DOCSIS is a Data Over Cable Service Interface Specification. DOCSIS protocol will let your Internet service provider provide you internet services through the modem’s coaxial cable. With this protocol, your modem can provide a broadband internet connection. There are different versions such as DOCSIS 2.0 / 3.0 / 3.1, with 3.1 being the most recent version and 3.0 is the most commonly used one.