The %IP-3-LOOPPAK: Looping packet detected and dropped error message is received because of a looping packet that has been detected.

A common cause is a misconfiguration of an IP helper address. The helper address should be the same address as that of the server of the intended service. Putting the address of the router in the helper address causes a routing loop to be created. 

The recommended action is to analyze the source and destination address of the looped packets and verify that the configuration of the IP helper addresses in the router correctly points to the right device and does not point to the local router itself.