OMS 3250

OMS3250Product DescriptionIn OMS3250, the STM-N/OTM–x.n signal is processed by the Tributary card and passed to theSwitch Unit that provides the connection functionality at the VC-4/ODUk level, routing the trafficto any of the tributary cards.11.2.2 Timing signalsThe distribution of timing signals is shown in Figure 17.EXT1 EXT2Tout (two externalsynch. interfaces)SWITCH ASYSTEM TIMING (SW)Tributary interfacesSTM-1/4/16/64Trib. 1 . . . . .STM-1/4/16/64Trib.32Tributary interfacesTout (two externalsynch. interfaces)SWITCH BSYSTEM TIMING (SW)EXT1 EXT2Figure 17: Distribution of Traffic SignalsIn the OMS3250, two independent external synch source inputs are available. All of the possiblesynchronisation sources extracted from the traffic units go to each of the duplicated SwitchUnits. The actual system timing is derived from the working Switch Unit and is provided to alltraffic cards. Also two external synchronisation outputs (TOUT, i.e. independent 2MHz / 2Mb/ssignals) are derived from the working Switch Unit.11.2.3 Synchronisation Status MessagingThe use of Synchronisation Status Messaging (SSM) method provides an indication of thequality of the timing in order to allow the selection and confirmation of the highest qualitysynchronisation source. The SSM/TM are transported by bits 5:8 of the first S1 byte as definedin Rec. G.707 (see section 9.2.2.11) for STM-N and by bits Sax1: Sax4 (x=4,5,6,7 or 8) of TS0for T3 (external input) and T4 (external output) interfaces as defined in revised Rec. G.704 forG.704 2Mbit/s signal.11.2.4 Control signalsThe control signals are distributed in OMS3250 equipment as shown in Figure 18.Issue 1 Copyright – Refer to Page 2 Page 51 of 74