Easing Complexity on the SDN Controller

Software-defined networking (SDN) is bringing a great deal of flexibility to the enterprise network, but it also adds a fair amount of complexity to what many now consider its single point of failure: the controller.

In theory, much of this complexity will be masked under layers of automation, allowing both users and managers to provide seamless connectivity across disparate data environments. But this doesn’t hide the fact that if something were to go wrong with SDN, it will probably happen on the controller. And that could have a cascading affect for the entire data chain.

Most work on the SDN controller these days centers on improving its functionality and extending its reach over distributed fabric architectures. Cisco recently added a cloud-based plug-and-play (PnP) feature to its APIC-EM controller that enables automated connectivity for a wide range of network devices. Product manager Shahrukh Raheem says the intent is to simplify the zero-day provisioning process for routers, switches and wireless access points by eliminating tasks like pre-staging and reducing the chance of manual configuration errors. PnP Connect basically acts like a discovery mechanism that offloads configuration provisioning tasks from the controller so that devices can automatically populate within the service’s cloud portal.

Meanwhile, Huawei and Ubuntu developer Canonical have teamed up to integrate their respective data fabric and OpenStack solutions. The partnership has Huawei supporting the Canonical Ubuntu OpenStack distribution on the Agile SDN controller, which should allow network operators to deploy and manage large numbers of controller nodes on either data center- or cloud-based networks. The agreement also allows Canonical’s Juju service modeling tool to work with the Agile controller, providing a means to deploy OpenStack workloads quickly in conjunction with multiple third-party SDN controllers without extensive manual configuration. The partnership is part of Huawei’s effort to establish an all-cloud network management environment.

Other vendors, however, are looking at SDN controller complexity and deciding it would be better to eliminate it altogether. Pluribus Networks’ new Adaptive Cloud Fabric (ACF) does away with the centralized control plane seen in current SDN implementations in favor of a distributed, peer-to-peer approach that pushes controller logic to open switches. In this way, the company says the enterprise can build a dynamic, secure networking ecosystem that is more in line with rapid configuration and customization needs of digital service-based operating models. The system maintains connectivity using standard L2/L3 protocols and features high levels of automation, programmability and end-to-end visibility that are required of emerging software defined data center (SDDC) architectures.

Sunay Tripathi, Pluribus co-founder and CTO, says that the ACF, powered by the company’s Netvisor operating system, more closely mirrors server virtualization architectures in the data centerin that it distributes fabric intelligence across virtual switches. This in turn allows a single network device to support multiple network containers with individualized routing capabilities for highly granular network segmentation and isolated multi-tenant services. Without having to run all this logic through a central controller, the platform enables organizations to push virtual data environments to cloud-scale proportions using standard commodity hardware and virtual extensible LAN (VXLAN) tunneling solutions.

It was almost inevitable that as SDN matured it would start to produce increasingly divergent deployment options. And more than likely, there will prove to be no right or wrong way to do SDN in the future, with each version providing optimal support for some workloads but not others.

But as a rule, SDN will enable more flexible, scalable and extensible network environments than most enterprises enjoy today — and at less cost and with less management overhead.

Arthur Cole is a freelance journalist with more than 25 years’ experience covering enterprise IT, telecommunications and other high-tech industries.

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