Open Source Enables Scale-out in SDN Powered Microsoft Azure


Microsoft Azure’s programmable, scalable and high-performance network infrastructure is leveraging software-defined networking (SDN) principles as well as open source components to meet the demands of massive cloud-based production environments, said Albert Greenberg, Director of Azure Networking and Distinguished Engineer at Microsoft, at Open Networking Summit 2016.

A major part of Greenberg’s talk was on servicing – updating software in an agile way, fixing bugs, releasing updates, for a production environment of over a million servers.

First, he provided context for the Azure network infrastructure evolution over the last three years:

  • He summarized what is going on in the v-switch running in the hypervisor and controller, how SDN complex policies in the host are realized and where a server gets smarter about policy, and the network feature set now known as network functions virtualization.

  • He described how Express Route allows customers to connect enterprise datacenters to the cloud and enables real-time scalability –something that can’t be bought with a router. Eg: 100 million routes can be enabled by express route by hot attaching Azure and deploying as if Azure is part of the network.

  • He shared how Microsoft builds its scalable controller using a Microsoft  open platform called service fabric and how SmartNIC hardware allowed offloading host policy into hardware.

Then he introduced the Virtual Filtering Platform (VFP), Azure’s programmable dataplane, in which the company has  scaled up the match action table model to support modern high density servers with >40Gbps of bandwidth, while providing the programmability for its many controllers and SDN applications to create new virtual networking functions.

And finally, he discussed innovations in the data plane, control plane, and physical network in Microsoft Azure network infrastructure.

Data Plane

Packet Direct is the new Windows direct I/O model for accelerating virtual networking and NFV Optimized VFP which offers up to 2x improvement in throughput for heavy VNET workloads, up to 4x PPS improvement in E2E and is supported on major NICs.

Control Plane

Containers play a major role in scaling the private cloud by getting more from VMs. This offers fast provisioning, scalability for  hundreds of thousands  of containers in the virtual networks, and seamless DevOps for containers. This is accomplished with underlay container management with namespace and VM policies in the VFP so containers can be addressable over the network.

Physical Network

Greenberg introduced Software for Open Networking in the Cloud (SONiC), an open source full routing stack which allows running software on a physical network as a collection of software networking components enabling network devices like switches with rich functionality. SONic enables feature agility, hitless upgrades and restarts with zero customer impact. It runs on top of different switching platforms via the Switch Abstraction Interface (SAI).

SAI is the software abstraction interface that enables logical separation between hardware and software to accommodate a variety of ASICS and enables innovation in both independently.

SONiC lays on top of SAI to unify software running on top of different switches into a cloud-wide network management platform.

He went on the demonstrate how SONiC enables feature agility, hitless upgrades and restarts with zero customer impact.

Watch the full talk, ‘Scaling the S in SDN,’ below.


Watch past Microsoft Talks as follows:

2015: ‘SDN in a Hyperscale Cloud’ by Mark Russinovich, CTO, Microsoft Azure

2014: Scaling SDN in the Public Cloud’ by Albert Greenberg, Director of Development, Windows Azure Networking, Microsoft