Data Sheet
June 2002
TMXF28155 Supermapper
155/51 Mbits/s SONET/SDH x28/x21 DS1/E1
495
Agere Systems Inc.
21 28-Channel Framer Block Functional Description
(continued)
21.6 Receive Framer Nonalignment Mode (DS1/E1)
In the nonalign framing modes, the receive frame aligner does not frame to the receive line data. Other than bipolar
violations, AIS, and AUXP monitoring, there is no processing of the receive line data. The entire receive line frame
is given unmodified to the system interface.
21.6.1 Loss of Frame Alignment Criteria
There are two criteria for declaring loss of frame: frame bit errors and CRC errors.
Frame Bit Errors.
1. T1: two frame bit errors out of 4 frame bits (F
T
and F
S
bits checked).
2. T1: two frame bit errors out of 5 frame bits (F
T
and F
S
bits checked).
3. T1: two frame bit errors out of 6 frame bits (F
T
and F
S
bits checked).
4. T1: three frame bit errors out of 12 frame bits—DDS only (F
T
, F
S
, and time slot 24 F bits).
5. T1: two frame bit errors out of 4 frame bits (only F
T
bits checked).
6. T1: two frame bit errors out of 5 frame bits (only F
T
bits checked).
7. T1: two frame bit errors out of 6 frame bits (only F
T
bits checked).
8. T1: four frame bit errors out of 12 frame bits—DDS only (F
T
, F
S,
and time slot 24 FAS pattern).
9. E1: three consecutive incorrect frame alignment signals.
10. E1: three consecutive incorrect frame alignment signals or three consecutive incorrect non-FAS frames as indi-
cated by bit 2 in time slot 0 in frames not containing the frame alignment signal.
11. E1: 3 consecutive incorrect FAS or non-FAS frames.
12. 2.048 Mbits/s CMI: 2 consecutive missing code rule violations (CRVs).
CRC Errors.
The use of CRC errors to declare loss of frame is optional. CRC errors are monitored in the performance monitor
block.
In DS1 mode, ESF, and J-ESF formats only, N or more CRC-6 errors in a 1 s interval results in loss of frame align-
ment. N is provisionable. N defaults to 320 in DS1 mode.
In CEPT mode, N or more CRC-4 errors in a 1 s interval results in loss of frame alignment. N is provisionable. N
defaults to 915 in CEPT modes.