S/UNI-IMA-4 Telecom Standard Product Data Sheet
Released
To account for this, the requested delay must be appropriately derated:
R = A * ((M-1)/M)
To summarize, the maximum requested delay is defined:
R = [Min(group_depths) – Min_lower_guardband] * ((M-1/M)
13.5.14 Adding Delay to a Group
In certain situations, such as when many changes of far end transmit TRL LID occur (due to
slight rate inaccuracies that accumulate when switching references), delay may need to be added
to a group (either in response to an LODS underrun condition or to prevent one from occurring).
This may also be desirable if a link is rejected from a LASR operation with a
DIFF_DELAY_INT (and rx_add_delay_en is disabled for the group). In order to add delay, the
adjust_delay command can be issued. A read_delay command may be issued to determine the
largest amount of delay in the group (associated with the link with the smallest transport delay).
The maximum amount of delay that may be added to the group without causing LODS on links
in the group is:
Actual delay (A) = RX_DELAY_TOL - Max(group depths) – Min_upper_guardband
The Min_upper_guardband is specified in register 0x208, and defaults to a value of 3. The
RX_DELAY_TOL is specified in the RIPP Group Configuration Table. Due to internal deration
of the scheduling rate associated with ICP cells, the device will derate the requested delay
specified (R) with the command:
A = R * (M/(M-1)), where M is the frame length (32, 64, 128, 256)
To account for this, the requested delay must be appropriately derated:
R = A * ((M-1)/M)
To summarize, the maximum requested delay is defined:
R = [RX_DELAY_TOL - Max(group depths) – Min_upper_guardband] * ((M-1/M)
13.5.15 IMA Events
All of IMA events are reported via a group-based structure. IMA events include link defects and
link and group state machine changes. Any enabled IMA event will cause a RIPP_INTR. All
IMA events may be enabled for reporting at the Group/link level as well as a globally. Both the
individual link/group enable as well as the global enable must be set to have an IMA event
cause an RIPP_INTR.
Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC-2020889, Issue 2
287
PMC [ PMC-SIERRA, INC ]
