Explaining ICA Session Reliability, Common Gateway Protocol, on TCP Port 2598

A MetaFrame Presentation Server Client, configured to use Session Reliability, establishes an ICA session on TCP port 2598 (instead of port 1494) when connecting to Presentation Server.

Note: When an earlier version of the Client (earlier than Version 7.x) connects to a MetaFrame Presentation Server enabled with Session Reliability, port 1494 is used for ICA sessions.

For more information about session reliability, see:

• Citrix Documentation -?? Session management

• Citrix Documentation -?? Configure Session Reliability

From the Management Console Help:

Port number (default 2598): Assign the port on which you want the servers in the farm to listen for attempts to re-establish dropped connections.

When session reliability is enabled, the ICA Client tunnels its ICA traffic inside the Common Gateway Protocol and sends the traffic to port 2598. The XTE service acts as a relay, removing the Common Gateway Protocol layer and then forwarding traffic to the ICA listener on port 1494:

Likewise, the Presentation Server sends ICA data to the client by way of the XTE service. If the Common Gateway Protocol connection between the client and the XTE service is broken, the ICA listener can continue to send ICA traffic to the XTE service, where it will be buffered until the client reconnects. The user session does not go into a disconnected state as long as the XTE service is buffering data for the user.

On the client, the user application appears frozen while the client attempts to rebuild the Common Gateway Protocol connection. Once the connection is restored, the XTE service flushes the buffered ICA data to the client and the session continues.

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This can be resolved by disabling the Session reliability. Complete the following procedures to disable from Server and from Program Neighborhood Client.

From the Server

Click the Server Farm node and in the right panel, under Session Reliability, select Disable.

From the Program Neighborhood Client

In an Application Set:

1. From the File menu, choose Application Set Settings.

2. From the Application Set Settings windows, click the Default Options tab and clear Enable Session Reliability.

In a Custom ICA Connection:

1. Select the Custom ICA Connection.

2. From the File menu, choose Properties.

3. From the Properties window, click the Options tab and clear Enable Session Reliability.

Note: This?? is applicable to CPS 3.0

Session reliability is enabled by default on the installation of Presentation Server 4.5 and later versions. Note that on XenApp 6.0 and above, this is controlled via Citrix policies.

• See?? Internet Assigned Numbered Authority (IANA)?? for the ports registered by Citrix.
• CTX107902 –?? Session Reliability and Maximum Number of Connections
• CTX104907 –?? Restarting the IMA Service Disconnects Session Reliability Users
• CTX108439 –?? How to Disable Session Reliability through Web Interface
• CTX106531 –?? Troubleshooting the Citrix XTE Service and Errors: There is no route to the specified address ... Protocol Driver Error