The signal RXD_IBUF has no load. PAR will not attempt to route this signal. Your design did not meet timing. The following are some suggestions to assist you to meet timing in your design. Review the timing report using Timing Analyzer (In ISE select "Post-Place & Route Static Timing Report"). Go to the failing constraint(s) and evaluate the failing paths for each constraint. Try the Design Goal and Strategies for Timing Performance(In ISE select Project -> Design Goals & Strategies) to ensure the best options are set in the tools for timing closure. There are 1 loadless signals in this design. This design will cause Bitgen to issue DRC warnings. There are 1 loadless signals in this design. This design will cause Bitgen to issue DRC warnings.