AT&T 7500 series, 7100 series, 2500 series, 7200 series, 7400 series manual Statistical Multiplexing

1-34MULTIPLEXED COMMUNICATION

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Note that the Digital Access and Cross-Connect System (DACS) takes input multiplexed up to the DS1 level. Therefore, communications multiplexed above this level must be demultiplexed before they can be processed by the central office.

STATISTICAL MULTIPLEXING

Statistical multiplexers assign a high-speed (56- or 64-kbps) channel for utilization by several lower-speed (subrate data) devices. Statistical multiplexers do not require signal modulation or switching. The most common configuration places a multiplexer on one end (putting the inputs from multiple devices onto a single line) connected by a direct line to a demultiplexer on the other (sending the channels from processing at different devices or computer ports). (See figure 1-11.)The signal can be switched through a System 75, System 85, or DEFINITY communications system, however, if it is channeled over a dedicated switch or permanent switch connection in the switch and it travels through an modular processor data module (MPDM) upon entering and exiting the switch.

HOST
B
718
		718
719	719	718
	PRIVATE
	LINE
HOST		718
A
718

Figure 1-11.Statistical Multiplexing

Currently, the 718 Stat Mux and the 719 Networker are recommended for use in statistical multiplexing applications. The 719 Networker functions as network node, while the 718 is the DCE at the terminal or host site. Both the 718 and 719 use byte interleaving.