1. The model file of RTCP-net is correct but compilation of the simulator for this net fails with message Error occured. Either the chosen file is corrupted or you do not have tools.jar library in '[JRE path]/lib' folder. or No java compiler found. Use java from jdk, not from jre! - what does it mean?

The model file of RTCP-net is correct but compilation of the simulator for this net fails with message Error occured. Either the chosen file is corrupted or you do not have tools.jar library in '[JRE path]/lib' folder. or No java compiler found. Use java from jdk, not from jre! - what does it mean?

It means that the compiler cannot find the Tools.jar library in your currently set Java directory. The easiest solution is to copy Tools.jar library (usually found in the <JDK>/lib directory) to the <JRE>/lib directory.