7.1sp3 PAR fails to route when GT11CLK or GT11CLK_MGT drives DCM. The following message occurs in PAR:
"IMPORTANT MSG: UNROUTABLE DESIGN; CHANGE PLACEMENT or EASE CONSTRAINTS"
When PAR instantiates the macro for DCM and DCM is connected to GT11CLK, PAR fails to route.
This issue has been fixed in 7.1i Service Pack 3.