By Fredrik Brattstig @virtualbrat
7 March 2024
Microsoft recently GA released Azure Virtual Desktop on Azure Stack HCI; the technology extends the Azure Datacenter to your on-premises service location, so you will be running your AVD hosts on-premises. It also gives the great benefit of using Windows 10/11 multi-session running from your on-premises data center. Read more about AVD on Azure Stack HCI here
The most crucial piece of technology to harvest the best possible performance from your Azure Stack HCI AVD workloads is to utilize RDP-ShortPath. Let me explain why:
A regular AVD session that does not use RDP-ShortPath uses TCP traffic for the session protocol. The TCP traffic will traverse the Microsoft Azure Gateways and find its way to the AVD host, and it will be a constant TCP flow over the gateways. This is OK when running your AVD workloads in the Azure data center, even though enabling RDP-Shortpath will give a better user experience, as RDP-ShortPath uses UDP traffic for the session, which reduces latency and increases the bandwidth availability for the session. But there is another advantage of RDP-ShortPath in the specific example of AVD on Azure Stack HCI.
First, let’s look at a very basic illustration of an AVD TCP Session:
We see a normal traffic flow between the IGEL and the AVD session. The session traverses the internet and also the Microsoft gateways. Nothing to complain about here!
When adding AVD on Azure Stack HCI, e.g., moving the AVD host from the Azure datacenter to your on-premises datacenter, the diagram looks like this using TCP session traffic:
We can see that the session traffic is very awkward, and it’s easy to see that this is not the optimal route for the session traffic flow. This is precisely where the RDP-ShortPath comes into play when running AVD on Azure Stack HCI. Let’s look at the diagram of the flow with RDP-ShortPath enabled:
Now, when we have established an RDP-ShortPath session to our on-premises AVD running on Azure Stack HCI, the IGEL OS endpoint will connect straight to the AVD host using UDP traffic and the session performance difference is dramatic.
The above image comparison shows Remote Desktop Analyzer, on the left-hand side shows a regular AVD session using TCP and running in Azure Datacenter. The right-hand side shows the metrics on an AVD session running on Azure Stack HCI with RDP-ShortPath enabled. As you can imagine, the reduction of latency from 68ms to 0ms and the increased available bandwidth, the session performance will improve greatly.
IGEL OS 12 AVD App has RDP-ShortPath enabled by default. It is a preview feature, I have been using RDP-ShortPath personally for at least a year now in my AVD sessions, both on-premises and in Azure Datacenter delivered workloads and it gives an amazing boost in user experience in both scenarios. I can only recommend enabling it!
If you want to read more about IGEL OS and AVD on Azure Stack HCI, find these articles:
https://virtualbrat.com/2023/06/20/want-to-test-azure-virtual-desktop-on-prem-heres-a-guide-taking-you-from-0-to-a-functional-single-node-azure-stack-hci-cluster-and-azure-gallery-images-installed-and-added-to-your-avd-environment/
Thats it! Happy UDP’ing!
/Fred
VirtualBrat 