A transmitting system, a receiving system, and a method of processing a broadcast signal are disclosed herein. The receiving system include a tuner, a demodulator, a block decoder, an RS frame decoder, and a service manager. The tuner receives a broadcast signal. Herein the broadcast signal includes mobile service data, a service map table signaling access information of the mobile service data, and a plurality of known data sequences. The mobile service data and the service map table are packetized to an RS frame. The demodulator demodulates the received broadcast signal. The block decoder turbo-decodes the mobile service data and the service map table included in the demodulated broadcast signal in block units. The RS frame decoder forming an RS frame including the turbo-decoded mobile service data and service map table, performs primary first cyclic redundancy check (CRC)-decoding and RS-decoding, and performs secondary CRC-decoding on the primarily CRC-decoded and RS-decoded RS frame. The service manager acquires source IP address information of IP datagrams of the RS frame-decoded mobile service data from the service map table.