Introduction1-53610-A2-GB91-90 July 1999Single-Port Async/Sync SupportThe Single-Port Async/Sync feature is used to provideITU-T V.14 asynchronous-to-synchronous dataconversion capability for the DTE ports. The DSUs ateach end of the circuit must be installed with this option.When used with the Time Division Multiplexer (TDM)option, the unit can be configured as a central-site bridgeto provide multipoint partial backup for the circuit.The asynchronous port speeds will always be the sameas the synchronous port speeds when operating at primaryDSU rates, so the port speeds of 150, 300, 600, and1800 bps can only be achieved through oversampling. Tooversample, the Async→Sync configuration option mustbe disabled and the synchronous port rate must be set to arate greater than or equal to four times the asynchronousDTE rate. For example, select 1.2 kbps for thesynchronous port speed if the asynchronous port speed ifthe asynchronous port speed is 150 or 300 bps, select2.4 kbps if it is 600 bps, and 7.2 bps if it is 1800 bps. Thisensures that oversampling will take place.Point-to-Point ConfigurationWhen operating with the Async→Sync configurationoption enabled, a single-port point-to-point circuit canoperate using nondisruptive diagnostics. The controlDSU’s port speed and the tributary DTE port speeds mustbe set to the same rate. Figure 1-1 shows thisconfiguration. Note that the tributary DSUs are configuredas a single port-sharing group.Figure 1-1. Single-Port Point-to-Point Circuit with Nondisruptive Diagnostics
