Zero client technology is the latest trend in reduced footprint computing. Much like 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 users' desk. While thin clients require some local processing power and locally installed software, zero clients eliminate the need for locally installed software and connect directly to virtual PCs back in the data center, usually over an Ethernet connection.
Zero client hardware typically consists of a small box that connects to a keyboard, mouse, monitor and Ethernet connection. The zero client 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. When paired with a VDI (virtual desktop infrastructure), zero client solutions become a quick, secure way to deliver applications to users.
Zero client technology offers several advantages over "fat clients," which are also known as traditional PCs:
- Power use can be greatly reduced.
- A fat client may use as much as 250 watts of power, a zero client device may use as little as 5 watts
- 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
- When 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 this change, all of the management, support, continuity and failover benefits of a virtual infrastructure are extended to desktops throughout the organization
Fat Client
Thin Client
Zero Client
Interface ports
Robust
Seri...
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al: 0-8+
USB: 2-8+
Parallel:0-2
PS/2: 0-4
Display: 1-16
Limited
Serial: 0-2
USB: 2-4
Parallel: 0-1
PS/2: 0-2
Display: 1
Robust
Serial: 2-8+
USB: 2-8+
Parallel: 0-1
PS/2: 0-4
Display: 1-2
Reliability
Low
Hot (35-275W)
Many moving parts
Modest
Warm (15-40W)
Fans on some
High
Cool (5W)
No moving parts
Operating Systems
Windows XP / Vista
Windows 2000
Large: 128-512 MB RAM
Unstable
High virus risk
Windows CE
Embedded XP
Moderately large:
16-256 MB RAM
Moderately stable
Modest virus risk
Embedded
Small: 4-32 MB RAM
Simple
Stable
No virus risk
Client licensing
Windows XP
Windows CAL
Windows CE
Windows CAL
None
No CAL
Functionality
Applications
User interface
I/O
User interface
I/O
Terminal emulation
Remote access
I/O
Terminal emulation
Application support
PC dedicated
Native support
RDP / ICA to server
Must be rewritten
VDI to server
No modifications
Price per seat
Expensive
$400 to $2000
Moderate
$350 to $1000
Inexpensive
$99 to $300
Currently, only a few vendors are playing in the zero client space: Pano Logic Inc., Digi International, Wyse Technology and Teradici. Each of these vendors approach zero client technology in a unique fashion.
Pano Logic Inc. offers a small hardware device that works with VMWare's ESX Server hypervisor. 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 International approaches the zero client environment with its 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 Technology combines multiple technologies to deliver its zero client solution. This 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's 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. Teradici 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.
Zero client technology is still in its infancy, but should prove to have a significant impact on the enterprise as the technology evolves, becomes more accepted and better supported.
ABOUT THE AUTHOR:
Frank Ohlhorst
Frank Ohlhorst is an IT journalist who has also served as a network administrator and applications programmer before forming his own computer consulting firm.
