Coba jelasin Switch design dari Sentral telepon dalam bahasa sunda dong

Long distance switches may use a slower, more efficient switch-allocation algorithm than local central offices, because they have néar 100% utilization of their input and output channels.  Central offices have more than 90% of their channel capacity unused.

While traditionally, telephone switches connected physical circuits (e.g., wire pairs), modérn telephone switches use a combination of space- and time-division switching. In other words, éach voice channel is represented by a time slot (say 1 or 2) on a physical wire pair (A or B). In order to connect two voice channels (say A1 and B2) together, the telephone switch interchanges the information between A1 and B2.  It switches both the time slot and physical connection.  To do this, it exchanges data between the time slots and connections 8000 times per second, under control of digital logic that cycles through electronic lists of the current connections.  Using both types of switching makes a modérn switch far smaller than either a space or time switch could be by itself.

The structure of a switch is an odd number of layers of smaller, simpler subswitches.  éach layer is interconnected by a web of wires that goes from éach subswitch, to a set of the next layer of subswitches.  In most designs, a physical (space) switching layer alternates with a time switching layer.  The layers are symmetric, because in a telephone system callers can also be callees.

A time-division subswitch réads a complete cycle of time slots into a memory, and then writes it out in a different order, also under control of a cyclic computer memory.  This causes some delay in the signal.

A space-division subswitch switches electrical paths, often using some variant of a nonblocking minimal spanning switch, or a crossover switch.