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MX2800 STS-1 User Manual
Line Loopback
Line Loopback, illustrated in
just prior to the HDB3/B8ZS decoder of the LIU; therefore, any coding violations received by the STS-1
will be inserted back into the network without modification.
If a Line Loopback is active when the MX2800 STS-1 is operating in the
Free-Run timing mode, the timing source for the STS-1 is effectively
removed from the circuit. Therefore, it is up to the test equipment or
network to provide STS-1 timing into the circuit for the duration of the
test.
STS-1
LIU
Analog Loopback
An Analog Loopback
(Figure
this test is a loopback of all VT/Ports after passing through the STS-1 mapper and the LIU. The incoming
STS-1 data is ignored and the outgoing STS-1 stream is looped back into the "AGC/Receive Equalizer
Block" in the LIU.
STS-1
LIU
61204659L1-1A
Figure
6-11, performs a loopback of the entire STS-1. This loopback occurs
NOTE
STS-1
MAPPER
Figure 6-11. STS-1 Line Loopback
6-12) loops the entire STS-1 back to the local loop side. The end effect of
STS-1
MAPPER
Figure 6-12. STS-1 Analog Loopback
CODEC
T1/E1 LIU
(1 of 28)
(1 of 28)
T1/E1 LIU
CODEC
(28 of 28)
(28 of 28)
CODEC
T1/E1 LIU
(1 of 28)
(1 of 28)
CODEC
T1/E1 LIU
(28 of 28)
(28 of 28)
Loopbacks, Section 6
STS-1 Loopbacks
6-9
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