If the switch fails POST, contact Cisco Systems or your authorized reseller to return the switch. Spanning-tree discovery takes approximately 30 seconds to complete, and no packet forwarding takes place during this time. Diagnosing Problems Use Table 7-1 to identify your problem and resolve it. Note that those problems that refer to high-speed expansion slots and their inserted modules apply only to the EtherSwitch 1420. Configure port for half duplex.
Late collisions mean the port is configured for half duplex and the attached device is full duplex.
Configure the port for full duplex. Cabling Distance Exceeded Port statistics show excessive FCS, late-collision, or alignment errors. Reduce the cable length to within the recommended distances. If attached to a repeater, the total distance between the two end stations exceeds the 100BaseT cabling guidelines. See your 100BaseT repeater documentation for cabling guidelines.