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Chapter 6. Diagnostics
6-8 MX2800 STS-1 User Manual 61200659L1-1
STS-1 LOOPBACKS
After you select
STS-1 L
OOPBACK
, the menu in Figure 6-10
appears. The sections following the figure provide descriptions and
illustrations of the testing options. Select
1=D
ATA
M
ODE
to end a
test in progress.
Figure 6-10. STS-1 Diagnostics Menu
Line Network
L
INE
N
ETWORK
performs a loop of the STS-1 back to the network.
This loopback occurs 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. See Figure
6-11 on page 6-9 for an illustration of this text.
If a
L
INE
N
ETWORK
loopback is active when the MX2800 STS-1 is
operating in the
F
REE
-R
UN
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.