DS3181/DS3182/DS3183/DS3184
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Figure 10-42. DS3 Multiframe Framer State Diagram
Sync
Load
Verify
Timeout
2 multiframe loaded
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If multiframe alignment OOF is disabled, an Out Of Frame (OOF) condition is declared when three or more out of
the last 16 consecutive sub-frame alignment bits (F-bits) have been errored, or a manual resynchronization is
requested. If multiframe alignment OOF is enabled, an OOF condition is declared when three or more out of the
last 16 consecutive F-bits have been errored, when an OOMF condition is declared, or when a manual
resynchronization is requested. If multiframe alignment OOF is disabled, an OOF condition is terminated when
none of the last 16 consecutive F-bits has been errored, or when the DS3 framer updates the data path frame
counters. If multiframe alignment OOF is enabled, an OOF condition is terminated when an OOMF condition is not
active and none of the last 16 consecutive F-bits has been errored, or when the DS3 framer updates the data path
frame counters. Multiframe alignment OOF is programmable (on or off).
A Severely Errored Frame (SEF) condition is declared when three or more out of the last 16 consecutive F-bits
have been errored, or when a manual resynchronization is requested. An SEF condition is terminated when an
OOF condition is absent.
A Loss Of Frame (LOF) condition is declared by the LOF integration counter when it has been active for a total of T
ms. The LOF integration counter is active (increments count) when an OOF condition is present, it is inactive (holds
count) when an OOF condition is absent, and it is reset when an OOF condition is absent for T continuous ms. T is
programmable (0, 1, 2, or 3). An LOF condition is terminated when an OOF condition is absent for T continuous
ms.
A Change Of Frame Alignment (COFA) is declared when the DS3 framer updates the data path frame counters
with a frame alignment that is different from the current data path DS3 frame alignment.
A Loss Of Signal (LOS) condition is declared when the B3ZS encoder is active, and it declares a LOS condition. A
LOS condition is terminated when the B3ZS encoder is inactive, or it terminates a LOS condition.
An Alarm Indication Signal (AIS) is a DS3 signal with valid F-bits and M-bits. The X-bits (X1 and X2) are set to one,
the P-bits (P1 and P2) are set to zero, all C-bits (CXY) are set to zero, and the payload bits are set to a 1010 pattern
starting with a one immediately after each DS3 overhead bit. An AIS signal is present when a DS3 frame is
received with valid F-bits and M-bits, both X-bits set to one, both P-bits set to zero, all C-bits set to zero, and all but
seven or fewer payload data bits matching the DS3 overhead aligned 1010 pattern. An AIS signal is absent when a
DS3 frame is received that does not meet the aforementioned criteria for an AIS signal being present. The AIS
integration counter declares an AIS condition when it has been active for a total of 10 to 17 DS3 frames. The AIS
integration counter is active (increments count) when an AIS signal is present, it is inactive (holds count) when an