
DS3141/DS3142/DS3143/DS3144 Single/Dual/Triple/Quad DS3/E3 Framers
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Table 7-E. DS3 Alarm Criteria
ALARM/
CONDITION
FUNCTION
SET CRITERIA
CLEAR CRITERIA
AIS
Alarm Indication Signal. Properly
framed 1010... pattern (starting
with 1 after each overhead bit),
all C bits set to 0
In each 84-bit information field, the
properly aligned 1010... pattern is
detected with fewer than four bit
errors (out of 84 possible) for 1024
consecutive information bit fields
(1.95ms) and all C bits are
majority decoded to be 0 during
this time.
In each 84-bit information field, the
properly aligned 1010... pattern is
detected with four or more bit errors
(out of 84 possible) for 1024
consecutive information bit fields
(1.95ms)
RUA1
Unframed All-Ones
Four or fewer 0s in two
consecutive 4760-bit frames
Five or more 0s in two consecutive
4760-bit frames
LOS
Loss of Signal
192 consecutive 0s
No EXZ events over a 192-bit
window that starts with the first 1
received
OOF
Out of Frame. Too many F bits or
M bits in error.
Three or more F bits in error out of
16 consecutive, or two or more M
bits in error out of four consecutive
No errors in six consecutive sets of
four F bits followed by two
consecutive frames with no M bits
errors, X bits matching and P bits
matching
SEF
Severely Errored Frame
Three or more F bits in error out of
16 consecutive F bits
In sync (OOF = 0) and fewer than
three F bits in error out of 16
consecutive F bits
RAI
Remote Alarm Indication (Also
referred to as SEF/AIS in
Bellcore GR-820.)
X1 = X2 = 0 (active)
X1 = X2 = 1 (inactive)
X1 = X2 = 0 for four consecutive
M-frames (426
ms)
X1 = X2 = 1 for four consecutive M-
frames (426
ms)
T3IDLE
DS3 Idle Signal. Properly framed
1100... pattern (starting with 11
after each overhead bit), the C
bits in M-subframe 3 set to 0
In each 84-bit information field, the
properly aligned 1100... pattern is
detected with fewer than four bit
errors (out of 84 possible) for 1024
consecutive information bit fields
(1.95ms), and the C bits in M-
subframe 3 are majority decoded
to be 0 during this time
In each 84-bit information field, the
properly aligned 1100... pattern is
detected with four or more bit errors
(out of 84 possible) for 1024
consecutive information bit fields
(1.95ms)
Table 7-F. E3 Alarm Criteria
ALARM/
CONDITION
FUNCTION
SET CRITERIA
CLEAR CRITERIA
AIS
Alarm Indication Signal.
Unframed all ones.
Four or fewer 0s in two
consecutive 1536-bit frames
Five or more 0s in two consecutive
1536-bit frames
RUA1
Unframed All Ones
Four or fewer 0s in two
consecutive 1536-bit frames
Five or more 0s in two consecutive
1536-bit frames
LOS
Loss of Signal
192 consecutive 0s
No EXZ events over a 192-bit
window that starts with the first 1
received
SEF
Severely Errored Frame
Same as OOF
OOF
Out of Frame. Too many FAS
errors.
Four consecutive bad FAS
Three consecutive good FAS
RAI
Remote Alarm Indication
Inactive: bit 11 of the frame = 0
Active: bit 11 of the frame = 1
Bit 11 = 1 for four consecutive
frames (6144 bits, 179
ms)
Bit 11 = 0 for four consecutive
frames (6144 bits, 179
ms)