doc.FAQ.CannotStartBroker OpenLink 's Request Brokers are listening services. OpenLink 's 4.x and newer Brokers listen on the TCP port that is passed to the Listen parameter. The Listen parameter appears in the Protocol TCP section of the Session Rules Book. OpenLink 's 3.x and 1.x Brokers listen on PortLow . PortLow appears in the Protocol TCP section of the Session Rules Book. OpenLink 's Request Brokers also use UDP port 60001 to broadcast license information.Use the following guidelines to troubleshoot Broker startup issues:Ensure that OpenLink 's Request Broker is installed. Ensure that Unix Request Brokers are executable. Run oplrqb -? from the /bin sub-directory of the OpenLink server components installation. Ensure that the Request Broker returns version and usage information. Troubleshoot errors, as required. Run uname -a on Unix servers. Compare the Broker's platform of compilation with the platform identified with uname -a. Ensure that the platform of compilation is compatible with the platform returned by uname -a. Install more suitable builds, as appropriate. Open the Session Rules Book and identify the Broker listening port. Run netstat -an, or an equivalent network utility, to check for existing activity on the Broker's listening port. Reassign a free port, or wait for previous listeners to be cleared (up to 2 minutes) as required. Obtain operating system patch information. Some patches may interfere with the Broker's ability to run.