ADC ETU-751C - Manual (Page 26)

Functional Description 700-701-100-02
16 August 9, 2002 UTU-701 and ETU-751 List 1
Unstructured Mode
When 32 time slots are selected, the line and desktop units automatically operate in the unstructured mode (see
“G.704 Framing and Rate Selectable HDSL” on page 17 ). There is no unstructured menu selection.
In the unstructured mode:
• There is no G.704 framing.
• Time slot 0 is the beginning time slot, and the data rate is fixed at 2048 kbps.
• A transparent transmission channel is provided between the local and remote units.
• CRC-4 detection and generation are not available, and E1 alarms are limited.
Any framing, multiframing, and common-channel signals can be transmitted through the HDSL line units in the
unstructured mode, but the units do not monitor for a loss of framing condition.
Table 8 lists system settings for 2048 kbps transport of data between a DTE connected to an UTU-701C and a
DTE connected to an ETU-751C. The settings in Table 8 use the G.703 signal from the UTU-side DTE as the
primary timing source. Timing at the ETU side is recovered from the received G.703 signal. This application is
illustrated in
Figure 7 .
Figure 7. Unstructured Mode Application
Table 8. Typical Unstructured Mode System Settings
Options Setting
Application Mode 32 TS (Unstructured)
UTU-701C (LTU) Interface
Primary Timing Source G.703
G. 703 Port
CRC Mode N/A
Idle Code FF
Data Rate/# of TSs 2048 / 32 TSs
Beginning TS 0
ETU-751C (NTU) Interface
Primary Timing Source G.703
Data Rate / # of TSs 2048 / 32 TSs
Beginning TS 0
Network Side Customer Side
Exchange
Office
DTE
HDSL
Single Pair
HDSL loop
UTU-701
(LTU)
ETU-751
(NTU)
G.703
HDSL
Customer
DTE
G.703
32
Time Slots
(2048 kbps) (2048 kbps) (2048 kbps)
32
Time Slots
32
Time Slots