S/UNI-IMA-4 Telecom Standard Product Data Sheet
Released
Word Bits
Parameter
Description
IMA mode: this field is indexed by the Physical Link tag and
is used to determine the cell count within a frame at which an
ICP is to be inserted for the link. The width of the field used
by the TIMA is dependent on the value of M used for the
particular group and is shown in the following:
23:16 ICP offset or TC mode
VPHY address
M=256 ICP offset determined by bits [23:16]
M=128 ICP offset determined by bits [23:17]
M=64 ICP offset determined by bits [23:18]
M=32 ICP offset determined by bits [23:19]
The mapping of the ICP offset is set such that the offset
should not have to be changed if M is changed. Values 0 to
255 are valid.
TC mode: this field is indexed by the TC tag delivered by the
IDCC and is used to determine the VPHY ATM source FIFO
associated with the TC connection. Only values 0 to 3 are
valid.
15:13
Reserved
12:9
Link FIFO Depth on
SOF
Count value used to store the link FIFO depth that existed
before the first cell was sent to the corresponding link FIFO
at the start of the most recent frame. Maintained but is not
used by internal TIMA logic. The data is still useful for
monitoring the link FIFO depths from the PM layer.
8:6
Startup Cell Count
Cell count used to track the first cells sent into each Link
FIFO after startup. Used to inhibit cell reads from the Link
FIFO until 7 cells have been written into the Link FIFO so
that the nominal cell depth can be achieved. This field must
be initialized to 7 by PM before the link is enabled to ensure
proper startup. However, if the link is to be used for a TC
mode connection, this field must be initialized to a value of 0
to prevent any read inhibit.
5:3
2:0
Reserved
Previous LSI
Link Stuff Indication. Decrementing count field used to count
ICP cells until a stuff event (if scheduled). Decremented and
then inserted into octet 10 of ICP cells associated with the
link. Used only in IMA mode and maintained by TIMA. Must
be initialized to 111b by PM before link startup.
IMA mode: this field is indexed by the Physical Link tag and
is used to store a continuously running count of the number
of Stuff Events inserted on the link. It is maintained by the
transmit engine and is read by the PM. This field should only
be reset when the link is not enabled.
1
31:16 IMA Mode Stuff Event
Count
or TC Mode User Cell
Count (upper word))
TC mode: this field is indexed by the TC tag delivered by the
IDCC and is used to store the upper 16-bit word of a
continuously running 32-bit count of the total number of ATM
user cells sent on the link. It is maintained by the transmit
engine and is read by the PM. This field should only be reset
when the link is not enabled.
Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC-2020889, Issue 2
244
PMC [ PMC-SIERRA, INC ]
