A method of transmission of digital information in a digital broadcast system including a central transmission station and one or more decoders, the central station transmitting at least one transport stream comprising a stream of packets encapsulating data tables or sections within their payloads, one or more encapsulated sections including a medium access control (MAC) address used to control the reception of that section by one or more decoders wherein the MAC address is dynamically assigned by the central transmission station and communicated to the or each decoder in an address assignment message using a fixed IP address.