Administering Multicast Options

Multicasting with JGroups

SAS middle-tier applications use JGroups in the Web application server for inter-machine communication between applications and caching of application properties. The JGroups software uses IP multicasting as the protocol for group communications, and binds to a valid IP multicast address and UDP port. Typically, multihomed machines have multiple NIC cards, each with its own address. By default, the JGroups software selects the first non-loopback NIC as its bind address. In some cases, the Web application server selects the value of InetAddress.getLocalHost().getHostName() as the bind address for use by JGroups.

The communication protocol used by JGroups will not function correctly if the value chosen by JGroups for the SAS Remote Services application and the value chosen by the Web application server for the SAS middle-tier applications on a single machine do not match.

Set the following JVM command line option to ensure that the Web application server and the JGroups software use the same bind address:

-Djgroups.bind_addr=ipaddress

Enabling JGroups Communication for Multihomed Machines

If your environment consists of multiple machine installations that include one or more multihomed machines, you must configure the following JVM command line option to ensure that JGroups communication is successful:

-Djgroups.bind_addr=IPAddress

Note: If this JVM command is not configured in environments with multihomed machines, the distribution function in the Report Output Generation tool will not function. [cautionend]

To enable the distribution function in the Report Output Generation tool in environments with multihomed machines, the -Djgroups.bind_addr command should be set in the following locations:

SAS Remote Services. For more information, see Specify Multicast Options for SAS Remote Services.
Web application server. For more information, see Specify Multicast Options for Web Application Servers.
Outputgen.ini file. Add the -Djgroups.bind_addr command to this file to enable the distribution of reports.

On Windows, this file resides in this directory path:

Program Files\SAS\SASBIReportServices\4.3

As an example of how to enable the JGroups communication, consider this scenario where the IP address for the Web application server in the middle tier is 10.12.10.230. The IP address for the server tier is 10.12.10.228. In this case, the command is specified in the RemoteServices.bat file, RemoteServices.SH file, or the wrapper.conf file as follows:

-Djgroups.bind_addr=10.12.10.230

On the Web application server, the following command is added:

-Djgroups.bind_addr=10.12.10.230

In the Outputgen.ini file, the IP address for the server tier is specified:

-Djgroups.bind_addr=10.12.10.228

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