OpenStack Summit November 2013

Over the past year, VXLAN has emerged as a leading technology for deploying highly scalable clouds on top of a layer 3 fabric. In this talk, we'll dive into the requirements and benefits of a VXLAN based design, the options for deploying OpenStack on top of a VXLAN fabric today, and the current limitations of VXLAN support and the future work required within OpenStack and Neutron to make VXLAN more widely deployable. We'll also talk about the work that Arista Networks has done within the Modular L2 Neutron plugin to integrate the management of the physical network into OpenStack and provide a solution that automates the provisioning of logical tenant networks across both the virtual and physical network.

Why VXLAN?
VLANs are simply no longer sufficient for modern, multi-tenant clouds. VXLAN is a standardized overlay technology for encapsulating layer 2 traffic on top of an IP fabric, resulting in a more scalable and fault tolerant network design that can support a much larger number of tenant networks than a standard VLAN-based design. Arista has been a leading proponent of VXLAN, having been an author of the original VXLAN spec and having shipped the industry's first physical switch with VXLAN support.

Solution Requirements
Besides the obvious requirement of a virtual or physical switch that serves as the VXLAN tunnel endpoint (VTEP), there are a couple other key requirements to consider in deploying OpenStack clouds on top of VXLAN:

1/ while the VXLAN spec specifies the use of IP multicast to distribute broadcast, unknown unicast, and multicast traffic, most people do not want to deploy IP multicast and therefore require an alternative solution for learning and flooding

2/ for physical workloads that are not VXLAN-aware (for example storage or non-virtualized servers), or for the gateway for North-South traffic into and out of your OpenStack cloud, you need the ability to bridge traffic into and out of the VXLAN fabric at a high bandwith that a software gateways cannot generally provide.

Running OpenStack on top of a VXLAN fabric
OpenStack and Neutron provide a range of options for deploying your cloud on top of VXLAN. You can build on top of native Neutron components, or leverage an external SDN controller. You also have to the choice of where your VTEP functionality resides, whether it's in the virtual switch, the physical switch, or a mix of both. We'll go over these various options for deploying OpenStack using VXLAN, their current advantages and limitations, and the work that Arista has done to integrate the provisioning and orchestration of the physical network into these solutions. We'll also talk about the future work required in Neutron to continue to expand the options for deploying OpenStack over a VXLAN fabric.