The function
RFC_HANDLE SAP_API RfcConnect(char * system_name,
char * ms_hostname,
char * group_name,
char * client,
char * user,
char * password,
char * language,
int trace,
RFC_HOSTNAME as_hostname,
int * sysnr);
opens an RFC connection via LOAD BALANCING.
With this function the RFC library will try to connect to an application server with the least load (LOAD BALANCING principle) within a group of predefined application servers.

This function is only available for R/3 Release 3.0 onwards.
Better use the call
This function has the following advantages:
Information about the SAP gateway, application server, system number, etc. as parameters for
RfcOpen or RfcOpenExt or as parameters in sideinfo are no longer necessary. Even the sideinfo is no longer required.
You ought to use
This function is defined in SAPRFC.H.
Return Value:
Function Parameters:
name of the R/3 System
host name of the message server
name of a specific group of application servers
signon data: client
signon data: user-ID
signon data: password
signon data: language
trace /0/1)
name of the connected application server (output parameter)
system number of the connected R/3 System (output parameter)
See also RfcOpen, RFC_OPTIONS, RfcOpenExtV3 and RFC_OPTIONS.