DragonFlow, with Omer Anson from Huawei

OVS Orbit

Omer Anson is a software developer at Huawei. I caught up with him at OpenStack Barcelona back in October to talk about the Dragonflow project, which is a distributed SDN controller for OpenStack Neutron that supports logical switching and routing and more advanced features.

According to Omer, Dragonflow distinguishes itself from other Neutron drivers by aiming at scale. It intends to scale to thousands or even tens of thousands of compute nodes (hypervisors). It also focuses on scale testing, testing in simulation with 4,000 nodes with very good results, showing a slowdown of only about 5% between 30 nodes and 4,000 nodes for control plane operations such as creating subnets or ports.

Dragonflow features include fully distributed DHCP and ARP responders. The latter feature reduces the amount of broadcast traffic within a cloud. Dragonflow can integrate physical devices and even remote clouds into a logical network through its “remote device” functionality.

The Dragonflow implementation currently builds on top of OpenFlow with Nicira extensions (as implemented by Open vSwitch). The developers are also considering adding support for BPF or P4 datapaths.

The Dragonflow design emphasizes pluggability:

My vision is—our vision is—that everything—every Neutron API that exists—will be written as a Dragonflow application. Currently, Dragonflow itself does very little to nothing with creating flows and instructing the policy of how packets move. Everything is done through applications. We have an L2 application which detects the MAC addresses and knows how to direct them to the correct ports, we have an L3 application... that knows to detect when packets are supposed to reach the router and have the layer-2 addresses replaced...

DragonFlow supports, for example, running on top of any of several database systems. The diversity among those databases is vast, which gives users great freedom to choose one that is well suited for their own needs.

Dragonflow has multiple implementations of L3. One of these populates flows proactively into Open vSwitch, that is, it adds flows without waiting for packets to arrive at the controller. The other uses some proactive population along with reactive population, that is, adding flows in response to packet arrival. Omer explains the rationale for the two implementations and how they work.

A new feature of Dragonflow is that it is now implemented as an “ML2 mechanism driver” rather than a Neutron core plugin. This allows it to better coexist with other Neutron drivers within a single deployment.

Omer mentions some upcoming development work, such as a better, more user-oriented deployment mechanism and integration with additional projects such as Ansible, the OpenStack Kolla project, OpenStack Puppet, and more. Service function chaining support is also in the works.

The Dragonflow project is seeking new contributors. You can find the developers in the #openstack-dragonflow channel in the Freenode IRC network. Omer's nick on Freenode is "oanson".

OVS Orbit is produced by Ben Pfaff. The intro music in this episode is Drive, featuring cdk and DarrylJ, copyright 2013, 2016 by Alex. The bumper music is Yeah Ant featuring Wired Ant and Javolenus, copyright 2013 by Speck. The outro music is Space Bazooka featuring Doxen Zsigmond, copyright 2013 by Kirkoid. All content is licensed under a Creative Commons Attribution 3.0 Unported (CC BY 3.0) license.