Unit 7 Assignment 1
Switched circuit- A circuit created by the phone company in reaction to signaling (the user tapping telephone keys or a modem sending in the same digits), with the telco tearing down the circuit when the user is finished. Dedicated circuit- An electrical circuit created by a telco on behalf of a customer, with the circuit staying up all the time, dedicated for use by the one customer that ordered the circuit. Also known as a leased line, leased circuit, and point-to-point line. Circuit switching- The overall process by which a series of telco devices called circuit switches connect a circuit from one customer device to the other, with the device’s logic taking incoming bits on one segment in the link and forwarding those bits out the matching outgoing segment, without storing the bits. Packet switching- The process of forwarding customer data in a WAN by looking at the header of the messages sent into the WAN by the customer and making a per-message (per-packet) decision as to where to forward each message. Leased line- A physical link between two locations, provided by a telco, that allows two-way communication between sites. Because the customer does not own the physical line between sites, but rather pays a monthly fee for the service, it is called a leased service or leased line. Also known as a dedicated circuit, leased circuit, and point-to-point line. Time-division- A type of logic used by some networking devices, including circuit switches in the telco, in which the switch divides a faster-speed line into time channels. The TDM logic takes the bits off slower-speed lines and forwards those bits inside the time channels in the higher-speed line (multiplexing), and when receiving bits on a higher-speed line, finds the bits in each time channel and splits those back out to the correct slower-speed line (demultiplexing). Multiplexing- he opposite of demultiplex. For a multiplexer, the process of taking multiple...
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