Choosing a virtual WAN optimization tool over a physical appliance is not simply an "apples to apples" comparison. Dedicated hardware appliances historically have been faster than their virtual counterparts, but the networking industry is changing. The shift towards a more software-centric environment is changing the requirements of enterprises, and speed is no longer the only consideration.
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Network engineers are choosing between virtual and physical WAN optimization tools to fulfill different use cases. Data flows that go between a branch office and data center differ from the flows between two data centers. Users will have different needs as a result, said Andre Kindness, senior analyst at Cambridge, Mass.-based Forrester Research Inc. "Hardware and software [WAN optimization] tools can't be simply compared because they are not being used in the same way -- they each solve different problems," he said.
Users in a branch office typically are opening more applications and sending more traffic to the data center that could require additional security and processing power. While hardware instances could work better in this use case, the flows between data centers typically are simpler and could need only a virtual appliance. "Virtual appliances would be slower in handling flows between the branch office and the data center because [they] would have to make many different decisions with the traffic," Kindness said. "Flows between data centers, however, talk to each other in a very regular pattern."
INgrooves, a San Francisco-based music distribution and marketing company that distributes albums and digital tracks to iTunes and other online stores, needed to cut down on the replication time between its main San Francisco-based data center and its disaster recovery (DR) site in Dallas, said Nicolas Ratineau, director of systems engineering at Isolation Network Inc., INgrooves' parent company.
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INgrooves is required to replicate every 30 minutes to their DR site, but the company's legacy hardware WAN optimization tools were only able to achieve complete replication every two hours or more, Ratineau said.
"Until now, we were just increasing the bandwidth to solve the problem. We were up to [1 Gbps], and increasing past this amount involved a lot of changes to our network, and a lot of costs," Ratineau said. "We knew we needed a more efficient [WAN optimization] solution."
Ratineau and his team downloaded the VX 9000 virtual WAN optimization appliance from Silver Peak and brought replication times down from every two hours to every five to 15 minutes, Ratineau said. "We were able to try the software appliance really quickly, and see the performance was great for us between our San Francisco and Dallas data centers," he said.
Physical vs. virtual WAN optimization tools: Which one to choose
While physical and virtual appliance deployments differ according to the use case, enterprises are becoming sophisticated enough to know when to use a hardware- or software-based tool, Forrester's Kindness said.
In addition to being an appropriate WAN performance solution for data-center-to-data-center flows, virtual WAN optimization tools also work well in a dynamic environment, Metzler, Ashton's Metzler said. "As loads increase and then shrink, some enterprises like the pay-as-you-grow mentality," he said. "Businesses have much more of an ability to grow with software than with hardware, and it's a lot easier to download a software tool rather than wait for hardware to be shipped."
While it still holds true today that dedicated hardware is faster than software, virtual WAN optimization tools have made inroads in recent years, Metzler said. "The industry is doing a lot with software, and the good news is that software is getting better than it used to be."
WAN performance tools aren't the only appliances undergoing a shift from hardware to software. Application delivery controllers, firewalls and software-defined data centers are pointing to the industry's movement to software-based tools.
"More functionality will be done in software, but it will happen incrementally," Metzler said. "We won't make that shift overnight."