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Hardware vs. software WAN optimizers: Advantages and disadvantages of each form factor

The spread of unified communications and the rise of cheaper but lossier/less-consistent WAN connectivity are driving increased interest in deploying WAN optimization more broadly. WAN

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optimization is one of the cornerstones of application delivery optimization (ADO). WAN optimizers focus on the problems of boosting application performance over wide area networks through techniques like application acceleration and data compression.

WAN optimizers come as hardware or software; WAN optimization can also be delivered as a service. IT needs to weigh the advantages and disadvantages of each form factor to decide which WAN optimizer to deploy -- hardware vs. software. In this article we’ll discuss physical and virtual WAN optimizers; in the next, we'll discuss client and cloud WAN optimization.

Physical hardware WAN optimizers

The advantages
Deploying a dedicated physical appliance that can compress and accelerate traffic brings to bear a potent combination of power and control. In a neatly separate layer of the network, IT can scale up to meet demands for throughput while maintaining a solid separation of duties in the network and complete control over the platform. The technology is well understood and widely deployed (68% of companies use it). However, it is not without its drawbacks.

The disadvantages
You have to put an appliance on each site to be optimized. This increases per-site capital expenditures and the time to deploy; each branch is “heavier” by one more box in the wiring closet and therefore that much harder to turn on or shut down.

As the director of networks at a large university put it, “Added boxes are bad.” You have to manage them all of your network equipment. IT takes on both asset and operational management of another layer of appliances, and a new vendor relationship about two thirds of the time. This adds real complexity to the environment, and one more skill set to maintain.

Hardware WAN optimizers are more difficult to scale up, because they increase complexity, and capital and operating. 

Virtual software WAN optimizers

The advantages
Software WAN optimizers transform physical appliances into another set of virtualized workloads, and allow for hosting optimization along with other workloads on shared hardware.

As with virtualization in other operational areas, leaving dedicated single-task hardware behind can reduce capital and operational costs, especially as a deployment scales. Without boxes to ship and install, you can deploy virtual WAN optimizers to many branch office locations more quickly, easily and cheaply -- if a host device with sufficient capacity to spare is present where needed. This speeds up testing as well as production deployment. On the data center side, virtualization can be more easily focused on a specific set of applications and can float to follow them as they move around and among data centers and even external cloud infrastructure.

The disadvantages
However, using virtual appliances does require that network resources be available, whether in a host server or in another appliance -- such as a router or application delivery controller. Software WAN optimizers can have significantly lower throughput capacities than dedicated boxes. And, of course, though they tend to be cheaper than hardware, they are still a capital cost with all the challenges that implies for scaling out.

Hardware vs. software WAN optimizers: How to choose?

In the end, IT needs to balance throughput requirements against scalability, infrastructure availability, and your desire to neatly modularize network functions. Where IT would have to deploy virtual machine hosts in places it did not otherwise plan to, a virtual WAN optimization appliance is not recommended. Where capacity is available and IT wants to spread WAN optimization widely, virtualization has more to recommend it. Where risk-management constraints require separation of duties in network layers, virtualization may be off the table until a need arises that a physical box simply can’t address.

When an installation has to scale, IT needs to be sure the chosen solution has very strong centralized management that can transparently and seamlessly handle the mix of physical and virtual WAN optimizers it settles on.

This was first published in September 2012

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