ransmit. If the channel in question is free, transmission proceeds; if it is not free, the terminal has to wait until it becomes free. A computer can build up a queue of contention requests; this queue can be organized in a prearranged sequence or in the sequence in which requests are made. control character A character inserted into a data stream for signaling the receiving station to perform a function to identify the structure of the message. Newer protocols use bit-oriented control procedures. control network A type of HAN network for home automation and control that is typically a low-speed powerline network. Control networks have relatively low cost and simple implemen- tation, but they are not designed to support real-time, high-bandwidth, or mobility requirements. control plane An operational part of a network, including infrastructure and distributed intelligence, that executes various signaling, routing, and other control protocols (e.g., OSPF, RIP, RSVP). The control plane protocols exchange data with their peers and generate control information such as routing tables that is needed to forward data packets. Additional functions include managing user interfaces and monitoring system status and health. control station The station in a point-to-point or multipoint network that controls the send- ing and receiving of data. This station can poll or address tributary stations. control unit Circuitry or a device used to coordinate and control the operation of one or more I/O or storage devices and to synchronize the operation of such devices with the operation of the computer system as a whole. controlled access unit controlled access unit A managed MAU or a managed multiport siring hub for token-ring networks. convergence The trend for multiple network technologies and products to come together to form one network with the advantages of all the technologies and products, reducing costs and simplifying operations, administration, and management. In telecommunications, conver- gence can refer to network infras