An apparatus for transmitting a broadcast signal, the apparatus includes a hardware processor configured to generate input packets carrying service data for a broadcast service; generate a link layer packet having a header and a payload by using the input packets; and generate a broadcast signal including the link layer packet; and a broadcast transmitter configured to transmit the broadcast signal, wherein the header includes a packet type field indicating a packet type of the input packets, and determining which header fields present after the packet type field, wherein when the packet type field indicates that the input packets are Internet Protocol (IP) packets, the hardware processor, to generate a link layer packet, further configured to: add 2 signaling bits immediately after the packet type field, the 2 signaling bits indicating whether the payload carries a segment of one input packet or concatenated input packets.