2 Line Unit (LU1)
The timing block has the following main functional elements:
• Temperature compensated SEC/Stratum 3+ oscillator with PLL and holdover logic
• Station clock interface with PLL and framer
• Reference clock selection logic
• Clock monitoring logic
The Network Element Clock is distributed via the backplane to each line unit where the interfaces
supporting synchronization via Synchronous Ethernet may use it as a Tx reference. In the opposite
direction, the recovered line clock can be transferred to the timing block and, depending on the
con
fi
guration, the Network Element Clock is able to use it as a reference. The monitoring logic takes
care that the selected reference clock is valid. It also monitors the operation of both PLL and other
available reference clocks set on the fallback list (contains clock sources/priority order selected by
the user). If all the clock sources fail, the Network Element Clock will enter into holdover mode and
maintain the frequency and phase drift within the speci
fi
ed limits.
The station clock input/output interface is on the front plate of the timing block. Depending on the
user needs, either coaxial or differential cabling can be used with a corresponding connector, i.e.
SMB or RJ-48c. The front panel has also the Time of Day and Pulse Per Second (PPS) interfaces in
an RJ-45 connector. The Time of Day and PPS interfaces use a point-to-point ITU-T V.11 interface.
Fig. 5 8665 Smart Router Timing Front Panel Connectors
The port must be connected to the same type of port with proper cable, otherwise network
element functionality may be affected or physical damage may occur. Long cables should be
terminated properly to reduce interference.
Station Clock Interface Signals of RJ-48c, Female 8 Pins
Pin #
Description
1
Input A-wire (ring)
2
Input B-wire (tip)
3
Not connected
4
Output A-wire (ring)
8600 Smart Routers
76.8670-40128B
8665 Smart Router FP7.0 Reference Manual
© 2015 Coriant.
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