Hybrid SDN: Managing the Physical and Virtual in Parallel

According to a recent Infonetics survey, virtually all major operators globally are either currently looking into SDN or will do so within the next three years, and 86 percent of the operators surveyed plan to deploy SDN technology once standards are final. SDN adoption is still at an early stage and a lot of operators are waiting to see how early adopters fare before making any major investments in network upgrades. Nevertheless, major service providers worldwide including Deutsche Telekom, Telefonica, Telus and Telstra have either announced SDN deployments or are currently undergoing pilots.

Suffice to say, the paradigm has undeniably shifted from if operators should move forward with SDN, to when and how. As with all new technologies, there’s always a first step to take and its associated obstacles. That first step will be taken cautiously without vast amounts of equipment being ripped out. Infonetics’ Michael Howard refers to these limited SDN deployments being in “contained domains.” By restricting deployments to limited areas of their networks, operators can focus on where they can generate new services and therefore, new revenue, before network-wide implementation. Ultimately, deployments in contained domains will ensure that the technology works as it is intended to, so that operators understand where they can maximize value when deploying SDN in broader areas of the network.

For the time being, operators will inevitably have to manage a hybrid system as they embrace and migrate to virtualized network architectures and allow traditionally configured networks to provide SDN features within the same environment. In order to do this, network administrators can partition a switch so that specific types of traffic can be forwarded using legacy Ethernet technologies and the rest of the traffic to be forwarded based on rules programmed using standards such as OpenFlow. Expanding traditional network technologies through this method empowers network operators to have greater control over standard networking control plane features.

Although this hybrid method does not provide centralized routing decision-making and therefore must gather considerable amounts of network and status performance information across all protocol layers, device types, and vendors involved, it provides control plane flexibility without having to overhaul the entire network system. By introducing OpenFlow to legacy network environments, network operators can gradually familiarize themselves with SDN deployments in a controlled setting and gain a better understanding of the migratory process, mitigate risks, and comprehend the technology in order to properly scale the solution when the time is right.

To help facilitate the adoption of a hybrid network, the Open Networking Foundation recently announced the latest OpenFlow Switch Specification (v 1.3.2, April 2013), which includes specifications for hybrid interactions between OpenFlow and traditional Ethernet switching technology. At the same time, companies such as Aricent are leveraging their SDN software frameworks and domain expertise in order to help network equipment vendors add support to their switches and routers to enable them to run in hybrid mode. The culmination of industry support creates a perfect market for operators to move forward with their SDN initiatives.

Hardware lifecycles are quickly becoming shorter as technology and service innovation accelerates, potentially inhibiting the roll-out of new revenue-earning network services and constraining innovation in an increasingly network-centric world. This alone should be rationale enough for encouraging international collaboration to accelerate the standardized development and deployment of interoperable SDN technologies.

With the promise of greater network flexibility, planning, uptime, and better management, as well as OPEX and infrastructure savings, software-defined networking is hailed by some in the industry as the “holy grail” of networking. But we need to take it one step at a time – and that first step is creating a hybrid system. Within the next few years, network operators will inevitably become involved with SDN to some degree. As the technology is now on a slow and steady growth curve, starting with a hybrid approach in order to understand how the technology can benefit organizations with agility and flexibility will ultimately prepare network operators with the knowledge and experience for broader SDN deployments once standards are final.

This article was originally published in SDN Zone.

Leave a Reply

Your email address will not be published. Required fields are marked *