ADC HiGain H2TU-C-231 Manual page 32

Provisioning
SF Number
Fractional T1 Mode (FT1) Option. Fractional T1 circuits can be used in feeder networks to provide frame
relay service. If such circuits are maintained by a DDS test group, then these circuits must respond to DDS/DS0
latching loopback commands, the only tool test groups have at their disposal. A latching loopback, once it has
been initiated by the correct sequence, remains locked or "latched" until the correct loopdown sequence has been
detected.
The FT1 option, when enabled, allows the H2TU-C to respond to DS0 latching loopback commands and,
therefore, support fractional T1 frame-relay applications. This is in addition to the standard full bandwidth T1
2-in-5 loopup and 3-in-5 loopdown SmartJack commands. FT1 supports both the full T1 commands of ENA and
the new DDS latching loopback commands, which must also be enabled. (For more information about latching
loopback commands, refer to BellCore TA-TSY-000077, Issue 3, April 1986.)
The FT1 option supports both the DDS NI and DDS DS0 Data Port (DP) latching loopback sequences listed in
Table 11.
Enable Sequence
1
2A
2B
3
4
5
6
Disable/Loopdown
The sequences in Table 11
loopback is activated after the detection of Sequence 6. Upon completion of the enable sequence, the Test Center
continues to transmit FEV bytes in multiples of 20 until FEV confirmation bytes are returned, or until about
2 seconds have elapsed. If the confirmation bytes are not received, a failed attempt is reported. Anticipate the
24
Table 10. SuperFrame Format
Terminal Framing Bit
1
2
3
4
5
6
7
8
9
10
11
12
Table 11. DDS NI and DS0 DP Latching Loopback Sequence
Minimum Number
Byte Name
of Bytes
35 Transition in Progress (TIP)
35 NI Loop Select Code (LSC)
35 DS0 DP Loop Select Code (LSC)
100 Loopback Enable Code (LBE)
35 All Ones
100 LBE
32 Far End Voice (FEV)
35 TIP
are sent in time slot 1. The S in the Network Code column is a "don't care" bit. The
September 28, 2001
Frame Bits
SuperFrame Signaling Bit
1
0
1
0
1
0
LTPH-TP-1034-01, Issue 1
0
0
1
1
1
0
Network Code
S 0 1 1 1 0 1 0
S 1 0 0 0 0 0 1
S 0 0 0 0 1 0 1
S 1 0 1 0 1 1 0
S 1 1 1 1 1 1 1
S 1 0 1 0 1 1 0
S 1 0 1 1 0 1 0
S 0 1 1 1 0 1 0
H2TU-C-231 List 4E