PairGain 150-1143-03, Manual, Page: 17 / 48

150-451-103-02, Revision 02 Functional Description
HDU-451 List 3 September 18, 1998 9
L
OOPBACK
D
ESIGN
D
ESCRIPTION
Figure 4 on page 9 shows the complete family of loopbacks that a HiGain
system can execute. Four of these loopbacks (NDU1, NDU2, CDU1, and
CDU2) occur in the doubler. These loopbacks can be initiated from the HLU
maintenance port, the HLU front panel push-button, and from a family of
Special Loopback (SPLP) in-band loopback commands.
Figure 4 lists the
Generic, SPLP, in-band loop-up command set for the four doubler loopbacks:
110000 (2 in 6) for NDU1, 111000 (3 in 6) for NDU2, 111100 (4 in 6) for
CDU1 and 111110 (5 in 6) for CDU2. Refer to the appropriate HLU practice
for more details regarding the other doubler loopback commands.
Figure 4. HiGain Loopbacks.
DSX-1
CI
DS-1
Loopbacks
toward
customer
Loopbacks
toward
network
HDSL SPAN
HLU
NLOC
AIS**
AIS
AIS
AIS
AIS
AIS
AIS
AIS
SMJK*
TLOS
NREM
CLOC
HRU
HRU
HRU
HRU
HRU
HDSL SPAN
HDSL SPAN
SPAN 1
SPAN 1
SPAN 2
SPAN 2
SPAN 3
SPAN 3
HDSL SPAN
HDSL SPAN
HDSL SPAN
HLU
HLU
HLU
CREM
ELU
ELU
ELU
ELU
2 in 5
3 in 7
4 in 7
6 in 7
6 in 7
4 in 6 5 in 6
2 in 6 3 in 6
LOGIC
NDU1
CDU1
NDU2
CDU2
HDU HDU
HDU HDU
HLU
HLU
HLU
HLU
HRU
HRU
HRU