RELEASED
PM73123 AAL1GATOR-8
DATASHEET
PMC-2000097
ISSUE 2
8 LINK CES/DBCES AAL1 SAR
Figure 34 Fast SN Algorithm
invalid SN/discard
START
valid SN/discard (unless
NODROP_IN_START is set)
invalid
SN/discard
invalid
SN/discard,
force
invalid
SN/discard,
force
out of
seq/discard
underrun
underrun
OUT OF
SYNC
out of
seq/discard,
force underrun
out of
seq/discard,
force underrun
in seq/accept
out of seq/accept
in seq-1+1/accept
invalid SN/accept
OUT OF
SEQUENCE
in seq-1/discard
in seq/insert cells/accept
in seq-1/discard
SYNC
INVALID
in seq-1+1/accept
in seq/accept
All cells received while in the SYNC state are accepted whether or not they are
good. Any errored cells received while in the SYNC state are marked as
potentially bad cells. These marked cells will not have their pointers checked, or
bitmask checked, if they contain one; or if they contain signaling data, the
signaling data will not be written to memory.
If the cell is accepted, the RALP then transfers the cell to the external memory
using the R_CHAN_ALLOC fields in the R_QUEUE_TBL. Figure 35shows this
receive cell process. If a valid cell is not received in time, the queue may enter
an underrun condition.
Note that during an underrun, the RALP ‘Fast’ sequence number processing
state machine freezes in its current state. For example, if the state machine is in
the SYNC state when underrun occurs, when the next cell arrives, potentially
some time later, the state machine will still be in the SYNC state.
PMC-SIERRA, INC. PROPRIETARY AND CONFIDENTIAL
110
PMC [ PMC-SIERRA, INC ]
