Using Logon Groups for Load Balancing

Use

Logon groups represent a logical mapping of a set of application server instances in an SAP system to a set of application aliases. They are used by the Web Dispatcher (or another load balancing solution in place) to determine the set of instances available to load balance the request to a given alias.

One logon group can contain multiple application server instances; one instance can participate in one or more logon groups.

Process

There are two ways to configure logon groups for load balancing in an AS Java cluster:

Using SAP NetWeaver Administrator (hence, store configuration in the AS Java database) and SAP Web Dispatcher to retrieve their definition from the AS Java automatically at runtime.

More information: Configuring Logon Groups on AS Java .
Using the icrgroups.txt and urlinfo.txt configuration files, which you place on the file system. AS Java is then configured to find the location of the files and retrieves the logon groups configuration information from them.

More information: Configuring Logon Groups Using Configuration Files .

Recommendation

We recommend that you use the first method. The definition of logon groups is easier when you do it using the user interface of SAP NetWeaver Administrator compared to the complex syntax in the plain text configuration files. In addition, using the first method you get the logon group definition stored in the AS Java database, whereas text files in the second method are stored on the file system.