I have two Catalyst 3524-PWR-XL switches and purchased some twisted pair GBICs (Prolabs) and connected them together via a Cat 6 certified cross over cable. I can get no link and the ports are enabled with auto everything. Even plugging in a server with a gigabit port with a Cat6 straight through cable also resulting in no link. The switches are running IOS 12.0(5.3)WC(1), MAINTENANCE INTERIM SOFTWARE. Is it because I'm not using genuine Cisco parts or am I making some big mistake somewhere? Help would be much appreciated.