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Why SDN is just the first step towards business agility

by Citrix
February 2016
ADC | SDN
SDN 102: Software Defined Networks and the Role of Application Delivery Network Services

Citrix Whitepaper: SDN and the Role of Application Delivery Network Services Download

The extra speed and flexibility of the cloud computing model has raised enterprise expectations. So IT teams must find a way to respond. But while much of the attention has been paid to the way software-defined networking (SDN) can help with network infrastructure, other application considerations have been left lagging behind.

It is important to recognise that SDN itself is not the end game. Delivering IT resources on-demand and in the most efficient manner are where enterprises will see the biggest gains in business agility, productivity and user satisfaction. This can be done through application automation.

But an application is more than just the elements you install on a server. They rely on many different components to work smoothly. The network remains integral to the success of an application and should always be a key consideration in any automation programme.

SDN is the first step on that journey.

In the last few years, software-defined networking (SDN) has matured to help deliver applications more effectively. Previously, the focus had been on L2-L3 switching and routing services. These only covered the network connections. The IT sector is getting smarter and seeing that the real value lies in stepping up automation beyond the network to the application layer as well. Now, SDN has evolved to address the L4-L7 application requirements too, covering availability, performance, security and visibility.

But there is no single model for implementing SDN.

So what do enterprises need to consider before moving forward with SDN?

Firstly, it is good to know where some of the thinking originates. The Open Networking Forum (ONF) was a pioneer of the standardisation of SDN. Its OpenFlow standard is based on decoupling the network, making it directly programmable. The OpenDaylight Consortium takes a more pragmatic approach. Its model for complex projects like SDN is to prove the concept first before setting any standards.

Opendaylight consortium model

Secondly, there is the difference between network virtualisation models:

  • Overlay-based model: This is based on tunnelling and encapsulation. It is agnostic to the underlying IP network and can be implemented without changes to that network.

Orchestration platform

  • Fabric-based model: This closely resembles the ONF vision for SDN. Unlike the overlay model, a key advantage is that there is a single network to manage. Monitoring and visibility of traffic is easier too.

The issue is that these all do the same thing. They simply reconfigure the network to adapt to change.

Cisco’s Application Centric Infrastructure (ACI) takes a different approach. ACI establishes the application as the most important element in the new enterprise IT paradigm. It separates the network design from the physical infrastructure. In turn, this allows IT teams to specify application needs as policies.

With ACI, virtualising the network is a necessary benefit. But virtualising and calling on the network services required to deploy and deliver networks is a game changer.

Yet Cisco understands that they cannot achieve all of this alone. They have called upon technology partners, like Citrix, to help businesses achieve the benefits at the application layer. Citrix and Cisco have worked together on a number of joint projects over the years. Perhaps the most crucial one has been the introduction of Citrix NetScaler as the Application Delivery Controller (ADC) of choice for Cisco – replacing the previous generation of Cisco ACE load balancers.

NetScaler has become the beacon technology for Cisco ACI and is the device that enterprises can rely on to achieve the levels of business agility not possible through SDN alone.

SDN 102: Software Defined Networks and the Role of Application Delivery Network Services

Citrix Whitepaper: SDN and the Role of Application Delivery Network Services Download

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