OpenFlow Advances Networking and Test Requirements

Cloud computing and virtualization are expanding demands on the data center and are pushing the limits of scalability in network switching. The need for any-to-any connectivity is forcing network designers and equipment manufacturers beyond the traditional hierarchical model of switch ports to the full-mesh approach of switch fabrics. And as usual, the expectation of reduced time to market and deployment continues to accelerate.

Enter software-defined networking (SDN), which fosters greater flexibility and extensibility in network switching through open interfaces and increases predictability in network control by separating the control plane from the data plane.

OpenFlow, a protocol initially developed at Stanford and now managed by the Open Networking Foundation (ONF), is based on the SDN concept and uses two primary components, a controller and a switch, which communicate via a standard open programming interface.

In March, 2012 the ONF Testing-Interop working group planned and managed an event to validate the interoperability of member ONF 1.0 implementations. Spirent Communications joined the ONF in its founding year and participated in the event.

Tests included:

  • Network discovery using link layer discovery protocol (LLDP)
  • Layer 2 circuit provisioning
  • Layer 3 (IP) learning with dynamic provisioning and failover
  • Load balancing
  • L2 MAC learning
  • Slicing the network with FlowVisor

An interoperability event with a dozen vendors poses a host of logistical and technical challenges. Spirent Communications helped participants in interoperability trials by troubleshooting connectivity with flow analysis, decoding discovery frames, traffic generation, validating data paths, and measuring failover convergence times.

Test realism is a critical component of any effective test methodology that validates performance, availability, security and scalability.

As OpenFlow matures, it must support multiple tenants within and across multiple data centers simultaneously, while properly separating and securing traffic in a highly automated environment and handling load scheduling and balancing of additional users, VMs and services.

Future testing will move beyond interoperability to flow capacity testing at high port density in native OpenFlow and hybrid networks, which will become increasingly important to validate real-world performance against the expectations of the always-on, always-connected users in the twenty-first century.

This in-depth white paper from Network Test covers 10 test sets that should be a mandatory part of any comprehensive evaluation of data center switching. It also describes the less-than-ideal practices that should be avoided.

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