COMSPHERE 3600 Series Data Service Units4-20 July 1999 3610-A2-GB41-70• Case 5 – Aggregate Switched Backup for TDMCircuits ( Figure 4-15 ). A point-to-point TDMcircuit can be backed up using the aggregate switchcapability of the DSU. This may be useful if theDBMs are shared via an external switch.In this example, the control DSU should beconfigured so that AggrSwitch ( Aggregate Switch)is enabled and AgSw Timing ( Aggregate SwitchTiming) is set to Aggr. The DBM-S connected tothe aggregate switch port must have Diag Type( Diagnostic Type) set to None or Disr.The DSU will take its timing from the Switched 56DBM when in Dial Backup mode. The DBM-Sshould be commanded to dial the remote DBMusing the Dial command, and to activate the dataover the backup line using the switch to Dial(→Dial) command.The DSU should then be commanded to switch datato the backup port using the Backup ( Bkup)command. When this is done, the DSU willtransmit the aggregate data stream (including data,framing, and diagnostics) through the aggregateport. To terminate dial backup, send a DrBUcommand to the DBM-S and the DSU.NOTEDuring full backup switching (foraggregate versions only),diagnostic commands arerouted over the aggregate portto the remote DSU or DBM.Only two tests are available totest the DDS facility: Digital Test(DT) and Bit Error Rate Test(BERT).Figure 4-15. Case 5 – Aggregate Switched Backup for TDM Circuits Configuration
