Illustrations of Loops and Self-Tests

9/24/01 12-9

12.9.6 Receiving DS-1 CSU Loopback12.9.7 Sending DS-1 CSU Loopback

Figure 12-7: Sending DS-1 CSU Loopback

Voice
Channels
V.35
Data
DS-1 Network
Receiving DS-1 CSU Loop
Causes a network/line loopback
Loopup code sent by remote unit or network,
occurs at local DS-1 CSU.
D4 - line loop "Unframed"
ESF AT&T Line/Payload
ESF BOM Line/Loop
DS-1 vendor checks framing/errors
CSU
Loopup Code
Voice
Channels
V.35
Data
DS-1 Network
Send DS-1 CSU Loop
Local unit sends CSU loopup code, loop occurs at remote
CSU. This is a line loop only.
Check for framing/errors at local unit.
Commands:
ds1 1 send line loopup
ds1 send network QRSS
statistics ds1 1 current
ds1 1 send loopdown
CSU Loopup
Code CSU Loopup
Code