The Era of Networking Datapath Flexibility

By Sujal Das | Apr 11, 2016

With the brunt of networking tasks moving to servers, thanks to the tremendous benefits that SDN and NFV brings to users, the need for networking datapath flexibility has quickly come to the forefront. This is not the first time, though. In the past, networking datapath flexibility-related use cases and success criteria have been associated with supplementing features available in fixed function networking ASICs or vendor differentiation. In the new era, use cases and success criteria relate to more compelling and widespread needs: data center infrastructure scaling with efficiency, and speed of innovation.

Let’s take a brief look at the history. ASICs that implement fixed networking datapaths have existed since the beginning of networking and have thrived over time. NIC and Switch ASICs have done well in networking applications because by being fixed function, they bring the inherent benefits of lower cost and power, and shorter time to market. The use of NPUs and FPGAs has enabled datapath design flexibility and has found use and success complementing or replacing ASICs in campus and data center edge applications (close to the WAN) where the bandwidth requirements as well as cost and power constraints are lower and flexibility is more valuable. Vendors would implement their own proprietary datapath requirements in the NPU or FPGA when an ASIC option that supported such datapath applications was not available. When ASICs evolved to support such functions, the use of NPU or FPGA could be discontinued to save costs. As such, applications that required networking datapath flexibility never reached mainstream status.

Modern data centers that scale most efficiently are built using SDN and NFV technologies. The fundamental tenet of such technologies is about simplifying the network switching infrastructure and moving the intelligence to compute servers. When sophisticated networking functions are implemented in the servers, using a software based approach for functions like virtual switching Linux firewall, data center operators enjoy multiple efficiency benefits – speed of innovation, cheaper and more scalable network switching infrastructure and distributed scaling. For example, with this approach, security policies can be deployed closer to the applications and tenant VMs or containers, enabling significant efficiency in the handling of growing east-west traffic patterns in modern data centers.

Several server-based networking datapaths have evolved in the software world, each of them open. Examples include the flexible datapaths implemented using the Open vSwitch (OVS), the Linux Firewall, Open vSwitch for Networking (OVN), Contrail vRouter, the Metaswitch Calico project, PlumGrid IO Visor, and most recently FD.IO from the Linux Foundation. As bandwidth requirements in servers have increased, such server-based networking, when implemented purely in software, is becoming prohibitively expensive – too many x86 server CPU cores are consumed performing networking tasks at suboptimal performance. As such, there is now a resurgence in the world of hardware: SmartNICs that can implement flexible networking datapaths returning those CPU cycles that were consumed with networking and security tasks to service applications (VNFs).

SmartNICs designed for COTS servers – such as Netronome’s Agilio Server Networking Platform – effectively serve the new era of networking datapath flexibility. They bring the best of both worlds to address mainstream data center SDN and NFV applications: the speed of software innovation is united with the performance and efficiency of hardware. The result is increased agility of new feature rollouts and significantly improved server efficiency by enabling more applications, VMs or containers per server while increasing throughput. These benefits in the new era of networking datapath flexibility are hallmarks of high volume and mainstream deployments.