It is becoming more common that the switch has port security turned on. This means only one MAC can plug into any single port. It is not a big deal to reset it, but for some reason I could not find a direct answer. Here is mine;
Reset sticky bit
Examples;
- show port-security
- sh interface status err-disabled
- clear port-security sticky int fa 0/1
- clear port-security sticky int Gi1/0/15
References;
- https://community.cisco.com/t5/switching/unable-to-clear-port-security-sticky/td-p/1090926
- https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst4500/12-2/25ew/configuration/guide/conf/port_sec.html
- https://community.cisco.com/t5/switching/view-port-security-disabled-port/td-p/1874794