Describe how demand priority works.

Demand priority utilizes a 'hub-centric approach to media access. A 'smart hub' controls access to the network. When a workstation needs to transmit, it sends a request to the hub. The hub grants permission to transmit based on network conditions and requester priority. Because they are under the control of the hub, workstations do not 'compete' for access to the network.

Unlike 'regular' Ethernet in which a transmission is transmitted to all stations, demand priority utilizes a directed transmission. The hub directs the transmission from sender to intended recipient rather than sending it to all stations.

With demand priority, workstations can transmit and receive at the same time. This is because demand priority employs 'quartet signaling' on four pairs of wires. Regular 10BaseT Ethernet transmits over two wire pairs.