How data center network fabric and SDN intersect

SDN and data center network fabrics both enable converged networking and the ability to manage many switches as one. Where do the two intersect?

What is the relationship between data center network fabric and software-defined networking? The question will...

become increasingly relevant as engineers begin using SDN and network fabrics for scalability and manageability in high performance data centers. But vendors will offer divergent strategies in which SDN and network fabrics are either totally interdependent or largely independent of each other. Users will have to determine which strategy works for them.

SDN and network fabrics: Similar roles in the data center?

Network fabrics are defined as high-performance, low-latency, scalable Ethernet switching products that connect compute, storage and software elements in a converged network. The goal is to enable any-to-any connectivity between nodes on the network and to allow multiple switches to be managed as one.

SDN, on the other hand, provides a software abstraction of the physical network that allows the network to be programmable and specifically tied to the needs of applications. However, this software abstraction can be used in the data center to take on centralized management of multiple components, similar to network fabrics.

Now, many vendors are architecting their next-generation data center networks around both high-performance network fabrics and SDN architectures.

For most data center network applications, the underlying physical network will work in conjunction with SDN protocols to deliver a scalable, high-performance, low-latency network. So, the question becomes this: How tightly integrated will SDN technologies and network fabrics become in the future?

Three SDN and data center network fabric strategies

In one camp, the SDN architecture and network fabric technology would be purchased from separate vendors and would operate independently with some interaction. For example, the SDN software abstract could control the physical Ethernet fabric. Proponents believe using technologies that are independent of each other provides an easy-to-deploy, flexible solution that can leverage any physical network infrastructure.

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At the other end of the spectrum, SDN would be fully integrated with the physical network fabric, with both being provided as a joint product or architecture from the same vendor. Suppliers offering this model include incumbents, such as Cisco, Juniper and SDN startup Plexxi. The advantages of this model include the ability to offer application programming interfaces that directly link applications to the network fabric, thus improving Quality of Service and reducing latency. Integrated SDN protocols make the network fabric more application-aware and facilitate Quality of Service for specific applications.

In between the two extremes, suppliers such as IBM, Dell, NEC and HP will offer data center networking solutions where SDN software is linked to, but not dependent on, the underlying network fabric.

In this scenario, hyperscale data centers will continue to rely on Ethernet switching and routing, including network fabrics, to deliver high-performance, converged data center networking. Within this, SDN technologies will be adopted to facilitate VM provisioning, support Multi-tenancy and improve application performance.

As network fabrics and SDN are deployed in the data center, their functionality will overlap and in some cases merge. Ultimately, the marketplace will decide the benefits or drawbacks of integrating SDN into the physical network infrastructure.

About the author
Lee Doyle is a principal analyst at Doyle Research. Doyle Research delivers quantitative and qualitative analysis, forecasting and market-positioning advice to network and IT industry professionals.

This was last published in March 2013

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