VIRTUAL DESKTOP

nComputing

 

1. (2) Remote USB 2.0
2. Microphone
3. Headphone
4. Keyboard
5. Mouse
6. 10/100BASE-T Ethernet
7. VGA Monitor
8. 12V DC In
9. Power Switch

 

Architecture

nComputing has been around since 2003. In the technology world, this is a lifetime. nComputing sells terminals – access devices – that come in three basic flavors:

• X-Series: Direct. With X-series devices, a specialized PCI card is installed in the machine designated as the server. Individual access terminals are connected to the server with Category 5 cabling. The access devices allow users to connect their own monitor, keyboard and mouse. Don’t let the fact that the X-series uses Category 5 cabling fool you. This is not an Ethernet-based solution and terminals can’t be any further than 10 meters from the server.
• U-Series: USB. Many places have machines clustered into pods. In these kinds of scenarios, nComputing’s U-series access devices are a good fit. With this solution, you don’t need to worry about a specialized PCI card, but do need to make sure that the machine you intend to use as a server has enough USB ports to support your intentions.
• L-series: Ethernet. The L-series devices, specifically the L300, are the focus of this article. L-series devices connect to an Ethernet network and connect to a server located elsewhere on that network.

As I mentioned, the L300 is the device on which I will focus in this article. It carries a list price of $279, although that price can come down considerably when the devices are purchased in bulk. At the $200 mark or so, a terminal becomes a much more acceptable cost, particularly when that terminal can handle some advanced multimedia in reasonable ways, at least at LAN speeds. You will discover in this article that the L300 access devices are not a great WAN solution, but for many, that’s okay.
By the way, nComputing includes a vSpace (explained later) license with each L300 and there are no additional licensing costs for the solution from nComputing.

vSpace software

The vSpace software is another part of nComputing’s “secret sauce” solution. This software is installed on any supported Windows machine and virtualizes those resources that are necessary to provide a seamless session-based computing experience. Those resources are then shared among the many users that connect to the server.
Although I have not tested it, vSpace is also supported on Ubuntu Linux systems, making Ubuntu a choice for terminal-based computing as well.
vSpace is installed on top of an existing copy of Windows; both desktop and server editions of Windows are supported. Before you jump too quickly, however, make sure you understand Microsoft’s licensing restrictions. You need to have Windows Server licenses and client access licenses (CALs) as well as Remote Desktop Services CALs. Read more about the licensing restrictions here.
To learn more about the vSpace software, watch nComputing’s video on the topic here.

User eXtension Protocol (UXP)

UXP is nComputing’s own protocol for handle remote screen display. This protocol works in conjunction with the vSpace software and the nComputing terminal to provide a really good end user experience.  In my own testing, the office work experience was indistinguishable from a regular PC. When it comes to multimedia – browsing YouTube and Flash sites, for example – I’ve been very impressed with the performance of the nComputing solution. Both low- and hi-def video works well. Standard definition video is just about perfect. High def video can get choppy, but not very often and not so bad that it would negatively affect casual usage.
Perhaps the only downside of the UXP protocol lies around bandwidth usage. A single client can consume up to 15 Mbps of network bandwidth, making the solution unsuitable for WAN deployments. Further, this level of bandwidth usage might limit large LAN deployments, too. That said, your users won’t be pushing that maximum bandwidth load 100% of the time. On a 1 Gbps network link, you won’t run into major problems unless you try to place 50 or 60 units on a single link and everyone is pushing their devices to the max. If your users are doing nothing more than general office work, I doubt that you will see a 15 Mbps impact.

L300 at-a-glance

In the image below, you will see a picture of the L300 showing all of its various ports.

Figure 1: L300 connections
Note that there are two USB 1.1 ports designated for the keyboard and mouse and two “remote USB 2.0” ports. The two USB 1.1 ports are pretty self-explanatory, but let me go into a bit of detail about the two USB 2.0 ports. First of all, don’t expect USB 2.0 speeds out of the terminal. USB 2.0 operates at speeds of up to 480 Mbps. If the terminal supported these kinds of speeds, scalability would be severely limited. Expect USB 1.1 speeds. If you connect a massive hard drive and copy a huge file from that drive to a connected session, you might be waiting for a while since the device’s USB 2.0 ports operate at 1.1 level speeds (think 10 to 12 Mbps).
Second, not all USB devices will work with the L300. I’ve tried by USB flash drives and web cams.  While flash drives worked just fine (albeit, a bit slowly), web cams didn’t work at all. I asked nComputing and  they explained that isochronous USB devices aren’t supported by the L300 nor are they supported by many other thin client solutions. Isochronous USB devices are expected to operate at a guaranteed data rate, which is often pretty high. Real-time audio/video support, as used with web cams, can’t handle the lack of guaranteed bandwidth and the low speeds provided by the L300 and other thin clients. When you really think about it, this makes sense, too, as scalability would be severely limited.
Even with these limitations, the L300, in my opinion, remains a very viable contender in the VDI race.
Of course, lack of support for some USB devices eliminates the possibility for the L300 to be deployed in certain scenarios that require this kind of support.

System requirements

When it comes to density, you can do a pretty good job with the L300. In the system requirements table below, you’ll notice that the L300 supports 30 terminals per host with only very modest requirements needed for the “server” hardware. Since nComputing supports the use of beefed up desktop computers as a server, this can be a pretty low cost solution that performs very well.

Number of terminals	1-3	4-7	8-10	10-20	20-30
CPU	Core 2	Core i5	Core i5	Core i7	Core i7
RAM (32-bit)	2 GB	3 GB	4 GB	4 GB	4 GB
RAM (64-bit)	3 GB	4 GB	6 GB	6 GB	8 GB