PM7346 S/UNI-QJET
DATASHEET
PMC-960835
ISSUE 6
SATURN QUAD USER NETWORK INTERFACE FOR J2, E3, T3
over 1 second intervals with the Performance Monitor (PMON). Note that the
framer is an off-line framer, indicating both OOF and COFA events. Even if an
OOF is indicated, the framer will continue indicating performance monitoring
information based on the previous frame alignment.
Three DS3 maintenance signals (a RED alarm condition, the alarm indication
signal, and the idle signal) are detected by the T3-FRMR. The maintenance
detection algorithm employs a simple integrator with a 1:1 slope that is based on
the occurrence of "valid" M-frame intervals. For the RED alarm, an M-frame is
said to be a "valid" interval if it contains a RED defect, defined as an occurrence
of an OOF or LOS event during that M-frame. For AIS and IDLE, an M-frame
interval is "valid" if it contains AIS or IDLE, defined as the occurrence of less than
15 discrepancies in the expected signal pattern (1010... for AIS, 1100... for IDLE)
while valid frame alignment is maintained. This discrepancy threshold ensures
-3
the detection algorithms operate in the presence of a 10 bit error rate. For AIS,
the expected pattern may be selected to be: the framed "1010" signal; the framed
arbitrary DS3 signal and the C-bits all zero; the framed "1010" signal and the C-
bits all zero; the framed all-ones signal (with overhead bits ignored); or the
unframed all-ones signal (with overhead bits equal to ones). Each "valid" M-
frame causes an associated integration counter to increment; "invalid" M-frames
cause a decrement. With the "slow" detection option, RED, AIS, or IDLE are
declared when the respective counter saturates at 127, which results in a
detection time of 13.5 ms. With the "fast" detection option, RED, AIS, or IDLE
are declared when the respective counter saturates at 21, which results in a
detection time of 2.23 ms (i.e., 1.5 times the maximum average reframe time).
RED, AIS, or IDLE are removed when the respective counter decrements to 0.
DS3 Loss of Frame detection is provided as recommended by ITU-T G.783 with
programmable integration periods of 1ms, 2ms, or 3ms. While integrating up to
assert LOF, the counter will integrate up when the framer asserts an Out of
Frame condition and integrates down when the framer de-asserts the Out of
Frame condition. Once an LOF is asserted, the framer must not assert OOF for
the entire integration period before LOF is de-asserted.
Valid X-bits are extracted by the T3-FRMR to provide indication of far end receive
failure (FERF). A FERF defect is detected if the extracted X-bits are equal and
are logic 0 (X1=X2=0); the defect is removed if the extracted X-bits are equal and
are logic 1 (X1=X2=1). If the X-bits are not equal, the FERF status remains in its
previous state. The extracted FERF status is buffered for 2 M-frames before
being reported within the DS3 FRMR Status register. This buffer ensures a
better than 99.99% chance of freezing the FERF status on a correct value during
the occurrence of an out of frame.
PMC-SIERRA, INC. PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA INC., AND ITS CUSTOMERS’ INTERNAL USE 57
PMC [ PMC-SIERRA, INC ]
