Nortel Networks DCT1900 manual Synchronization Topology, Strap Settings

Technical Product Manual - DCT1900

Installation Instructions, Central Processing Unit (CPU) – REX-BRD0004 or 2/ROFNB 157 19/2

Slave

Slave

Master Slave Slave

Slave	Level 1	Slave
		Level 2

Fig. 5–1 Synchronization Topology

Strap Settings

As the master CPU determines the timing in the star network, it can either generate the frame timing on its own or synchronize it to an external source like a 2 Mbit/s link (DLU or DTU). Synchronizing to a 2 Mbit/s or 1.544Mbit/s link reduces the likelihood of frame slips on the link but is only allowed when the clock stability is better than 2 ppm. In the Master/Stand Alone mode the CPU provides the frame timing on its own. As a Slave/Standalone the CPU receives framing sync from the master RE. In Figure 5–2 an overview of the strap settings is given.

When setting the CPU up as a master or slave, both of the Air Interface master/slave jumpers must be set the same. Refer to Figure 5.2 for the correct configuration.

When the CPU is strapped as a master, the frame timing strap must be set correctly. Refer to Figure 5.2 for the correct configuration.

When the CPU is strapped as a slave, the function of the frame timing strap is disabled and the position of this strap is irrelevant. If the CPU is strapped as a slave then there must be a Sync cable from the Sync Out on the master RE connected to the Sync In connector on the slave.

Refer to Chapters 17 and 19 in Section 5 of the TPM for information on Sync cable connectivity.

5-2	Install-DCT1900/R8/mw
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