Data Communications Networking Devices - 4th Ed.pdf

78 _______________________________ FUNDAMENTAL WIDE AREA NETWORKING CONCEPTSFigure 1.38The D connectorFigure 1.39The V.35 M series connectorFigure 1.38. A cable containing up to 25 individual conductors is fastened to thenarrow part of the connector,while the individual conductors are soldered toprede®ned pin connections inside the connector.ITU X.20 and X.21 compatible equipment use a 15-position subminiature Dconnector that is both smaller and has 10 fewer prede®ned pins than the 25-position D connector illustrated in Figure 1.38. ITU V.35 compatible equipmentuses a 34-position `M' series connector similar to the connector illustrated inFigure 1.39. RS-449 compatible equipment uses a 37-position D connector andmay optionally use a 9-position D connector,while RS-366 compatible equipmentuses a 25-position D connector similar to the connector illustrated in Figure 1.38.Although the HSSI connector has 50 pins,it is actually smaller than the 32-position V.35 connector. Another interesting feature of HSSI connectors is their`genders'. The cable connectors are speci®ed as male,while both DTE and DCEconnectors are speci®ed as receptacles. This speci®cation minimizes the need for