S/UNI-IMA-4 Telecom Standard Product Data Sheet
Released
The completion of the command is generally indicated by an event that indicated either that the
process timed-out or the links have become operational. If a timeout occurs, PM should take
appropriate action and either restart the LASR procedure in the case that the handshaking was
just slow or replace defective links.
The event that indicates that the Start_LASR command has completed successfully for
symmetrical groups is the TX_ACTIVE_INT for all links involved. Due to the group-wide
synchronization, this event should occur for all links simultaneously. For asymmetrical groups,
the RX_ACTIVE_INT indicates the completion of the LASR for receive links.
Events that indicate that individual links are experiencing problems and did not become active
are the following:
DIFF_DELAY_INT
INVALID_ICP_INT
RX_TIMEOUT_INT
TX_TIMEOUT_INT
If a link is rejected with a DIFF_DELAY_INT, and the “rx_add_delay_en” is disabled in the
RIPP group configuration memory, then it may be possible to correct the problem and recover
the link. A “read_delay” command can be issued after the LASR is completed to determine the
differential delay profile for the group. If the new link appears to be above the
RX_DELAY_TOL, the RX_DELAY_TOL can be increased, or delay may be removed from the
group (as described in section 13.5.13), as long as this will not cause the current slowest link to
detect an LODS_UNDERRUN (i.e. resulting depth is less than
MIN_LOWER_GUARDBAND). If the new link appears to be below the
MIN_LOWER_GUARDBAND (or negative in delay), then delay may be added to the group
(as described in section 13.5.14), as long as this will not cause the current fastest link to detect
an LODS_OVERRUN (i.e. resulting depth is greater than RX_DELAY_TOL –
MIN_UPPER_GUARDBAND). Once these measures have been taken, a new LASR operation
may be initiated (link recovery), and this link should then be accepted into the group.
Note that if a link is rejected during link addition due to differential delay problems, the
DIFF_DELAY_INT will be issued, but the LODS_OVERRUN_INT and
LODS_UNDERRUN_INT will not be set, as these interrupts are only evaluated after successful
link addition.
If a timeout event occurs, another LASR procedure must be execute to continue attempting to
bring links to the active state.
Note that the LIF_INT is automatically masked by the device during a group-wide procedure
that includes this link, such as add_group, Restart_group, or Start_LASR (for link addition and
link recovery). Therefore, the LIF_INT may not be used to determine the success of the link
addition. Also, note that, once a link has been rejected, LIF is not reevaluated until another
LASR procedure is executed (attempts at IMA framing are halted once the LASR experiences
timeout).
Proprietary and Confidential to PMC-Sierra, Inc., and for its customers’ internal use.
Document No.: PMC-2020889, Issue 2
284
PMC [ PMC-SIERRA, INC ]
