Channel Insider's Guide to Zero Client Virtualization

By Frank Ohlhorst
Virtualization is changing how enterprises work. The technology has impacted storage, servers and now the desktop. Today many enterprise IT departments are extending the power of virtualization by turning to Virtual Desktop Infrastructure (VDI) solutions. When properly implemented, VDI moves the desktop operating system into the datacenter, turning the end point into little more than a terminal.

Some VDI solutions work with thin client applications, while others work via a web browser. Either way, a PC is still required to access the virtualized desktop in the datacenter. However, zero client technology is changing the way IT managers view end points. What’s more, zero client solutions create significant opportunities for solution providers looking to grab enterprise level clients, as well as reengineer SMB desktop services.

What is a Zero Client?

Zero client technology is the latest development in reduced footprint computing. Similar to a thin client, a zero client moves the computing power back to the data center, leaving little more than a keyboard and monitor at a user’s desk. However, traditional thin clients require some local processing power and locally installed software and that is where the distinction between a zero client and thin client lies.
The latest zero client solutions eliminate the need for locally installed software and connect directly to PCs (virtual or physical) back in the data center, usually over an Ethernet connection.

Nevertheless, the definition of a zero client device is still open to some interpretation. For example, vendor Pano Logic claims that a true zero client device has no operating system or processor. On the company’s website, Pano explains that it calls its devices "zero clients" because, unlike traditional thin clients, "they have no CPU, no memory, no operating system, no drivers, no software and no moving parts. They simply serve to connect peripheral input-output devices -- a keyboard, mouse, VGA display, and audio output -- along with other USB peripherals to a virtualized Microsoft Windows desktop operating system running on a server in the data center."

While that definition seems very specific, the industry has accepted that other devices still fall under the realm of zero clients – devices that have a small local OS and some processing power, mostly for connectivity issues, security and management.

A Closer Look: Zero Client Solutions

Zero client hardware usually consists of a small box that connects to a keyboard, mouse, monitor and Ethernet connection. The zero client device contains network protocols, allowing each of these interface types to be supported over a wired or wireless IP network without a local PC or thin client. Zero clients are connected over the network to applications running on a PC or server located elsewhere on the IP network. Zero clients when paired with a VDI (Virtual Desktop Infrastructure) solution become a quick, secure way to deliver applications to users.

Zero clients offer several advantages over "fat clients", which are also known as traditional PCs. With zero client technology, power use can be greatly reduced. Where a fat client may use as much as 250 watts of power, a zero client device may use as little as 5 watts. What’s more, zero client devices cost significantly less than a traditional PC or even a thin client device. Zero client solutions are often priced well under $200 per seat.

By combining zero client computing with VDI, administrators can reduce the number of physical PCs or blades and run multiple virtual PCs on server class hardware. With that change, all of the management, support, continuity and failover benefits of a virtual infrastructure are extended to desktops throughout the organization. That situation also bodes well for MSPs that are looking to delve into the hosted PC space.

Fat Client

Thin Client

Zero Client

Interface Ports


Serial: 0-8+

USB: 2-8+


PS/2: 0-4

Display: 1-16


Serial: 0-2

USB: 2-4

Parallel: 0-1

PS/2: 0-2

Display: 1


Serial: 2-8+

USB: 2-8+

Parallel: 0-1

PS/2: 0-4

Display: 1-2



Hot (35-275W)

Many moving parts


Warm (15-40W)

Fans on some


Cool (5W)

No moving parts

Operating Systems

Windows XP / Vista

Windows 2000

Large: 128-512 MB RAM


High virus risk

Windows CE

Embedded XP

Moderately large:

16-256 MB RAM

Moderately stable

Modest virus risk


Small: 4-32 MB RAM



No virus risk

Client Licensing

Windows XP

Windows CAL

Windows CE

Windows CAL





User interface


User interface


Terminal emulation

Remote Access


Terminal emulation

Application Support

PC Dedicated

Native support

RDP / ICA to server

Must be rewritten

VDI to Server

No modifications

Price per seat


$400 to $2000


$350 to $1000


$99 to $300

Currently, only a few vendors are playing in the zero client space. Those vendors include Pano Logic, Digi, Wyse, N-Computing and Teradici. Each of those vendors approaches zero client technology in a unique fashion.

Pano Logic
For example, Pano Logic offers a small hardware device that works with VMWare’s ESX Server hypervisor, where a virtual PC is created in the data center
and delivered over an IP connection to the Pano device, which handles transferring all I/O between the desktop peripherals and the hypervisor based PC.

Digi approaches the zero client environment with their PCoIP (PC over IP) based ConnectPort Display technology. With ConnectPort, a dedicated PC or blade is located in the datacenter and functions as the remote PC, all I/O is converted into an IP carried protocol which the ConnectPort Port Display device delivers to the user’s monitor, while all peripheral activity is passed back to the datacenter.

Wyse combines multiple technologies to deliver a zero client solution. The company offers their WSM appliance (or WSM provisioning software), which runs in the datacenter to deliver PC desktops out to the company’s zero client devices. WSM can be combined with virtualization to build out a VDI solution.
Teradici approach has its roots in PCoIP technology.

The earliest Teradici zero client solutions involved placing a PCI card into a host PC, which then redirected all I/O over IP to a piece of zero client hardware located at the desktop. The company has recently partnered with VMware to create a virtualized version of the host PC, which changes the zero client relationship from one user mapped to one physical PC to a one (virtualized PCs on server) to many relationship.


N-Computing combines the traditional zero client device with VDI in the form of their L300 solution. A small device sits at the user’s desk, which replaces the PC. That device uses IP to connect back to the datacenter, where a server is running N-Computing’s vSpace virtualization software provides the virtual desktop. The L300 can be further integrated with VMware or Citrix technologies to incorporate advance monitoring and management technologies.

The impact on the channel

Although Zero client technology is still in its infancy, it will have a growing impact on the enterprise, especially when one considers the savings of scale. As zero clients replace desktop PCs, operational, management and services costs will also decrease. The key for solution providers is to be ready for the transition and be able to step in when businesses seek to pilot zero client solutions. Solution providers will be able to provide hardware, software and most importantly, the services to make the pilot a success, which in turn build a customer relationship where the solution provider can offer a range of services and solutions. Those services and solutions include business continuity, disaster recovery, security, remote management and many more.


This article was originally published on 2010-04-27