ADTRAN TSU LT User Manual

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Contents

ADTRAN TSU LT User Manual Manual pdf 27 page image

TSU LT User Manual Chapter 1. Introduction61202060L4-1 © 2002 ADTRAN, Inc. 27Self-testThe self-test checks the integrity of the internal operation of the electronic components by performingmemory tests and by sending and verifying data test patterns through all internal interfaces. Althoughactual user data cannot be passed during these tests, the self-test can run with the network and DTEinterfaces in place and without disturbing any external interface.The self-test automatically executes upon power up. It can also be commanded from a front panel menu orfrom the control port.In addition to the specified self-tests, background tests are also run on various parts of the internalelectronics. These run during normal operation to confirm continued correct functioning. The backgroundtests include:• Monitoring the phase-locked loop for lock.• Standard background network performance monitoring, as required by ANSI T1.403 and AT&T 54016for which the results are stored.Loopback TestsA number of different loopbacks can be invoked locally from the front panel, by T-Watch commands, orremotely by using special inband codes. These include AT&T D4 network loop up/loop down codes andV.54 loop up/loop down codes for the Nx56K/64K serial interface. Additionally the loopbacks can beremotely controlled by out-of-band commands via the T1 ESF facility data link (FDL), or from T-Watchvia a modem connection. Network and DTE interface loopbacks are discussed in this section.Network LoopbacksThere are three types of network loopbacks. See Figure 1-5.Line LoopbackLoops all of the received data back toward the network. The transmitted data is the identical line codethat was received, including any bipolar violations or framing errors.Payload LoopbackSimilar to line loopback, except that the framing is extracted from the received data and thenregenerated for the transmitted data.Data LoopbackLoops back all active DS0s and inserts idle code into unoccupied DS0s.Figure 1-5. Network Loopback Tests