This document provides an overview of several open source backend alternatives for OpenStack Neutron, including OpenDaylight, Ryu Network OS, and Open Contrail. It summarizes Neutron's built-in solution using ML2 and OVS agents, and how each open source alternative integrates with Neutron. Setup instructions are provided to try each alternative using Devstack.

1. An overview of
Open Source Backends
for Openstack Neutron

2. Summary
● Neutron plugins recap
● Neutron’s built-in solution
● Open source alternatives
○ Open DayLight
○ Ryu Network OS
○ Open Contrail

3. What this talk is NOT about
● Competitive analysis of open source backends
● Telling you which backend would be right for your
deployment
● The holy grail of the infinitely scalable open source
backend

4. What this talk is about
● Enumerating open source alternative for Neutron
backend
● Providing an overview of such backends and how they
integrated with Openstack Neutron
● Proving that Neutron’s “agents” are not the only
alternative to commercial backends

5. Neutron plugins recap
● Modular (ML2) Plugin
○ A common layer for DB management and resource allocation;
transport/technology specific drivers
● Standalone Core Plugin
○ Implementation of one or more interfaces to serve a particular
backend technology or platform
● Both ML2 drivers or standalone plugins can either be
commercial or open-source
● Both commercial and open source plugin/drivers are
required to pass integration testing

6. Neutron’s built-in solution
● L2/L3 connectivity
● IPAM
● East/West routing
● External gateway & floating IPs
● Implemented by:
○ ML2 plugin with OVS agent mech driver
○ OVS Layer-2 agent
○ Layer-3 agent + DHCP agent
● Load Balancing, VPN, and firewall served by distinct
“service plugins”

7. Neutron’s built-in solution
Neutron Server
ML2 with Open
vSwitch
Mechanism
Driver and GRE
transport
ML2
L3 base
plugin
OVS Mech
Driver
AMQP bus
RPC RPC
REST
OVS
Agent
OVS
Agent
OVS
Agent
LB
Agent
L3
Agent
L3
Agent
LB
Agent

8. Neutron’s built-in solution
Installation via devstack
local.conf
○ enable_service neutron q-l3 q-agt q-svc q-dhcp q-meta
./stack.sh

9. Neutron’s built-in solution: limits
Careful messaging needed here.
● Point to scalability limits of the L2 agent
● Point to limit of the L3 agents only if the OSS backends
discussed here have viable alternatives
● Neutron’s developer community is a mix of web app
developers, distributed systems experts and network
programmers.
○ Focus is not exclusively on networking

10. L2Population ML2 Driver
● An overlay MechanismDriver for ML2
○ Optimized by pre-populating forwarding tables of both OVS and
Linuxbridge forwarding planes to decrease broadcast traffic
○ Utilizes both VXLAN and GRE tunnels
● Two main implementation details
○ Local ARP responder on each host
■ Linuxbridge support in Havana, OVS support in Juno
○ Forwarding table population on each host
● More information:
○ https://wiki.openstack.org/wiki/L2population

11. Before
ML2 L2 Population MechanismDriver
Host 1
Host 2
Host 3Host 4
Host 1
VM A
VM G VM E VM D
VM B
VM C
VM F
VM H
VM I
“VM A” wants to talk to “VM G.” “VM A” sends a broadcast
packet, which is replicated to the entire tunnel mesh.

12. With
ML2 L2 Population MechanismDriver
Host 1
Host 2
Host 3Host 4
Host 1
VM A
VM G VM E VM D
VM B
VM C
VM F
VM H
VM I
The ARP request from “VM A” for “VM G” is intercepted and
answered using a pre-populated neighbor entry.
Proxy Arp
Traffic from “VM A” to “VM G” is
encapsulated and sent to “Host 4”
according to the bridge forwarding table
entry.

13. Try L2Population with devstack
● Setup your local.conf to use L2Population with LB
Q_PLUGIN=ml2
Q_AGENT=linuxbridge
Q_SERVICE_PLUGIN_CLASSES=neutron.services.l3_router.l3_router_plugin.L3RouterPlugin
Q_ML2_PLUGIN_MECHANISM_DRIVERS=openvswitch,linuxbridge,l2population
Q_ML2_TENANT_NETWORK_TYPE=vxlan,gre
...
[[post-config|/$Q_PLUGIN_CONF_FILE]]
[vxlan]
enable_vxlan=true
local_ip=$HOST_IP
l2_population=True
● More information (including OVS setup with L2Population)
○ https://wiki.openstack.org/wiki/L2population

14. OpenContrail
● OpenContrail is an extensible networking system
covering two primary use cases:
○ Cloud Networking
○ Network Function Virtualization
● Consists of two components:
○ OpenContrail Controller
■ Configuration, Control, and Analytics nodes
○ OpenContrail vRouter
● http://opencontrail.org/

15. Open Contrail:
Openstack integration
● VM bringup with OpenContrail:
○ Nova instructs the Nova Agent on the compute node to create the VM
○ Nova Agent gets network attributes from OpenContrail Plugin
○ Once VM is created, Nova Agent communicates to vRouter
○ vRouter configures the virtual network for the VM

16. Neutron with Open Contrail diagram
OpenStack
Nova Contrail
Neutron
Plugin
Compute Node
OpenStack Nova
Agent
vRouter
Agent (user
space)
Configuration Node
Contrail Node

17. Try OpenContrail with devstack
● Pull the devstack with OpenContrail support
○ git clone https://github.com/dsetia/devstack
● Setup your local.conf
○ ENABLE_CONTRAIL=yes
○ Q_PLUGIN=contrail
○ PHYSICAL_INTERFACE=eth0
● This will enable a single node OpenContrail setup
with devstack
● For more information:
○ http://pedrormarques.wordpress.com/2013/11/14/using-
devstack-plus-opencontrail/

18. OpenDaylight
● OpenDaylight is an Open Source Software Project under the Linux
Foundation with the goal of furthering the adoption of SDN
○ Three pillars: Code, Acceptance, and Community
● OpenDaylight is building an evolvable SDN platform capable of handling a
diverse set of use cases
○ IaaS network orchestration is an important use case
● Releases:
○ Hydrogen: February 2014
○ Helium: Tentatively slated for September 2014
○ Three release types:
■ Base, Virtualization, and Service Provider
● Eclipse Public License – v 1.0 (EPL)
● http://www.opendaylight.org/

19. Open DayLight
Openstack integration
● OpenStack Neutron ML2 MechanismDriver upstreamed
in Icehouse
● REST proxy, passes API calls into OpenDaylight
● Utilized by any provider’s southbound in ODL
○ Examples: VTN, OVSDB Plugin, OpenDove
● Solution still requires Neutron DHCP and L3 agents
○ Support for this planned for Helium release

20. Neutron with
Open DayLight diagram
Neutron Node
Neutron Server
ML2 Plugin w/
ODL Driver
Network Node
L3 Agent
OVS
DHCP
Agent
Compute Node
OVS
OpenDaylight Node
ODL Server
REST API
RPCs
OpenFlow
and OVSDB
Neutron
API
Service
OVSDB
Plugin

21. Try OpenDaylight With devstack
● Setup your local.conf
○ Q_ML2_PLUGIN_MECHANISM_DRIVERS=opendaylight
○ enable_service odl-server odl-compute
● This will enable a single-node OpenDaylight devstack
setup
○ Additional compute nodes only need “enable_service odl-compute” set
● Checkout lib/opendaylight for more configuration
options

22. Ryu Network OS
● Ryu is a component-based SDN framework
○ Supports OpenFlow 1.0, 1.2, 1.3, 1.4, and Nicira extensions
○ Apache 2.0 license
○ Written in Python
● Supports a variety of protocols for managing network
devices
○ OpenFlow, Netconf, OF-config, SNMP
● http://osrg.github.io/ryu/

23. Ryu Openstack integration
● Ryu is integrated into OpenStack in two ways:
○ A standalone plugin
○ An ML2 MechanismDriver (ofagent)
● Multi tenant network support
○ Mac address based
○ VLAN
○ GRE tunnel
● Ryu supports port-binding
○ Ryu agent or ofagent must be running on the host
●

24. Neutron with Ryu diagram
Neutron Node
Neutron DB
(network ID, key)
Neutron Server
RYU Plugin
Ryu Node
Ryu Server
Network Node
L3 Agent
Ryu
Agent
Compute Node
Ryu
Agent OVS
OVS

25. Try Ryu with devstack
● Setup your local.conf
○ Q_ML2_PLUGIN_MECHANISM_DRIVERS=ofagent,l2population
○ Q_AGENT=ofagent
○ ENABLE_TENANT_TUNNELS=True
○ Q_ML2_TENANT_NETWORK_TYPE=gre
○ [[post-config|/etc/neutron/plugins/ml2/ml2_conf.ini]]
○ [agent]
○ l2_population=True
● This enables a single-node ofagent setup with
Ryu
● More information:
○ https://github.com/osrg/ryu/wiki/OFAgent-Openstack-
IceHouse-environment-HOWTO

26. Summary
● Many options in the Open Source Arena for
Neutron Plugins
○ Innovation is ongoing in this area
● No “one size fits all”