700-701-100-02Functional Description
Table 7. Typical Structured Mode System Settings
Options | Setting |
| |
Application Mode | <32 TS (Structured) |
| |
| LTU Interface |
| |
Primary Timing Source | G.703 |
G.703 Port | |
CRC-4 Mode | Enabled |
Idle Code | FF |
Data Rate / # of TSs | 1536 kbps / 24 |
Beginning TS | 1 |
| |
| NTU Interface |
| |
Primary Timing Source | G.703 |
G.703 Port | |
CRC-4 Mode | Enabled |
Idle Code | FF |
Data Rate / # of TSs | 1536 kbps / 24 |
Beginning TS | 1 |
| |
For applications requiring fractional use of the G.703 port, embedded generation and detection of CRC-4 information, and A-bit insertion, select less than 32 time slots to invoke the structured mode. In the structured mode time slot 0 is regenerated according to G.704 at the output of the G.703 interface port. The following values apply:
•The Sa bits are always set to 1.
•The A bit is normally set to 0 at the G.703 output port. It is set to 1 during an active Loss of Signal (LOS), Alarm Indicating Signal (AIS), or a Loss of Frame Alignment (LFA) condition, if the alarm associated with the respective condition is not disabled (see “Configure LTU and NTU Interfaces” on page 39).
•When CRC-4 mode is disabled, the Si bit is transparently transmitted (that is, unmodified from the HDSL input data stream).
•When CRC-4 mode is enabled, the Si bit is set to a new CRC-4 multiframe signal and checksum (according to G.706).
•The E-bits are nominally set to 1 and set to 0 for each error in the incoming CRC-4 sub-multiframe.
Match the CRC-4 mode at each interface to the actual type of data present at that node in the system. Otherwise CRC-4 data will not be transparently transmitted in CRC-4 disabled mode. Also, non-CRC-4 data generates an LFA alarm in CRC-4 enabled mode.
UTU-701 and ETU-751 List 1 | August 9, 2002 | 15 |