363-206-285
Circuit Pack Descriptions
7-104 Issue 3 June 2001
Figure 7-39. 22F/22F-U/22F2-U OLIU Circuit Pack
General Description of Operation 7
The 22F-type OLIUs multiplex three STS-1 signals to an STS-3, inserts the
SONET transport overhead bytes (line and section), and scrambles the resulting
signal. This STS-3 signal drives the laser transmitter to create the OC-3 output.
The received OC-3 signal is converted back to an electrical STS-3. This STS-3 is
descrambled and demultiplexed into three STS-1 signals, and transport/path
overhead is accessed. Some of the overhead (for example, section datacom
channel) is passed via serial data links to the control packs, while other bytes (for
example framing, parity check) are processed on board. The STS-1 signals go
through a pointer processor to guarantee STS-1 frame alignment to the local
system clock before being routed to the other main and function unit slots.
If an incoming STS-1 signal from the fiber is to be VT1.5 cross-connected, VT1.5
pointer-processing is performed on this pack and STS-1 path overhead
termination is performed on these signals. All signals entering this pack from
either the backplane or from the optical interface may be routed as STS-1s. If
appropriate, VT1.5 routings may be established between STS-1s using a VT1.5
cross-connection.
OLIU
x
x
x
x
x
Universal
Optical
Connector
AT& T
AT& T
22F-U
FAU LT
ACTIVE
S1:1
IN
OUT
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