PM7340 S/UNI-IMA-8
PRELIMINARY
INVERSE MULTIPLEXING OVER ATM
DATA SHEET
PMC-2001723
ISSUE 3
INVERSE MULTIPLEXING OVER ATM
Figure 10
- IFSM State Machine
Valid ICP at unexpected position (with cell by cell hunting)
Missing ICP Cell
Starting
State
α=
consecutive
invalid ICP cells
β=
consecutive
errored ICP cells
IMA SYNC
IMA HUNT
(frame by frame)
One invalid or
errored/missing
ICP cell
One valid
ICP cells
γ=
consecutive
valid ICP cells
Valid ICP at unexpected position
(with cell by cell hunting)
IMA PRESYNC
(frame by frame)
During group start-up, the fields in the ICP cells are validated by the RX IMA
Protocol Processor (RIPP) block and the validated information is used to
determine whether the ICP cells are valid or not. Validation by the RIPP checks
the group fields of the ICP cell to ensure that they match the rest of the group
and checks the LID to ensure that it is unique in the group. An ICP cell is invalid
if either the IMA OAM Label, the LID, the IMA_ID, M, IFSN or the offset is not the
same as the validated values. If the ICP cell cannot be validated by the RIPP (.i.e
the IMA_ID is different from the rest of the group or the LID is a duplicate), the
IFSM will remain in the starting state.
Once the ICP cells are validated by the RIPP, the IFSM will enter the IMA Hunt
state. In this state, each cell will be examined to see if it is a valid ICP cell. When
a single valid ICP cell has been received, the IFSM will enter the IMA Presync
state.
While in the Presync state, at each expected ICP location (determined by the ICP
offset and the IMA Frame Length), the cell will be examined (frame by frame).
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
58
PMC [ PMC-SIERRA, INC ]
