Networking

WAN critical to virtualization’s payoff

Guaranteeing application performance over a WAN is hard enough. Now try doing it in a virtual environment.

WAN optimization vendors big and small are developing versions of their products specifically for guaranteeing performance of virtualized applications delivered to remote offices from data centers. In so doing, they are looking to address challenges companies face in providing LAN-like performance for application delivery while availing themselves of the reduced cost and increased flexibility that virtualization provides.

“The biggest issue when you're looking at virtual traffic is the fact that, much like voice, much like video, it's live,” says Chris Silva, an analyst at Forrester Research. “If you're accessing it remotely and there's a glitch, you may have an application timeout, you may literally lose connectivity. It's really critical to have real-time interaction speed with that environment when you're working in it virtually. Think about it like any other live, real-time protocol.”

Desktop virtualization products like VMware's Virtual Desktop Infrastructure (VDI) are designed to replace traditional PCs with virtual machines managed from the data center. The potential benefit is a reduction in operating cost, increased control of desktop management, and extension of critical services, such as business continuity and disaster recovery, to enterprise desktops.

But when desktop virtualization is deployed over the WAN, latency and bandwidth constraints limit its effectiveness. According to Cisco, which has an arrangement with VMware for optimizing VDI over the WAN, customers face several challenges in deploying virtual desktops:

* Poor performance of Microsoft's Remote Desktop Protocol (RDP) over the WAN.

* High bandwidth consumption.

* Limited scalability, reducing the number of users that can be supported.

* Poor performance of centralized printing and increased costs of printing at the branch office.

* Considerable time and bandwidth required for transfer of virtual images.

* Continuous availability needed within and across the data center for the VMware VDI.

* High server resource consumption for SSL functions, resulting in a large number of servers.

Cisco says its Wide Area Applications Services (WAAS) product can accelerate the performance of all applications accessed through VMware VDI, including Microsoft Exchange, PowerPoint, Excel and Word, by reducing RDP bandwidth demands by 70%. The company also says WAAS can increase by fourfold the number of VDI users an infrastructure can support, and improve print operations by 70%. The appliance is designed to accelerate virtual image backup by 50 times, thereby reducing bandwidth by 90% for business continuity functions; and providing a 60% to 70% reduction in overall bandwidth requirements.

Crowded market

Other competitors in this market include Citrix and Riverbed. A host of smaller players also are fighting for their share.

Among them is Dimension Data, an integrator and reseller of Cisco's WAAS appliance integrated with Microsoft Windows Server. Its offerings address the reality that VDI environments force users to deal with different application behavior and bandwidth requirements than a physical or local hosting infrastructure.

“The impact of virtualizing technology from many physical infrastructures into one is that you'll need greater bandwidth,” says Lawrence Van Deusen, national practice manager for network integration at Dimension Data North America.

But greater bandwidth alone is not enough, Van Deusen notes. It must also be optimized for the unique behavior of VDI flows.

“[Users need to assess] new traffic patterns, and the impact the traffic has in terms of the capacity to support everything coming back to the data center,” he says.

Another player is the VDI WAN optimization market is Certeon. It makes virtual appliance software that runs natively within a VM infrastructure and is designed to provide application acceleration and WAN optimization to remote sites.

The company's aCelera software runs on standard x86 systems and is supported by Microsoft's Windows Server 2008 Hyper-V and VMware ESX and ESXi hypervisors.

The software is designed to reduce application response time and enable WAN optimization without requiring the space and expense of separately managed, single-purpose boxes.

“We took a Layer 7 approach where if you could understand the application and the objects of the application, then you could do a better job at acceleration,” says Gareth Taube, vice president of marketing. “We fit right in with the corporate strategy to virtualize applications, to get the savings and control from data center consolidation.”

Still, there are unique considerations when optimizing bandwidth for virtual rather than physical applications. The application itself has to have a small footprint because it will be sharing a hardware platform with other VM applications, Taube notes.

And the efficiency of the WAN accelerator is critically important, he says, because it has to be well integrated with the entire VM infrastructure – even though the infrastructure is largely virtual in nature.

“The real payload in WAN acceleration is the differencing [between virtual images of an application] that prevents you from sending the same data twice,” Taube says. “And the biggest impact of that is how much memory and disk you have to store this history so you can do the matching. So it's very important to work tightly with the virtual infrastructure so you have dynamic provisioning of this, and so you can provision your acceleration application to be optimum to the user population you're servicing.”

Other challenges arise in gaining visibility into and control over optimizing WAN bandwidth and application performance in VDI environments, according to Streamcore, a developer of monitoring systems for WAN optimization and application acceleration appliances.

With visibility, users need to understand how desktop virtualization is used throughout the WAN; they need to be able to follow the user experience; and they have top be able to detect if specific branch offices suffer from degraded performance.

For control, users have to optimize tasks in the face of voluminous VDI traffic, and protect VDI traffic competing with other types of flows in the network.

“The more you virtualize, the more you need tools to understand what's going on, measure performance in real time, and act on traffic,” says Christophe Peretou, Streamcore's vice president of operations. “We see virtualization as a new set [of requirements] where people cannot forecast the behavior of applications. There are too many variables today to do that. Virtualization presents a more complex scale. They need tools to report what's going on and to automate response to guarantee quality.”

Conditioning WAN links for VDI is how users will get the most bang for the buck from virtualization, Certeon's Taube says.

“The only way our biggest customers have found to be able to get the true ROI of virtualization is by making sure that they have application acceleration across the WAN as part of the project,” he says.

“If I can benefit from VDI, that's great; if I can benefit from it over the WAN, that's gravy,” says Jon Oltsik, an analyst at Enterprise Strategy Group.

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