Monday, Jan 15, 2018
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VDI Deployments & WAN Virtualization: What You Need to Know

Many organizations have enjoyed the benefits of a Virtual Desktop Infrastructure (VDI) environment for some time now. As its popularity grows, even more are realizing what’s achievable through VDI and are considering deployment. Today, we’ll talk about what VDI is (yes, not everyone knows) why it exists, what to consider and how to best utilize VDI.

First, a quick definition for VDI. VDI is the hosting of virtualized desktops on a centralized server, with clients connecting to the server to access their individual virtualized desktop. There are a few common scenarios in which VDI is implemented. The first is within a single, local network, where both the clients and servers are at the same location. The second is a decentralized approach, where remote users or locations connect back to data centers where the virtualization servers are located. Typically, the remote side communicates with the datacenter either through private connectivity using technology such as MPLS, or via VPN. Of course this depends on the organization and its unique needs.


Depending on the organization, the benefits of moving to VDI have great potential. VDI is designed to have remote clients host their virtual desktop instances on a centralized hardware platform. The clients themselves need only to have some sort of terminal to view and interact with the virtual desktop, where all actual processing is done. This allows for potential cost savings in hardware, since the terminals themselves don’t have high hardware requirements. This also simplifies administration and allows for more efficient use of IT staffs’ valuable time. Rather than supporting each PC individually, nearly all maintenance can be done from the centralized controller. This also makes supporting multiple remote locations with a limited support staff far more manageable. Additionally, since the communication between client and server is reasonably predictable, it can make it far easier to “right-size” the WAN connectivity, protecting against overspending and paying for bandwidth that is not needed.

As just one example, EGAN, a $215 million dollar commercial construction company located in Minneapolis, saves over $100,000 per site annually in technology expenses by utilizing VDI.

Sounds like a great deal, right?

VDI Considerations

Like all great things, there’s a catch. Though the benefits mentioned above can be compelling, in order to have the best experience with a VDI implementation it’s important to address a few key considerations during the planning phase. In particular, with a decentralized approach, reliance on the WAN connectivity becomes a critical issue. If the WAN connectivity at a remote location fails, users lose access to their desktops – productivity, predictably plummets. Even worse, if the connectivity at the datacenter drops, it affects users at all of the remote sites! A scary prospect, indeed. That means loss of dollars and reputation– not just frustrated employees.

In addition to outages, poor performance (high latency, significant packet-loss, etc.) can be almost as bad, leading to frustrated users and, again, loss of productivity.

Utilizing Virtualization

These concerns can be addressed through the technologies associated with WAN Virtualization, a system in which multiple WAN connections are utilized via a controlling appliance. The idea of utilizing multiple WAN circuits at each location can seem daunting, especially for organizations using MPLS. However, WAN Virtualization typically allows for multiple, diverse connections types. Not just different carriers or technologies (i.e. cable, fiber), but a mixture of both private connection such as MPLS and public circuits such as broadband. When using public circuits, the WAN Virtualization solution should provide the ability to encrypt traffic from site to site to ensure security. With a WAN Virtualization appliance at each location, the multiple connections are constantly monitored for disruptions or fluctuations in line quality. If a WAN connection fails, WAN Virtualization should seamlessly move the established connections to the other WAN connection without disrupting the VDI sessions. Some WAN Virtualization solutions offer the ability to actually duplicate the traffic over each connection, ensuring an entirely seamless level of failover.

Alternatively, the multiple connections could be actively utilized in a load-balanced fashion, sending some of the traffic over one of the connections and some of the traffic over the other(s). An intelligent WAN Virtualization solution will make these load-balancing decisions intelligently — based on the capacity of the WAN connections, combined with a view of the current utilization on each connection, in order to make the best use of the pool of available bandwidth. The solution should also have the ability to set up static routes for particular traffic types – this can be handy if one of the connections has better overall line quality (for example, lower latency) and VDI sessions might achieve the best performance out that particular connection – again, assuming that connection is up. Most WAN Virtualization solutions can also prioritize traffic so that the VDI sessions can be allocated the bandwidth they need without being crowded out by less critical traffic types.

Finally, the visibility afforded by a WAN Virtualization solution can be extremely valuable in taking control of the WAN connectivity. Performance graphs and metrics along with troubleshooting tools can all take advantage of this increased visibility to allow for proactive optimization and configuration to best make use of the connectivity available to you at each site. Of course, having automatic alerts to inform you if a connection fails are critical as well, as the automatic failover achieved through WAN Virtualization means users shouldn’t notice the disruption.

Controlling Your WAN

With VDI comes a great deal of benefits, but when planning for implementation in a multi-site environment, the WAN becomes a critical piece. It’s important to understand the issues associated with placing the VDI sessions over the WAN, and how to evaluate a solution designed to address them. Taking control of the WAN is an important step to a successful multi-site VDI deployment.