e signals when the trunks associated with outgoing trunk calls are not equipped to receive tone signals. Auxiliary dial pulse conversion equipment is not necessary. topology The connectivity among a group of nodes. Physical topology relates to how devices are cabled. Logical topology refers to how nodes actually interact. trace packet In packet switching, a packet that functions as a normal packet but causes a report of each stage of its process to be sent to the network control center. traffic (1) Messages sent and received over a communications channel. (2) A quantitative measurement of the total messages and their length, expressed in 100 call seconds or other units. traffic flow A measure of the density of traffic. transaction An item of business (e.g., the handling of customer orders and billing). transaction processing (1) In batch or remote batch processing, the processing of a job or job step. (2) In interactive processing, an exchange between a terminal and another device that does a particular action (e.g., entering a customer's deposit and updating the customer's balance). transceiver A device that connects a host interface to a LAN. transducer A device for converting signals from one form to another, such as a microphone or a receiver. transfer rate The speed at which information can be sent across a bus or communications link. translational bridge A bridge that may connect two different MAC layers (e.g., 802.3 and FDDI). transmission Information that is sent in the form of electrical signals over electric wires, waveguides, or radio. transmission line A connection over which communications devices communicate. There are five main types of transmission lines: circuits, channels, lines, trunks, and virtual circuits. transmission medium A physical pathway that connects computers, other devices, and people on a network. Transmission media can be either wireline (e.g., twisted-pair, fiber, coax) or wireless (e.g., microwave, satellite, infrared). transmission speed The rate at which information is passed 