Now that doing more with less has evolved from a strategy to a way of life within many IT departments, few technologies are getting a bigger boost than wide-area-network optimization controllers , or WOCs.
WOCs, also known as WAN optimizers, can be implemented as appliances or software applications. Either way, they work toward one overarching goal: making WAN links faster and more reliable without forcing organizations to spend more on bandwidth.
These controllers work by blending enhanced transmission control, data compression and data caching techniques to manage traffic moving across WANs  and keep the volume of information to a minimum.
Why are businesses now seeing WOCs in a new light? They address some of the most significant transformations occurring within IT infrastructures today:
Data-center consolidation: Centralizing IT infrastructures reduces management overhead and helps hardware run closer to its rated capacity. But this is practical only if business users in branch offices don’t see slower performance when their servers aren’t running locally any longer.
That’s a big “if” without WOCs. The farther away servers and data reside, the more pressure WANs must bear as everyone competes for limited bandwidth. Another challenge is latency, the performance delays that crop up when clients and servers communicate over long distances.
Video: As live, on-demand video becomes a go-to technology for communications and training efforts, organizations are looking to WOCs to keep network channels flowing freely.
“Among the trends that are driving WAN optimization to the next level, by far the biggest is video,” says Mark Urban, senior director of product marketing for Blue Coat Systems. “And that has an impact on WAN costs and the performance of other applications.”
WOCs help by reducing network traffic and opening more bandwidth for latency-sensitive video transmissions. Some appliances can broadcast video to branch offices by hosting and sharing their processing power with media servers that feed video streams to conference rooms and desktops.
All of these considerations encourage companies to think differently about how they use and implement WOCs. “IT managers are no longer seeing WAN optimization as something they bolt on,” says Andrew Harding, senior director of product marketing for Cisco Systems. “It’s something they plan for in their network designs.”
WOCs work by taking a multipronged approach to optimizing WAN traffic. The first step is to compress data to keep volumes as low as possible. This keeps pipes from becoming overloaded and reduces transmission times.
For added performance, WOCs also cache information by storing files in local repositories — either in WOC appliances themselves or in networked storage systems. For instance, the first time someone in headquarters relays a large presentation to a branch office, the WOCs would save a local copy.
Subsequently, when a remote user requests the presentation, it’s delivered from that location rather than by traversing the WAN. The two WOCs can even communicate with each other to see if the presentation has been updated, and, if it has, headquarters will download only the changes to keep redundant data from straining the network.
WOCs can overcome the cacophony of the ubiquitous Transmission Control Protocol (TCP) and other “chatty” network transport standards that require clients and servers to send multiple instructions and acknowledgements to one another in the process of exchanging data packets.
The time between when messages are sent and when they’re received can unnecessarily delay WAN transmissions. WOCs step in and handle many of the acknowledgement messages that typically have to travel across the wire. They’re also designed to overcome the fail-safe measures of TCP when the protocol mistakenly slows traffic as it senses network congestion.
Protocol optimization doesn’t stop with TCP. Many WOCs can use local message caching and other performance-boosting techniques on other talkative protocols, such as Common Internet File System (CIFS), Server Message Block (SMB) and Messaging Application Program Interface (MAPI).
As audio and video data on networks continues to grow, organizations have to do more than just keep network pipes clear: Time-sensitive information needs special treatment.
Built-in quality-of-service capabilities in WOCs do this in a couple of ways. First, QoS limits available bandwidth to data packets that won’t be bothered by slight transmission delays. Second, QoS tools identify traffic that will receive top priority if bandwidth is in short supply.
Finally, WOCs can act as an early-warning system for network administrators by constantly monitoring messages flowing among headquarters, branch offices and remote users. When transmissions begin to slow to unacceptable levels in a WAN segment, WOCs sound an alarm before gridlock occurs. Similarly, some WOCs provide reports to help network admins identify chronically slow spots.
With WOCs playing such an important role in addressing emerging IT challenges today, organizations need to choose the right optimization solution for their needs. WOC manfacturers advise administrators to focus on six considerations when evaluating solutions.
Check for certification. Pay particular attention to how the WOC works with existing storage systems and individual enterprise applications.
“Many of our clients compile a white list of applications that have been certified by the software vendors to work well with the optimization controller,” says Eric Siegel, research director for networks and telecommunications at Gartner. “Over time, the clients go back to the applications that are not being optimized and put them through the lab. If they work, then those programs are added to the list.”