
TMXF28155 Super Mapper
155/51 Mbits/s SONET/SDH x28/x21 DS1/E1
Preliminary Data Sheet, Rev. 1
October 2000
346
Lucent Technologies Inc.
M13/M23 Mux/Demux Block Functional Description
(continued)
M13/M23 Demultiplexer
(continued)
E1 Mode
Framer.
The M12 demultiplexers determine if the input signal contains a valid frame format as specified in ITU-T
Recommendation G.747. Frame alignment is declared (M13_DS2_OOFy = 0 (Table 241)) when a correct frame
alignment signal is received for three consecutive frames. The maximum average reframe time is 0.5 ms in the
presence of a bit error rate of 10
-3
. Out-of-frame is declared (M13_DS2_OOFy = 1) if the frame alignment signal
contains at least 1-bit error for 4 consecutive frames. For testing purposes, the user may also force the framer out-
of-frame by setting M13_DS2_FORCE_OOFy (Table 258) to 1.
Overhead Processing.
The C bits for each E1 channel are checked for loopback requests. If the third Cz bit differs
from the first and second Cz bits for 5 successive frames, M13_DS1_LB_DETx (Table 250) is set to 1, where x =
(4y – 4 + z). M13_DS1_LB_DETx is cleared when the third Cz bit does not differ from the first two Cz bits for 5 suc-
cessive frames.
If the RAI bit in 4 consecutive frames is received as 1, the M13 sets M13_DS2_RAI_DETy to 1 (Table 244). Once
M13_DS2_RAI_DETy is set, it is not cleared until the RAI bit is received as 0 in 4 consecutive frames. The received
reserved bit is reported through the M13_DS2_RSV_RCVy (Table 246), which is updated only when a new value is
received in 4 consecutive frames.
Loss of Frame and Automatic AIS Insertion.
The M13_DS2_LOFy (Table 242) bit is set when M13_DS2_OOFy
is high continuously for 28 DS3 frame periods (approximately 3 ms). Once set, M13_DS2_LOFy is not cleared until
M13_DS2_OOFy is continuously low for 28 DS3 frame periods.
The user can provision the M13 to automatically output AIS if either bit M13_DS2_OOFy = 1 (by setting
M13_AUTO_AIS_OOF to 1), or M13_DS2_LOFy = 1 (by setting M13_AUTO_AIS_LOF to 1).
DS2 Performance Monitors.
Within each M12 demultiplexer, there are 2 performance monitoring counters. These
counters are cleared and read as described above (see DS3 Performance Monitors on page 344).
Registers M13_DS2_FERR_CNT[7—1]_R (Table 295) count errors in the frame alignment signal. In the DS1
mode, M13_DS2_FERR_CNTy (Table 295) increments each time an error is detected in either an F bit or M bit. In
the E1 mode, this counter increments either for each frame alignment signal bit error (when
M13_DS2_FERR_MODE = 0 (Table 275)), or once for each frame alignment signal that contains at least one bit
error (when M13_DS2_FERR_MODE = 1).
In the E1 mode only, registers M13_DS2_PERR_CNT[7—1]_R[1—2] (Table 294) count errors in P bits.