINS] section of /etc/neutron/plugins/cisco/cisco_plugins.ini:

Cisco Plugin Overlay in Openvswitch GRE Tunnel Mode

In this mode the Nexus switch doesn't configure anything and acts as a simple passthrough.

  • Configure the OVS plugin with the following settings in /etc/neutron/plugins/openvswitch/ovs_neutron_plugin.ini:
tenant_network_type = gre
enable_tunneling = True
tunnel_id_ranges = 1:1000
local_ip =

  • Modify the [CISCO] section of the /etc/neutron/plugins/cisco/cisco_plugins.ini to add model class and the fake nexus driver:

Cisco Plugin Overlay in Openvswitch VLAN Mode

  • Configure the OVS plugin with the following settings in /etc/neutron/plugins/openvswitch/ovs_neutron_plugin.ini:
bridge_mappings = physnet1:br-eth1
network_vlan_ranges = physnet1:1000:1100
tenant_network_type = vlan

  • Configure the [CISCO_PLUGINS] of /etc/neutron/plugins/cisco/cisco_plugins.ini:

  • Configure the Nexus switch information in /etc/neutron/plugins/cisco/cisco_plugins.ini. The format should include the IP address of the switch, a host that's connected to the switch and the port on the switch that host is connected to. Also, add the Nexus switch credential username and password. You can configure multiple switches as well as multiple hosts per switch as shown in the example below:
# Hostname and port used of the node
# Hostname and port used of the node
# Port number where the SSH will be running at the Nexus Switch, e.g.: 22 (Default)
# Provide the Nexus credentials, if you are using Nexus switches. If not this will be ignored.

# Hostname and port used of the node
# Hostname and port used of the node
# Port number where the SSH will be running at the Nexus Switch, e.g.: 22 (Default)
# Provide the Nexus credentials, if you are using Nexus switches. If not this will be ignored.

  • Make sure that SSH host key of all Nexus switches is known to the host on which you are running the Neutron service. You can do this simply by logging in to your Neutron host as the user that Neutron runs as and SSHing to the switches at least once. If the host key changes (e.g. due to replacement of the supervisor or clearing of the SSH config on the switch), you may need to repeat this step and remove the old hostkeys from ~/.ssh/known_hosts.
  • In general, make sure that every Nexus switch used in your system, has a credential entry in the above file. This is required for the system to be able to communicate with those switches.
  • Start the Neutron service. If something doesn't work, verify the configuration of each of the above files.

How to Test the Installation

The unit tests are located at neutron/tests/unit/cisco/. They can be executed from the top level Neutron directory using tox (
[sudo] pip install pip testrepository

1. Testing the core API (without UCS/Nexus/RHEL device sub-plugins configured):

  • By default all the device sub-plugins are disabled (commented out) in etc/neutron/plugins/cisco/cisco_plugins.ini
   tox -e py27 -- neutron.tests.unit.cisco.test_network_plugin
   tox -e py27 -- neutron.tests.unit.cisco.test_nexus_plugin

2. For testing the Nexus device sub-plugin perform the following configuration:

  • Edit etc/neutron/plugins/cisco/cisco_plugins.ini to add: In the [CISCO_PLUGINS] section add:
  • Edit the etc/neutron/plugins/cisco/cisco_plugins.ini file. When not using Nexus hardware use the following dummy configuration verbatim:
# Hostname and port used of the node
# Port number where the SSH will be running at the Nexus Switch, e.g.: 22 (Default)


Older Releases

Information for Grizzly and older releases can be found here: