TMXF28155 Supermapper
155/51 Mbits/s SONET/SDH x28/x21 DS1/E1
Data Sheet
June 2002
448
Agere Systems Inc.
19 VT/TU Mapper Functional Description
(continued)
I
The incoming DS1/E1 signal will be checked for the AIS condition and reported in bit VT_TX_AIS[1—28]
(
Table 192 on page 163
). Any change in state of VT_TX_AIS[1—28] is reported in bit VT_TX_AIS_D[1—28]
(
Table 184
). Unless the VT_TX_AIS_M[1—28] (
Table 188 on page 162
) mask bit is set, VT_TX_AIS_D[1—28] =
1 will generate an interrupt.
I
If the incoming data is DS1, AIS will be declared if there are less than 9 zeros out of 8192 clock periods. If the
incoming data is E1, AIS will be declared if there are less than three zeros in each of two consecutive 512-bit
periods, and cleared when each of two consecutive 512-bit periods contains more than two zeros.
Transmit mapping modes are shown in
Table 570
.
Table 570. Transmit VT/TU Mapping Selection Per Channel, VT_TX_MAPTYPE[1—28][3:0]
19.14.2 Transmit Elastic Store (TES)
The TES logic block (in
Figure 40 on page 435
) will perform all functions necessary to synchronize the incoming
DS1/E1 or VT1.5/VT2 signals to the local STS-1/STS-3 clock.
I
This logic block will support the following modes of operation:
— Asynchronous, bit-synchronous, and byte-synchronous mapping from DS1/E1 input.
— Asynchronous, bit-synchronous, and byte-synchronous mapping from loopback VT1.5/VT2 input.
The TES logic block has programmable stuffing thresholds. The value programmed in the VT_HIGH_THRES[6:0]
(
Table 223 on page 174
) controls positive justification. The value programmed in the VT_LOW_THRES[6:0]
(
Table 223
) controls negative justification. The recommended values for nontributary loopback (VT_LB_SEL[1—
28] = 0 (
Table 211 on page 170
)) are VT_HIGH_THRES[6:0] = 0x28 and VT_LOW_THRES[6:0] = 0x27. Otherwise
(VT_LB_SEL[1—28] = 1), the recommended values are VT_HIGH_THRES[6:0] = 0x05 and VT_LOW_THRES[6:0]
= 0x04.
The TES logic block monitors for elastic store overflow conditions and reports with bit VT_TX_ESOVFL_E[1—28]
(
Table 184 on page 160
). Unless the VT_TX_ESOVFL_M[1—28] (
Table 188 on page 162
) mask bit is set,
VT_TX_ESOVFL_E[1—28] = 1 will generate an interrupt.
VT_TX_MAPTYPE[1—28][3:0]
(
See Table 211 on page 170
.)
0
0
0
0
1
1
0110—0111
0
0
0
1011—1111
Description
0
0
0
0
0
0
0
0
1
1
0
0
0
1
0
1
0
1
Asynchronous VT1.5/TU-11 (DS1 input).
Asynchronous VT2/TU-12 (E1 input).
Byte-Synchronous VT1.5/TU-11 (DS1 input).
Byte-Synchronous VT2/TU-12 (E1 input).
Bit-Synchronous VT1.5/TU-11 (DS1 input).
Bit-Synchronous VT2/TU-12 (E1 input).
Undefined, Generates VT1.5/TU-11 UNEQ-V.
Asynchronous VT2/TU-12 (DS1 input).
Byte-Synchronous VT2/TU-12 (DS1 input).
Bit-Synchronous VT2/TU-12 (DS1 input).
Undefined, Generates VT2/TU-12 UNEQ-V.
1
1
1
0
0
1
0
1
0