Desktop’s HDX Channel Test

As already mentioned, the key factors influencing user experience in a virtual desktop infrastructure are the latencies experienced by the user while connecting to the desktop via ICA and the bandwidth used when a user interacts with a virtual desktop. High latency and excessive bandwidth consumption can often slowdown access to desktops, thereby significantly delaying subsequent user operations. Hence, monitoring the latency and bandwidth usage of the ICA communication channel between the user terminal and the virtual desktops is essential.

The Desktop's HDX Channel test auto-discovers the Windows virtual desktops on the cloud and the users who are currently connected to each desktop. For each such user, the test monitors the communication between a user and the virtual desktop, and reports the following:

The latency experienced by each user session;
The bandwidth used by the incoming and outgoing data/audio/multimedia traffic transacted by the ICA communication channel between each user and virtual desktop;

Using this test, an administrator can identify user sessions that are being impacted by high latency and abnormal bandwidth usage. In addition, the test also reveals the type of traffic that is causing excessive bandwidth usage, thereby providing pointers to how the client configuration can be fine-tuned in order to reduce bandwidth consumption and improve performance.

This test is disabled by default. To enable the test, go to the enable / disable tests page using the menu sequence: Agents -> Tests -> Enable/Disable, pick Cloud Desktops as the Component type, set Performance as the Test type, choose this test from the disabled tests list, and click on the >> button to move the test to the enableD tests list.

Note:

This test will report metrics only if the following conditions are fulfilled:

The Windows virtual desktops being monitored should be managed by XenDesktop Broker.
The Virtual Desktop Agent software should have been installed on the Windows virtual desktops.
The ICA Session performance object should be enabled on the Windows virtual desktops.

Target of the test : A Windows virtual desktop on the cloud

Agent deploying the test : A remote agent

Outputs of the test : One set of results for every user who is connected to a virtual desktop via ICA

Configurable parameters for the test
Parameter	Description
Test Period	How often should the test be executed.
Host	The nick name of the Cloud Desktops component for which this test is to be configured.
Port	Refers to the port at which the specified host listens to. By default, this is NULL.
Inside View Using	To obtain the 'inside view' of performance of the cloud-hosted Windows desktops - i.e., to measure the internal performance of the Windows virtual desktops - this test uses a light-weight eG VM Agent software deployed on each of the desktops. Accordingly, this parameter is by default set to eG VM Agent (Windows).
Report Powered OS	This flag is relevant only for those tests that are mapped to the Inside View of Desktops layer. If this flag is set to Yes (which is the default setting), then the 'inside view' tests will report measures for even those Windows virtual desktops that do not have any users logged in currently. Such desktops will be identified by their name and not by the username_on_virtualdesktopname. On the other hand, if this flag is set to No, then this test will not report measures for those Windows virtual desktops to which no users are logged in currently.
Is Cloud VMs	Since this test runs for a 'Cloud Desktops' component, this flag is set to Yes by default.

Measurements made by the test

Measurement

Description

Measurement Unit

Interpretation

Screen refresh latency - avg:

Indicates the average time interval measured at the client between the first step (user action) and the last step (graphical response displayed) of this user's session.

This measure maps to the 'ICA RTT' measure in Citrix Director.

Secs

This is a measurement of the screen lag that a user experiences while interacting with a virtual desktop.

Comparing the value of this measure across users will enable administrators to quickly and accurately identify users who are experiencing higher latency when interacting with a virtual desktop.

Screen refresh latency - deviation

Indicates the difference between the minimum and maximum measured latency values for this user session.

Secs

Ideally, the deviation in latencies over a session should be minimum so as to provide a consistent experience for the user.

Screen refresh latency - last:

Represents the client latency for the last request from a user. The latency is measured based on packets sent to and from each user during a session - this includes network delay plus virtual desktop side processing delays.

Secs

A consistently high latency may be indicative of poor user experience with the virtual desktop. Possible reasons for an increase in latency could be increased network delays, network congestion, etc. Typically, latencies will be below 5 secs.

Audio bandwidth input:

Indicates the bandwidth used while transmitting sound/audio to this user.

Kbps

Comparing these values across users will reveal which user is sending/receiving bandwidth-intensive sound/audio files over the ICA channel.

To minimize bandwidth consumption, you may want to consider disabling client audio mapping.

Audio bandwidth output:

Indicates the bandwidth used while receiving sound/audio from this user.

Kbps

Bandwidth used for video encoding

Indicates the amount of bandwidth consumed for encoding and transmitting video content in this user’s session.

Mbps

High values suggest video-heavy workloads that may require bandwidth optimization.

Frame backlog

Indicates the amount of time required to process, transmit, or render the display frames that are currently queued for this user’s session.

Seconds

A high value indicates a buildup of pending frames in the Thinwire display pipeline, suggesting encoding, network, or client-side rendering delays that can lead to screen freezes, increased display latency, and poor user experience.

Time taken to encode a frame

Indicates the average time taken by the server to encode a single display frame for this user’s session.

Seconds

Higher values may indicate CPU bottlenecks or graphics processing constraints on the host.

Thinwire session degradation factor

Indicates the percentage of display session degradation experienced by this user due to Thinwire performance issues, such as latency, frame backlog, bandwidth constraints, or encoding delays.

Percent

A higher value for this measure indicates that the user’s Thinwire session is experiencing noticeable degradation, which can result in poor visual quality, laggy screen updates, or reduced responsiveness. Consistently high degradation factors point to network congestion, server resource contention, or suboptimal Thinwire configuration affecting the user experience.

Printer bandwidth input:

Indicates the bandwidth used when this user prints to a desktop printer over the ICA channel.

Kbps

Comparing the values of these measures across users will reveal which user is issuing bandwidth-intensive print commands over the ICA channel.

If bandwidth consumption is too high, you may want to consider disabling printing. Alternatively, you can avoid printing large documents over the ICA connection.

Printer bandwidth output:

Indicates the bandwidth used when the desktop responds to print jobs issued by this user.

Kbps

Session bandwidth input:

Indicates the bandwidth used from this user to the virtual desktop for a session

Kbps

Comparing the values of these measures across users will reveal which user and which virtual desktop is performing bandwidth-intensive operations for a session.

Session bandwidth output:

Indicates the bandwidth used from the virtual desktop to this user for a session.

Kbps

Session compression input:

Indicates the compression ratio used from this user to the virtual desktop for a session.

Number

Compression reduces the size of the data that is transacted over the ICA channel.

Comparing the values of these measures across users will reveal which client has been configured with a very low and a very high compression ratio.

In the event of high bandwidth usage over an ICA channel, you can set a higher compression ratio for the corresponding client and thus reduce bandwidth consumption.

Session compression output:

Indicates the compression ratio used from the virtual desktop to this user for a session.

Number

Frames dropped

Indicates the number of display frames dropped for this user’s session during transmission.

Frames/sec

Dropped frames lead to visual stutter and degraded user experience.

Frames sent

Indicates the total number of display frames sent to this user’s client during the measurement period.

Number

Very low values for this measure may indicate idle or stalled sessions.

Thinwire output/input ratio

Indicates the ratio between output frames sent and input frames received for this user’s session.

Percent

An unusually high ratio may suggest excessive screen redraws or inefficient rendering.

Thinwire input frame rate

Indicates the rate at which input frames generated by this user’s session are sent to the server using the Thinwire protocol.

Frames/sec

An unusually high value can point to excessive input activity or inefficient rendering.

HDX media stream for flash data bandwidth input:

Indicates the bandwidth used from this user to virtual desktop for flash data traffic.

Kbps

Comparing the values of these measures across users will reveal which user has been transmitting/receiving bandwidth-intensive flash data.

HDX media stream for flash data bandwidth output:

Indicates the bandwidth used from the virtual desktop to this user for flash data traffic

Kbps

Thinwire output frame rate

Indicates the rate at which display frames are sent from the server to this user’s client over Thinwire.

Frames/sec

If the value of this measure is low, it may result in choppy screen updates.

Thinwire estimate bandwidth

Indicates the estimated network bandwidth consumed by Thinwire traffic for this user’s session.

Mbps

High bandwidth usage can impact overall network performance and may indicate graphics-intensive workloads.

Session line speed input:

Indicates the average line speed of all the sessions of this user to the desktop.

KB/Sec

Session line speed output:

Indicates the average line speed from the desktop to this user.

KB/Sec

Bandwidth usage of user's session:

Indicates the percentage HDX bandwidth consumption of this user.

Percent

Compare the value of this measure across users to know which user is consuming the maximum HDX bandwidth.

Thinwire bandwidth input:

Indicates the bandwidth used from user client to desktop for ThinWire traffic.

Kbps

Typically, ICA traffic is comprised of many small packets, as well as a some large packets. Large packets are commonly generated for initial session screen paints and printing jobs, whereas the ongoing user session is principally comprised of many small packets. For the most part, these small packets are the highest priority ICA data called Thinwire. Thinwire incorporates mouse movements and keystrokes.

Compare the value of these measures across users to know which user’s keystrokes and mouse movements are generating bandwidth-intensive traffic.

Note:

This measure will report the value 0, if Framehawk is enabled for a user.

Thinwire bandwith output:

Indicates the bandwidth used from desktop to user client for ThinWire traffic.

Kbps

Note:

This measure will report the value 0, if Framehawk is enabled for a user.

Thinwire JPEG image quality

Indicates the JPEG image quality level used to transmit graphics for this user’s session.

Percent

Lower quality may reduce bandwidth usage but degrade visual clarity.

Thinwire latency

Indicates the latency experienced by this user’s session while transmitting display data using Thinwire.

Seconds

High latency can cause visible lag and poor user experience during screen updates.

Resource shares:

Indicates the total number of resource shares used by this user.

Number

By comparing the value of this measure across users, you can identify the user who is hogging the resources.

Frame rate:

Indicates the rate at which frames are processed during this user session.

Frames/Sec

FPS is how fast your graphics card can output individual frames each second. It is the most time-tested and ideal measure of performance of a GPU. Higher the value of this measure, healthier is the GPU.

Framehawk frame rate:

Indicates the rate at which frames are processed by the Framehawk virtual channel, if it is enabled for this user session.

Frames/Sec

The Framehawk virtual channel optimizes the delivery of virtual desktops and applications to users on broadband wireless connections, when high packet loss or congestion occurs.

A high value is desired for this measure, as it indicates faster delivery of applications to users, which in turn makes for a better user experience.

You can compare the value of this measure with that of the Frame rate measure of a user to ascertain whether/not the Framehawk virtual channel has indeed enhanced that user’s experience with virtual desktops. If this comparison reveals that the value of this measure is higher than that of the Frame rate measure, it is a clear indicator of the effectiveness of the Framehawk virtual channel.

Note:

This measure will report the value 0 if Framehawk is not enabled for a user or if the device from which the user is accessing the virtual desktop does not support Framehawk.

Thinwire RTT

Indicates the round-trip time experienced by Thinwire traffic for this user’s session.

Seconds

High RTT values indicate network latency that can negatively impact session responsiveness.

Framehawk latency:

Indicates the latency experienced by this user session when the Framehawk virtual delivery channel is used.

Secs

To judge the effectiveness of Framehawk, compare the value of this measure with that of the Client network latency measure for a Framehawk-enabled user. If the comparison reveals a lower value for this measure, it implies that Framehawk has succeeded in minimizing the latencies over the delivery channel.

Note:

This measure will report the value 0 if Framehawk is not enabled for a user or if the device from which the user is accessing the virtual desktop does not support Framehawk.

Framehawk network loss:

Indicates the percentage of packet loss experienced by this user session when the Framehawk virtual delivery channel is used.

Percent

If the value of this measure is very low, it indicates that Framehawk has been very effective in minimizing the loss of packets that typically occur when data is transmitted or received over a channel.

Note:

This measure will report the value 0 if Framehawk is not enabled for a user or if the device from which the user is accessing the virtual desktop does not support Framehawk.

Client network latency:

Indicates the latency experienced by this user when transmitting/receiving data over the ICA channel.

This measure maps to the 'Network RTT' measure in Citrix Director.

Secs

A low value is a sign of the good health of the ICA channel.

Clipboard bandwidth output

Indicates the bandwidth used for clipboard operations performed such as cut-and-paste, from the ICA session to this user's endpoint.

Kbps

Clipboard bandwidth input

Indicates the bandwidth used when performing clipboard operations such as cut-and-paste, from this user's endpoint to the ICA session.

Kbps

User's connection quality indicator:

Indicates the connectivity of this user with the Citrix environment.

The values that this measure can report and their corresponding numeric values are discussed in the table above:

Measure Value	Numeric Value
Poor connection	1
Weak connection	2
Strong connection	3
None	4

Note:

By default, this measure reports the Measure Values listed in the table above. In the graph of this measure however, the value of this measure is represented using their numeric equivalents only.

By default, Citrix recommends a standard computation of user’s connection quality indicator as mentioned in the table below:

Connection Quality Indicator	How is the Connection Quality Indicator calculated?
Weak	Reported when Bandwidth > 1MBPs Latency <= 150ms ICA RTT <= 180ms
Strong	Reported when Bandwidth > 8 MBPs Latency <= 150ms ICA RTT <= 180ms
None	Reported when Bandwidth <= 0 MBPs Latency < 0 ICA RTT < 0
Poor	Reported when any condition other than the above is noticed.

The detailed diagnosis of this measure reports the bandwidth utilized by each user, the latency, the protocol used to establish the session, client version, client ID, Gateway IP Address, Gateway Country, Gateway region, Gateway city, Citrix cloud infra, etc.