Cisco ASR 5000 Series, Installation Manual

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Cabling the Switch Processor Input/Output Line Card
Connecting to a BITS Timing Source ▀
ASR 5000 Installation Guide ▄
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Connecting to a BITS Timing Source
The SPIO can be optionally equipped with a BITS interface that derives a 1544 kHz (SONET T1 framing) or 2048 kHz
(SDH E1 framing) clock signal from an external Building Integrated Timing Supply to synchronize line card timing.
The BITS source derives its timing from a primary reference source (PRS), such as a Stratum 1 clock or Global
Positioning System (GPS) signal.
Connection to the BITS is via a BNC coaxial cable (E1) or 3-pin wire-wrap connector (T1).
Important:
External BITS timing is an alternative to using clock signals derived from an ATM port on an OLC2,
or an ANSI SONET STS-3/SDH STM-1 port on a CLC2. (Line-derived clocking requires that the SPIO be equipped
with the optional Stratum 3 clock module.) For additional information, refer to the
ATM Port Configuration Mode
Commands and Channelized Port Configuration Mode Commands chapters of the Command Line Interface Reference .
Important:
Always refer to the interface and signaling specifications in the OEM documentation supplied with
the BITS source. Your NOC may also have detailed specifications for distributing the BITS clock signals to network
devices such as the ASR 5000.
BITS E1 BNC Interface
The BNC version of the SPIO employs a 75-ohm coaxial BNC connector that accepts an analog E1 BITS signal. The
following figure shows the BITS BNC timing interface.
Figure 36. SPIO E1 BITS BNC Pinout
Use 75-ohm coaxial cable (RG-59/U) between the BITS and the SPIO BNC interface to carry the E1 signal.At the
SPIO, terminate the cable with a 75-ohm BNC male connector.