T9000
Preliminary Data Sheet
November 2000
ISDN Network Termination Node (NTN) Device
10 GCI+ Interface Module (continued)
10.6 GCI+ Loopbacks
DFR (G_L_LBK) and DFR (G_R_LBK) register bits control the loopback mode of the GCI interface.
When the DFR (G_L_LBK) register bit is set, downstream B1/B2 channel is fed back to the upstream B1/B2
channel.
When the DFR (G_R_LBK) register bit is set, upstream B1/B2 channel is fed back to the downstream B1/B2
channel.
Both loopbacks may be set at the same time. Loopbacks are transparent, except in the case when both are active
at the same time. Note that loopbacks only operate over data channels; no other channels will be looped back.
GDRIVER
DD_OE
DD_I
0
DD
0
1
1
LOCAL LOOPBACK
REMOTE LOOPBACK
DU
0
DU_I
1
1
0
G_L_LBK
DATA CHANNEL
G_R_LBK
5-6724 (F)
Figure 19. GCI Loopback Logic
78
Lucent Technologies Inc.
AGERE [ AGERE SYSTEMS ]
