Add commnets on user_specified_port.

core/federated/RTI/rti_remote.c

@@ -1583,6 +1583,23 @@ void initialize_RTI(rti_remote_t* rti) {
   rti_remote->num_feds_proposed_start = 0;
   rti_remote->all_federates_exited = false;
   rti_remote->federation_id = "Unidentified Federation";
+  // The federate and RTI both initialize the user_specified_port as 0. For the RTI, when the user_specified_port is 0,
+  // it recognizes that there was no user input to assign a port and assigns the port to the DEFAULT_PORT, which is
+  // 15045.
+
+  // For the federate, when the user_specified_port is 0, it also recognizes that there was no user input and makes the
+  // OS assign the port.
+
+  // The create_TCP_server gets this input argument port, which is actually the user_specified_port for both RTI and
+  // federate. To distinguish whether the RTI or federate is calling this function, I changed the initial value of the
+  // RTI's port as 1.
+
+  // We need to distinguish whether the RTI or federate called the create_TCP_server function for two reasons.
+
+  // First, we should set the default port, which RTI and federate differ.
+  // Next, RTI increments the port number starting from 15045, when the port binding fails. However, the federate does
+  // not increment the port number and try binding.
+  // For more info, check this pr. https://github.com/lf-lang/reactor-c/pull/505
   rti_remote->user_specified_port = 1;
   rti_remote->final_port_TCP = 0;
   rti_remote->socket_descriptor_TCP = -1;