A method of processing a broadcast signal in a transmitting system, includes encoding broadcast data for broadcast services; encoding first signaling information providing information for discovery and acquisition of a broadcast service; encoding second signaling information including service entries for the broadcast services, wherein one of the service entries includes a first service identifier for identifying the broadcast service and bootstrap information for discovering a transport session carrying the first signaling information, wherein the bootstrap information includes destination Internet Protocol (IP) address information of the transport session carrying the first signaling information and destination port number information of the transport session carrying the first signaling information; and encoding physical layer signaling information including first physical layer signaling information having a fixed size and second physical layer signaling information having a variable size.