IDSL/DDS Trouble Code
The IDSL/DDS system provides a quick diagnosis in the case of a circuit condition where continuity is broken when the IDSL/DDS circuit uses ADTRAN U- BR1TEs with DDS Loopback capability in the central office or remote terminal. The trouble code type received by a tester determines whether the open condition is occurring on the local loop or at the customer premises. In the event of a 2-wire DSL loss of signal, loss of sync, or open condition caused by an open conductor or disconnected 2-wire loop, the U-BR1TE transmits a Mux-Out-of-Sync (MOS 9Ah) trouble code into the network as shown in Figure 4. During a similar out-of-service condition at the
customer pr mises, the IDSL OCU-R transmits Abnormal Station Code (ASC 9Eh) upstream into the network as shown in Figure 4.
ChannelBankOpen2-wireLoop | CustomerPremises |
MOS9Ah | U | | | | |
B | | OCU-R | | DSU |
RT1 | | |
ChannelEBank | | CusOpentome4-WirerPremisesCustomer |
ASC9Eh | U | ASC9Eh | | Interface | |
B | OCU-R | | DSU |
RET1 | | |
Figure 4. IDSL/DDS Trouble Codes
Loopback LED Operation
IDSL OCU-R loopback status is indicated via the faceplate NTWK LBK and CUST LBK LEDs. An active loopback occurring at the unit being viewed is always indicated via a solid loopback LED. A flashing loopback LED indicates a loopback condition at the far end unit. When a loopback towards the network is initiated, the NTWK LBK LED on the faceplate of the IDSL OCU-R is illuminated. A loopback generated towards the customer illuminates the CUST LBK LED.
ADTRAN U-BR1TE Bidirectional Loopback
The ADTRAN U-BR1TE will execute a bidirectional loopback when performing DS0 DP loopbacks. Refer to Figure 5 for an illustration of the bidirectional loopback.
ADTRAN | |
U-BR1TE | IDSL OCU-R |
| Test |
| Set |
| Bidirectional |
| loopback |
Figure 5. ADTRAN U-BR1TE Bidirectional
Loopback
Remote End Initiated LBK Tests
The U-BR1TE supports loopbacks generated from the IDSL OCU-R which allow testing to be performed without coordination with the CO or test center. Loopbacks initiated by the IDSL OCU-R front panel LBK pushbutton (SW2) aid in system turn-up testing or troubleshooting from the remote end.
The U-BR1TE responds to a loopback command initiated at the IDSL OCU-R as follows:
Pressing the LBK pushbutton on the OCU-R once will initiate a loopback at the U-BR1TE towards the customer. See Figure 6. This allows data to be sent from the remote end to test the local loop and the IDSL OCU-R. This loopback is indicated by a flashing CUST LBK LED on the IDSL OCU-R and a flashing TEST LED (D4) on the U-BR1TE.
Pressing the OCU-R LBK pushbutton a second time initiates a loopback at the IDSL OCU-R towards the 4-wire DDS (CPE) interface. A solid CUST LBK on the IDSL OCU-R indicates a loopback at the IDSL OCU-R towards the customer equipment.
See Figure 7.
Pressing the OCU-R LBK pushbutton a third time disables all current loopbacks initiated by the OCU-R LBK pushbutton.
If errors exist the loopbacks can help determine the source; either the local loop or the IDSL OCU-R. During a remote end initiated loopback the IDSL/DDS system transmits ASC 9Eh towards the network, indicating an out-of-service condition generated by the remote end, as shown in Figures 6 and 7.
All latching loopbacks, whether initiated by the craft interface, LBK pushbutton, CO, or from a remote test center, can be released by sending 35 DDS loop down TIP bytes <X0111010> (where X is a “don’t care” bit).
