Syslog reports host 0054.3962.7651 in VLAN 14 flapping between Gi1/0/1 and Gi1/0/2. What is causing the problem?

A host flapping between two ports, especially when those ports are on the same switch and in the same VLAN, is a classic symptom of an invalid or misconfigured port channel (EtherChannel or Link Aggregation Group). When a device expects to send traffic over a logical bundle of links but the switch ports are not correctly bundled, the MAC address of the host can be learned on one physical link, then on the other, causing continuous MAC address table updates and syslog messages indicating "flapping." Undesirable load-balancing configuration might affect traffic distribution but wouldn't typically cause MAC address flapping between ports. A wrong SFP+ or cable would likely result in a link down or errors, not flapping. A failed NIC on the server would cause the server to lose connectivity, not flap between switch ports.