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Data Sheet
2-38
04.2000
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If the LB indication of an LB cell is equal to 1 and an LB location ID of the LB cell is equal to the
network element ID (LB location ID match) the LB indication flag is set to 0 and the LB cell is
looped back (loopback point, see
ILJXUH
, marker
ó
). This means that the AOPE ASIC sends
the LB cell to the opposite direction of AOPE (from upstream direction to downstream direction
and in opposite direction). In case of an LB location ID mismatch the LB cell is discarded.
Additionally the loopback processing sets a ’consistency’ flag for the μP only at the VP
terminating end point (AOPE upstream) in order to support the VPCI consistency check. The
’consistency’ flag is reset by SW.
If the LB indication of an LB cell is equal to 0 (LB cell already looped) and the connection is in
LB state (LB state = 1) and the source ID of the LB cell is equal the network element ID (LB
source ID match) the LB cell is dropped into the receive cell buffer of the μP (see
ILJXUH
marker
ì
). If the LB source ID flag of a connection is disabled or an LB source ID mismatch
occurs then the LB cell is discarded. If the connection isn’t in LB state (LB state = 0) the LB cell
is discarded.
,
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AOPE
AOPE
AOPE
LB status = 1
AOPE
LB status = 0
AOPE
LB status = 1
AOPE
insertion of F4 LB cell
drop LB cell to μP
receive cell buffer
configured as an
F5 orginating end point
configured as an
F4 originating end point and
F5 originating segment point
configured as an
F4 intermediate point
configured as an
F5 terminating end point
configured as an
F4 terminating end point and
F5 terminating segment point
configured as an
F4 intermediate point
configured as an
F4 terminating end point and
F5 intermediate point
configured as an
F4 originating end point and
F5 intermediate point
configured as an
F5 terminating segment and
F5 terminating end point
configured as an
F5 originating segment and
F5 originating end point
LB cell
looped back
configured as an
F4 intermediate point
configured as an
F4 intermediate point
set flag for VPCI
consistency check
3
1
2
VPCI consistency flag