RFC Connection setup in SAP System

RFC(Remote function call) plays a vital role in SAP systems.

Consider you have two systems namely PRD and QAS.
RFC names will be like below
PRD -PRDCLNT100
QAS -QASCLNT200

RFC connection type R/3 ABAP connections
Above naming convention is used by most of the basis administrators <SID>CLNT<Client no#>

So PRD system will use QASCLNT200 RFC connection to communication with QAS system.
Similarly QAS system will use PRDCLNT100 RFC connection to communication with PRD system.

Let us see how to setup RFC connection in PRD to QAS system which means RFC connection is done at PRD system.

1. Login to QAS client 200
2. Go to tcode SU01 and create a username as your wish(consider PRD2QAS)
3. Make sure its a communication user and has valid RFC authorization or you may assign SAP_ALL and SAP_NEW profiles if you're not sure about the roles 
4. Now login to PRD client 100 client
5. Go to SM59 tcode and select ABAP connections
6. Click "Create" button or press F8
7. Enter the RFC connection name(ie.QASCLNT200) and choose connection type as 3 which means ABAP connecions
8. Enter the description of the RFC like "RFC connection for QAS system" and save
9. Now Enter the Target Host as system name(Computer name) of the QAS system or enter the IP address of the system and system number of QAS(like 00)
10. All the above settings must be carried out on "Technical Settings" tab
11. Next go to "Logon & Security" tab
12. Enter the Client number of the QAS system i.e. 200
13. Also enter the username and password which is created in QAS in initial stage(ex.PRD2QAS and pwd: QASED56$%)
14. Language is optional and similarly Unicode option in Unicode tab
15. You can select "Unicode" option if target system is Unicode system or leave it
16. Now save the settings and you will be prompted "Connection will be used for Remote logon"
17. Click "OK" and Click "Connection Test" or Ctrl+F3
18. Similarly you can test Unicode connection 
19. But importantly you need to check Authorization test Menu bar Utilities --->Test ---> Authorization Test or press Ctrl+F4 on your Keyboard
20. All the above test must be successful and you will get result like blow

Action                      Result

Logon                 23 msec

Transfer of 0 KB         3 msec

Transfer of 10 KB 4 msec

Transfer of 20 KB 4 msec

Transfer of 30 KB 5 msec

Now we successfully configured the RFC connection between PRD to QAS system

Similarly repeat the same steps in QAS system to setup RFC connection in QAS(PRDCLNT100) to PRD

Hope this will help you