Configuring Session Reliability

Session Reliability keeps sessions active and on the user’s screen when network connectivity is interrupted. Users continue to see the application they are using until network connectivity resumes.

This feature is especially useful for mobile users with wireless connections. Take, for example, a user with a wireless connection who enters a railroad tunnel and momentarily loses connectivity. Ordinarily, the session is disconnected and disappears from the user’s screen, and the user has to reconnect to the disconnected session.

With Session Reliability, the session remains active on the server. To indicate that connectivity is lost, the user’s display freezes and the cursor changes to a spinning hourglass until connectivity resumes on the other side of the tunnel. The user continues to access the display during the interruption and can resume interacting with the application when the network connection is restored. Session Reliability reconnects users without reauthentication prompts.

Users of Program Neighborhood can override the Session Reliability setting by selecting or clearing the Enable session reliability option in their application or connection settings. Users of the Citrix XenApp plugin and the Citrix XenApp Web Plugin cannot override the server setting.

By default, Session Reliability is enabled at the server farm level through the Access Management Console or the Delivery Services Console, depending on the version of XenApp you have installed. You can customize the settings for this feature from the server farm’s Properties page and modifying the Session Reliability settings as appropriate. You can edit the port on which XenApp listens for session reliability traffic and edit the amount of time Session Reliability keeps an interrupted session connected.

The Seconds to keep sessions active option has a default of 180 seconds, or three minutes. Though you can extend the amount of time Session Reliability keeps a session open, this feature is designed to be convenient to the user and it does not, therefore, prompt the user for reauthentication. If you extend the amount of time a session is kept open indiscriminately, chances increase that a user may get distracted and walk away from the client device, potentially leaving the session accessible to unauthorized users. Note: You can use Session Reliability in conjunction with Secure Sockets Layer (SSL). If you do not want users to be able to reconnect to interrupted sessions without having to reauthenticate, use the Auto Client Reconnect feature. You can configure Auto Client Reconnect to prompt users to reauthenticate when reconnecting to interrupted sessions.

If you use both Session Reliability and Auto Client Reconnect, the two features work in sequence. Session Reliability closes, or disconnects, the user session after the amount of time you specify in Seconds to keep sessions active. After that, the settings you configure for Auto Client Reconnect take effect, attempting to reconnect the user to the disconnected session. Important: If the Session Reliability feature is enabled, the default port used for session communication changes from 1494 to 2598.

Configuring ICA Keep-Alive

Enabling the ICA Keep-Alive feature prevents broken connections from being disconnected. When enabled, if XenApp detects no activity (for example, no clock change, no mouse movement, no screen updates), this feature prevents Remote Desktop Services from disconnecting that session. XenApp sends keep-alive packets every few seconds to detect if the session is active. If the session is no longer active, XenApp marks the session as disconnected.

However, the ICA Keep-Alive feature does not work if you are using Session Reliability. Session Reliability has its own mechanisms to handle this issue. Only configure ICA Keep-Alive for connections that do not use Session Reliability.

ICA Keep-Alive settings override keep-alive settings that are configured in Microsoft Windows Group Policy.

Configure the following Citrix Computer policy settings: ICA keep alive timeout. Specifies the interval (1-3600 seconds) used to send ICA keep-alive messages. Do not configure this option if you want your network monitoring software to close inactive connections in environments where broken connections are so infrequent that allowing users to reconnect to sessions is not a concern. The 60 second default interval causes ICA Keep-Alive packets to be sent to client devices every 60 seconds. If a client device does not respond in 60 seconds, the status of the ICA sessions changes to disconnected.

ICA keep alives. Sends or prevents sending ICA keep-alive messages periodically.

More info here: https://docs.citrix.com/en-us/xenapp-and-xendesktop/7-15-ltsr/manage-deployment/sessions.html