TYPICAL LAYOUT
Figure 6-2 shows a typical layout for a data communications link. Several of the prominent physical layer (L_1) standards do not specify the complete physical interface between to user devices (called Data Terminal Equipment (DTE) in the ITU-T specifications). Specifically, the span between the modems may not be defined. Prominent examples are the EIA-232 and V.24 standards. Fortunately, this part of the physical interface is standardized through the ITU-T V Series modem specifications. Figure 6-2 shows the relationship of these specifications to the physical layer interface.
Figure 6-2. Analog configuration
The cables and wires ...
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