Control, Transmission, and Synchronization Interfaces
Issue 8.0 July 2002
5-21
OC-48 Point-to-Point Applications 5
Free Running/Free Running Configuration 5
For initial SONET deployment with DS3 low speed interfaces, no external
synchronization reference is needed; therefore, the expense of connecting to one
is eliminated. The free running/free running configuration is ideal for linear
networks with asynchronous interfaces. It allows the FT-2000 OC-48
Add/Drop-Rings Terminal to interface with the existing asynchronous equipment
in a network and enables a smooth evolution to a synchronous network.
The free running/free running configuration applies to OC-48 point-to-point
applications (with or without FT-2000 OC-48 Repeater Bays) with asynchronous
(DS3) low speed interfaces only.
In the free running/free running configuration (Figure 5-10), both terminals are
free running; that is, they require no external synchronization reference. The
transmit and receive signals are asynchronous with respect to each other.
For more information about platform timing modes, refer to "Platform
Synchronization" in this section.
Figure 5-10. Free Running/Free Running Configuration
DS3 DS3
OC-48
Free-Running Free-Running
CO CO
FT-2000FT-2000
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