NBN Passive optical network
The passive optical network uses optical splitters to divide the signal on one optical fibre so it can be distributed to several dozen homes (up to about 100). Each home gets the signals sent to all homes, so encryption has to be used for privacy. Data sent from the homes is sent with a multiple access protocol,, with each sharing some of the fibre capacity.
It is not clear from the planning documents, but hopefully multicasting will be supported by the passive part of the network. That is for sending the same data to many people, for example for digital TV, the one optical signal will be sent to all houses, rather than sending multiple copies of the same thing to each house.