As system administrator you want to maintain the message server port number in sapmsg.ini file (instead of in the service file) for load balancing logon in SAP Logon (Pad).
If you use Active Directory (LDAP), please see note 608781.
Up to now the port number for a message server is usually maintained in the service file under etc/service.
It is also possible to maintain this in the file sapmsg.ini as follows:
Adding a new section
[Message Server Port]
Adding the port number mappint under this new section with the following syntax:
SID=PortNumber
like
S01=3901
S01=3902
...
Distribute sapmsg.ini as usual to your users
After your user restart SAP Logon (Pad), they can add new entries or make variable logon for load balancing (Group-Selection).