Network Management Specification section 10.4.2 UDP Sessions states the following:

When opening a session via TCP, the Session Initiate response shall be from the same server port as receiving
the request.

However, for UDP sessions, it is advantageous for the server to move the session to an unused ephemeral port.
The server signals this requirement to the client by responding to the Session Initiate using the port selected by
the server. Clients initiating an UDP session must send all subsequent session communications via the port
receiving the Session Initiate response from the server.

To allow the HTS client to connect to a different ephemeral port the following command line option and flag must be added to the hipcfg.txt file located in the home folder:


As an example the hipcfg.txt would be changed from:

-i UDP -a



After modifying and saving the file reboot the HTS.

NOTE: Server's that implement their UDP sessions this way may not be able to pass HIP401 via UDP. If you are having trouble passing this test please file a support ticket with the test case log file and a communication data capture.