S/UNI-IMA-4 Telecom Standard Product Data Sheet
Released
The RDAT is not sensitive to the alignment of ICP cells within a group. There is no
performance degradation even if all of the ICP cells in a group have the same offset.
If the device is in Any-PHY mode or UTOPIA L2 Single Port mode, there is only a single FIFO
shared among all of the groups. The RDAT ensures that no more than 16 cells are stored in the
shared FIFO for a single group. If the S/UNI-IMA-4 is in UTOPIA L2 Multi-port mode, each
group has its own FIFO. Note that each group does not have a dedicated buffer of 16 cells; the
16 cell limit is used to prevent a small number of groups from monopolizing the shared FIFO
depth. The shared FIFO is 124 cells deep.
If the group FIFO is not emptied in a timely fashion, data is dropped; this is similar to the
procedure used by any other PHY level device. The IDCC service request FIFO will always be
serviced regardless of the state of the Group FIFO. For multi-port mode, if the respective Group
FIFO is full, the cell will be dropped. In Any-PHY mode and UTOPIA L2 Single Port mode, if
either the shared FIFO is full or there are already 16 cells for the current group in the FIFO, the
cell will be dropped.
Receive Statistics
The RDAT will maintain statistics on a per-link basis during link data processing, and on a per-
group basis during ATM data processing. These statistics may be accessed though the indirect
ECBI register interface, and are defined in section 11.8. For the link statistics, eight statistics
are provided. The OIF anomaly statistics may be incremented in addition to one and only one
of the other seven statistics, as shown in the flow diagram in Figure 22.
Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC-2020889, Issue 2
68
PMC [ PMC-SIERRA, INC ]
