A switch can continually display the log messages because the service config command is enabled on the switch.
These error messages usually occur after the switch has performed a Cisco IOS Software upgrade. In the latest Cisco IOS software release, the service config command is the default value. Since this is the default value, the service config command line sometimes does not show up in the show run command output.
These messages are also seen on a Cisco router.
In a scenario where an IPS/IDS is used, you sometimes observe that the router continuously sends tftp broadcast. This is confirmed by the IP address of the source and the destination is 255.255.255.255, traffic is UDP 69 (TFTP).
In order to stop the log messages from being generated and for the problem of broadcast, issue the no service config global configuration command.