ADTRAN 4200659L1 - Manual (Page 130)

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.