IMPORTANT UPDATE: It seems to me that some people are taking my article as if PCoIP does not work over 3G and Local LAN at the same time without being tuned. That’s not the case. PCoIP is a very smart display protocol and has the ability to tune itself automatically for most network conditions, from low bandwidth to high jittering and high latency. To be honest, almost ALL WAN and 3G deployments will fly and have excellent performance without any specific tune up. The tuning you read below is specific to very critical conditions where bandwidth is very scarce. I particularly see as beneficial the ability to fine tune the protocol according to the use case, however out-of-the-box there is not need for that for most deployments.
I could not wait to put my hands on the new VMware View 4.6 iPad client and test the app’s user experience using PCoIP display protocol. Finally last week we were all able to download and test the GA product. As soon we connect to the virtual desktops using the PCoIP gateway we start to understand and feel the differences between the PCoIP client and other RDP clients, such as the Wyse Pocket Cloud. The client is sleek with easy to learn gestures.
The experience is great over a 802.11g Wi-Fi hotspots connected to the local LAN with a theoretical 54 Mbps speed can be achievable. First, 54 Mbps represents a theoretical maximum only. It includes a significant overhead from network protocol data that Wi-Fi connections must exchange for security and reliability purposes. The actual useful data exchanged on 802.11g networks will always occur at lower rates than 54 Mbps. Anyway, it is more than enough for a true multimedia PCoIP session.
When we take the iPad to the outside world, unless we are at a Wi-Fi hot-spot, you we are most likely connected via a 3G network. An average 3G broadband speed of around 2Mb will be more than enough for most graphic PCoIP tasks. In fact, a speed of 512Kb is enough for all day-to-day tasks, such as web browsing, office applications etc.
The problem with most deployments is that it is not possible to guarantee bandwidth over internet and/or 3G, especially in big cities where blind spots are often common. Any hop of the transmission path could potentially be reducing the PCoIP throughput.
The picture above simply identifies a bottleneck at the organisation’s internet gateway that will affect the end user experience. As I mentioned before the bottleneck could be in any of the hops in-between the virtual desktop and the iPad client.
Because of these unknowns it is important to profile the PCoIP software to deal with such scenarios. I have previously discussed how to tune PCoIP for WAN connectivity in Optimising PCoIP Display & Imaging. Using GPO and Registry changes it is possible to profile PCoIP to consume less bandwidth, as an example, reducing the number of frames per second, or reducing the maximum initial image quality. (Read the article mentioned to get a better understand on how to do that). Another technique discussed at PCoIP: Unleash the Throughput helps to avoid PCoIP connection throttling.
Now I will get to the point of this article.
All these parameters and configurations will help you to reduce bandwidth consumption and benefit the user experience for iPad over 3G and/or internet. However, these parameters applied via GPO or registries are Computer Based. That means that the settings will be applied to the desktop in use every time the user connects from iPad via 3G or internally via LAN or local Wi-Fi hotspot.
A simple way to make sure these settings are applied only when required is to create dedicated desktop pools for users connecting from the internet, and dedicated desktop pools for user connecting from local LAN or internal Wi-Fi hotspot. Each desktop pool should place virtual desktops in its own Organizational Unit with its own set of Group Policies.
The downside is the management of two desktop pools, the requirement for floating pools and use of roaming profiles. In a scenario like that, persistent pools with persistent disks would not be available, at least for users coming from the internet. Luckily VMware View provide the ability to use TAGS to specify what pools should or should not be present to specific connection brokers.
The VMware View Architecture Planning Guide demonstrates this scenario on chapter 5.
This same guideline and considerations are applicable to any internet incoming connection, however because of the iPad client I believe more people will adventure themselves on virtual desktops over 3G networks; and if the connectivity isn’t properly designed it could lead to users complaining about the whole experience.
In my home lab I run graphic intensive applications over 3G (nor should you) and I have set the parameters as per below:
- 12 FPS (Frames per Second)
- Minimum Quality Image = 30
- Maximum Initial Quality Image = 70
- Bandwidth Floor = 100 Kbps
UPDATE: The settings I have selected for my homelab are there because my ADSL2 outbound link allows me only 100kbps, which is not quite enough for a full blown PCoIP multimedia experience.
Only if you face network congestion with low bandwidth or high latency I recommend you to play a little bit with the settings to understand how they impact on user experience and bandwidth consumption over 3G connections.