This content is part of the Essential Guide: Troubleshooting tips for VDI deployments

Dealing with the VDI bandwidth dilemma

Limited bandwidth is the archenemy of a successful VDI. But before you turn to bandwidth optimization tools, make sure to calculate the amount of bandwidth you have -- and need.

This is the third section in our e-book on virtual desktop infrastructures. Part 1: The big picture | Part 2: RDP...

| Part 3: Bandwidth issues

Most organizations have limits on how much bandwidth they can make available for virtual desktop infrastructure (VDI) implementations. VDI vendors have been trying to solve the bandwidth dilemma by improving protocol performance and enhancing compression schemes. But improvements only go so far: At some point, bandwidth ultimately becomes the limiting factor in a successful VDI.

For most organizations, the bandwidth dilemma rears its ugly head over the wide area network (WAN) -- where many have come to rely on leased lines or third-party "pipes" to link remote offices back to the data center. Further complicating the bandwidth conundrum is the fact that those links are often shared by multiple technologies -- from traditional data transmission and Voice over IP (VoIP) to videoconferencing solutions -- all of which fight for the most bandwidth to deliver the best end-user experience for a particular service.

VDI solutions that scale out can find some relief with bandwidth-optimization technologies. The primary concept behind bandwidth optimization is to manage bandwidth and reduce unneeded traffic while creating a fully optimized "pipe" between locations. Several vendors do this by prioritizing traffic, reducing latency, eliminating TCP chatter and using a quality-of-service component to reserve certain bandwidth levels for specific applications. Those enhancements have a measurable effect on the performance of display protocols, VoIP and videoconferencing systems.

More on VDI bandwidth

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Bandwidth-optimization hardware and software can pay for themselves by reducing or even eliminating the need to purchase more bandwidth, but most administrators will find these offerings complex and the selection difficult. Performing the appropriate due diligence will help align expectations with product capabilities.

Don't guesstimate your bandwidth use
Before diving into product evaluations, consider performing a needs analysis. For VDI deployment, calculate those needs including the amount of bandwidth required and what's available to begin with. Fortunately, most VDI vendors provide the proper tools to evaluate bandwidth requirements, which are based on the protocols used, the number of concurrent virtual desktops, the applications offered and the anticipated levels of app use.

Calculating the available bandwidth, on the other hand, may not be as simple. In most cases, administrators will have to run performance measurement tools and define test procedures to calculate the available bandwidth over the WAN.

The next step is to align product capabilities with optimization needs. A good starting point comes from determining the basics and evaluating best practices. For example, you may want to build a list of product "must haves" and then determine which products best meet these needs. For an optimization product to offer full value for VDI, it should do the following:

  • Lower costs by reducing WAN bandwidth requirements to support VDI.

  • Significantly improve end-user response times.

  • Enable coexistence of desktop virtualizations and other WAN usage.

  • Improve application response time and performance.

  • Reduce network operating expense requirements.

  • Incorporate data protection and disaster recovery methods.

  • Enable simplified operating system and software deployments, upgrades and patches.

  • Improve security and compliance.

  • Provide compatibility with offline desktop operations.

Know the market leaders A few vendors offer products that are designed to optimize bandwidth specifically for VDI and have many of the aforementioned capabilities. The following vendors are just a cross-section of what's available on the market, so competition should make the products more efficient and more affordable over time.


Riverbed Technology Inc.'s Steelhead appliances increase WAN performance by improving the performance of all TCP traffic. They offer benefits to more than just VDI implementations and come in multiple models, segregated by environment size.

Expand Networks Inc. has several products that optimize WANs and reduce contention. Notable is Virtual Accelerator, a product you can deploy as a virtual appliance. Its "warm cache" technology enables both acceleration and failover capabilities. The company also offers traditional appliances with various capacities that you can deploy in the data center or at a branch office.

Cisco Systems Inc.'s technologies can be used to accelerate WAN links for VDI. Core acceleration technologies include Cisco Wide Area Application Services (WAAS) and Cisco Application Control Engine (ACE). WAAS increases the scalability and number of VDI users supported over the WAN; ACE improves the availability and scalability of data center VDI.

Silver Peak Systems Inc. has a family of appliances that are engineered for WAN acceleration. They incorporate robust management tools designed to solve problems associated with data replication, network backup, disaster recovery, server centralization and application delivery. This technology also optimizes WAN links used for VDI deployments.

Blue Coat Systems Inc. offers a combination of products that work together to accelerate WAN connections. The company relies on its Proxy SG appliances, which it pairs with its PacketShaper, Director and ProxyClient technologies for WAN optimization. Those products offer acceleration via hardware and software and could greatly improve VDI performance.

Frank Ohlhorst is an IT journalist who has also served as a network administrator and applications programmer before forming his own computer consulting firm.

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