Exploring the value of the software defined data centre

THE CLOUD IS STILL ESSENTIALLY A ROOM FULL OF SERVERS, switches and cables which provides IT resources via a connection whether that be a private one or the internet. However customers’ expectation of the cloud far outweighs the reality because essentially they think their servers are all sitting together in a private environment. In the real world they can be dispersed through racks and even different data centres. By using a Software Defined Network to bring them all together automatically we can provide truly burstable cloud services and finally bring the reality of the provision in line with expectation.

At its simplest level Software Defined Networking (SDN) is about removing the physical switches and routers from the process of firing up servers. At the more complex level SDN introduces an abstraction layer separates the network intelligence and configuration from the physical connections and hardware. Instead of provisioning a customer’s services by physically changing switches and routers, SDN allows you to do this via one simple touch point on the control pane. If a customer wants more servers but you can’t rack them in the same location, you can provision them to be connected via the software in a different location. Physically you don’t have to plug anything in.

As we all know the data centre environment is a challenge when it comes to design and legacy networks have serious limitations. You can’t easily rip it up and start again to quote a 1980s pop song. Changes and upgrades are very expensive and you don’t want to be doing them too frequently.
Traditionally networks have been constrictive because of the way the network topology works. Adding servers and service on to existing and new network segments is a complex task requiring accessing multiple systems directly. This increases risk as well as complexity. Using Software Defined Network technology removes that barrier.

Traditional networks have worked to a 4096 Vlan Limit and used a Spanning Tree configuration to avoid loops being formed when switches or bridges are interconnected via multiple paths. Other problems have been the difficulty in scaling hosting requirements quickly, having to keep services together in one geographic location and the difficulties in upgrading capacity from 10Gb through 40 Gb and up to 100Gb.

By using SDN you create a more scalable and flexible network and at the same time reduce complexity and administration. There are significant benefits around greater speed of deployment and provisioning. It does not matter where a customer’s servers are located - they don’t need to be in the same rack or data hall to be connected. Everything is done at the network layer.
Using SDN in combination with a spine-leaf class multi-root network topology enables huge scalability within the data centre. For instance our Vlan Limit is now 50,000, we can host scale to 300,000 virtual servers, there’s no spanning tree in the core, we can provide any service in any rack through a single point of programming.
Once implemented future upgrades are far less disruptive because you’re updating software not updating physical hardware in the data centre. Having a Software Defined Network means it is simpler to manage the data centre environment. Instead of the old fashioned way of racking ‘tin’ the provision of services is all done by the command software.
Business is definitely diving deep into the adoption stage for Cloud services. The demand now is for the agility to access applications, infrastructure, and other IT resources on demand but this has to be done in an environment of increased security, compliance, and auditing requirements.

Providing self-service provisioning, whether in a private or public cloud, requires elastic scaling of computing, storage, and network resources, ideally from a common viewpoint and with a common suite of tools. The addition of SDN paves the way for the next generation of Cloud systems.
In a sense what matters for the enterprise is that the Cloud works rather than how it works. It’s important that the enterprise has the CPU, disks, RAM etc to deliver on its compute strategy but when it comes to the technology and the platform that underpins it this should be left to the hosting providers who are the experts because Software Defined Network technology is expensive and complex.

What is more important for the enterprise is the issue of security in the cloud. What we need to ensure is that there is a seamless link from the enterprise to the data centre. The challenge is to get to the point where the office network is the same as the data centre network and everything just works. Investing in SDN technology is just the start of us getting rid of the ugly connections that exist today. The main development will be around additional functionality and flexibility within the data centre.
What we are working on is being able to carry out data centre to data centre workload migrations without changing IP addresses or routing. The aim is for us to be able to have active-active SAN Storage where you’re running a virtual machine and can move it live without dropping traffic.

The customer might not know any different but you and your data centre management team will and that’s the empowering proposition for this new technology.

For customers the expectation around speed of delivery is already far beyond what is possible in the traditional data centre so SDN means the provision of cloud services can be brought more in line with what customers already think happens.