Original URL: http://www.theregister.co.uk/2013/02/28/datacentre_sdn/
Let software take the strain off your data centre
Provisioning made easy
Software-defined networking (SDN) may not yet be at the top of your data centre to-do list but if you want the benefits of private cloud, it should be soon.
Our recent Regcast, during which HP discussed SDN and “virtual application networking” (the concept name for how it sees SDN and virtual networks developing), provides a good introduction.
For those who do not have an hour to spare right now, here’s part of our discussion, summarising why if SDN did not exist we would need to invent it.
We provision networks in the same way as we did in the 1990s. Server virtualisation means that servers are no longer tied to hardware, but tell that to your networking guys. Their provisioning is still tied to hardware, relies on scripting and can take days or even weeks, with all the human error that can result.
No one can expect to deliver cloud efficiently this way. On the one hand, it fails to make efficient use of either your hardware or your time. On the other, it becomes a provisioning bottleneck. The sort of dynamic IT that makes a cloud useful cannot exist in this static networking environment.
SDN allows you to define what each virtual server, or better still each application, requires from the network and then does its best to provide it.
One of the most exciting elements of SDN is that it is open. It is still early days – the Open Networking Foundation was founded only in 2011 – but with OpenFlow integrated in switches as standard, interoperability between vendors and unified management are plausible.
HP’s Intelligent Management Centre (IMC) software has been integrated with vCenter, for example, allowing management of virtual and physical networks to be done from the same application.
In HP’s vision, there are three stages to reconfiguring a data centre network using IMC’s Connection Manager. First, you characterise what each virtual server or application requires in terms of bandwidth, peak information rate and so on.
Being able to do this at the application layers means that, for example, you can specify different QoS levels for VoIP and email if they reside on different virtual machines. When a system admin migrates a virtual machine to a new location, the management software configures the physical switches automatically.
One step at a time
One question we are always asked when we do a Regcast about a new technology trend, especially in infrastructure, is “where do I start?”.
Clearly, under the pressure of constrained data centre budgets, SDN would win few friends if it meant first tearing out your existing network fabric.
Freeform Dynamics has recently done research on the Reg readership’s approach to innovation. It showed that the most popular way to improve the data centre is by incremental modernisation, updating gradually to a plan. The big bang approach is the least popular.
So there is comfort in knowing that SDN is not a rip-and-replace concept. It is perfectly feasible to use SDN alongside traditional networking, maybe for years, depending on what you need and what type of switches you already have in your data centre.
Over-enthusiastic marketers can give the wrong impression
There may be some areas of the business where flexibility is not very important or where the business is unwilling to invest.
Reconfiguring your data centre is not something you take on lightly, and over-enthusiastic marketers can give the wrong impression of the promise of virtual networking. So there is also reassurance in knowing that SDN offers the possibility of modelling the impact of any reconfiguration before it is implemented.
SDN can make a network more efficient but it can’t magic capacity from thin air. Somewhere in your data centre there will be a constraint on the application performance the business desires, and SDN may show that it can be removed only by hardware investment rather than better management.
Free the admins
If SDN doesn’t magically give you all the capacity you need, it does help you to see where your constraints might be and to make decisions based on the principle of second-best, rather than “let’s not touch that while it is working”.
As ever, this promises to change the working lives of network admins. Less scripting, fewer repetitive tasks and less time chasing down the effects of human error can lead to radically different working patterns (although the skills required are not hard to pick up).
For teams accustomed to a process that lasts for days, provisioning in a couple of hours makes for more interesting work, allowing networking admins to be proactive rather reactive.
Freeform Dynamics tell us that half of Reg readers expect to deploy a private cloud within less than five years. The flexibility that private cloud demands could mean a lot of wasted weekends for network admins – unless we find a better way to manage the network.
After all, no admin will want an epitaph that reads: “I wish I had done more scripting”*. ®
* On second thoughts, Trevor Pott might